Friday, December 31, 2010

Blog 11 -- Double Victims of life and reputation

I read Irene Nemerovsky’s Suite Francaise, an excellent book she never completed because she was in Auschwitz and died there of typhus (Nazi file) or the gas chamber (Holocaust file). In either case she was sent there because her family had converted to Catholicism and abandoned their Jewish identity. To the Nazis that was irrelevant. It was the parental Jewishness that stained her birth. Nor did it matter to the Nazis that she wrote occasionally for anti-Semitic publications although she was not a self-hating Jew. Reading Suite Francaise reveals nothing of her views on Jews. The Germans in her novel are occupiers. They are hated for occupying France and not much different than the people in the occupied villages. It is a story of the stupidity of war and the stupidity of those who get caught up in war, as conquerors or as conquered. It is also sympathetic to all its victims on both sides. She brings out the humanness that is often masked by our tendency to think in ideological terms of good and bad. Nemerovsky was killed not because her family tried to assimilate nor did they do anything offensive. She died because she was of Jewish ancestry and that was sufficient for the Final Solution. She is no less a victim of the Holocaust just because she accepted the Catholicism her parents imposed on her from birth. Nor does it make her a lesser victim because she turned her back on her Jewish origins and saw herself as a Catholic sharing their European views (including a tolerance of anti-Semitism) then current in the 1920s and 1930s.

Thursday, December 30, 2010


In January 2011 the journal GENETICS will carry a “Perspectives” article on my mentor, H. J. Muller. It was nice to be asked to write about him and it shows his legacy continues two generations after his death when most of his contemporaries in genetics have been forgotten. I wrote on the theme of the price a scientist pays for speaking out on issues concerning science and society. It can be costly; as it was in Muller’s case who went from country to country as politics changed and he became an unwanted critic. Gadflies are necessary but rarely admired while they are alive. Look at Socrates, perhaps the most well-known of social gadflies.

Wednesday, December 29, 2010

Blog 9 -- Serendipity and a scholar's browsing

I had to find a reference to an item I cited in an article. It was on Muller’s testimony to the House Un-American Activities Committee in March 1953. Muller was asked to testify about his stay in the USSR from 1932-1937 when he lost his enthusiasm for Communism and became embroiled in a debate with a movement that denounced genetics as bourgeois, racist, and false. I found the article using microfilm for the Indiana Daily Student, a campus newspaper that goes back to the 1860s. As I hunted for the issue, I looked at the ads and campus activities of the time. I was struck by their views of gender (males were doctors and females were nurses). There was also a Cold War expectation of nuclear attack. Stalin had just died so the future was uncertain. There was also one constant—the thrill of victories for a winning campus team and in those days IU was a national champion in basketball.

Tuesday, December 28, 2010

Blog 8 -- Feline memories and a new cat

Erica was given a cat by her daughter’s mother-in-law and brought it home on Christmas eve as she returned from a visit to Cincinnati. The cat is named Lilly and she is three years old. She was terrified by the ride home in a pet cage and equally scared by her new home. This morning we spent two hours looking for her and finally found her under a shelf in a closet in my study. She is a tabby. I’ve only known cats and not dogs as pets. They are easier to manage in apartments and I grew up in apartments in NYC. She reminded me of our cats past—Buddy, Kittikins, DeBoogie, and Minneloushe.

Monday, December 27, 2010

Blog 7 --Indiana starts American eugenics in 1907

I got a book in the mail from IU Press. I had contributed a chapter in a book edited by Paul Lombardo. A Century of Eugenics in America. It was based on a conference I had attended about two or three years ago. I was asked to discuss the Indiana origins of the compulsory sterilization laws that Indiana initiated in 1907. I thought about how easily we are convinced that other people are inferior to us. What is pernicious is not the people but the outlooks they offer. We are not born communist or fascist, liberal or conservative. It is not in our genes to hate Jews, blacks, gays, Catholics, or WASPs. All of that is learned. So too are our attitudes about the rich and the poor, laborers and elites. Changing views is not easy for those reared in prejudice or privilege, poverty of wealth. The religions in which we are raised are often life-lasting. Tolerance, respect, and appreciation for diversity are also learned. Yet it is so easy to see behavior in others as “bred in the bone” if not engraved in our DNA sequences.

Sunday, December 26, 2010

Blog 6 -- Reflections on getting a haircut

I am one of those individuals, like my father, who has kept a full head of hair as an adult. About 60 percent of men lose a good portion of their hair after they turn 20 and by middle age they show pattern baldness because they carry that particular gene. Each time I get a haircut I look at the snippets of hair as they fall and I note how the white hairs now swamp out the chestnut hairs of my youth. But I also celebrate that capacity of follicle cells to manufacture the mixture of keratin and dead cells that make up each shaft of hair. It tells me I am alive and kicking in my old age. I do not know why our hair continues to grow faithfully regardless of age, but when I look at my wrinkled skin and wince at my arthritic joints, I realize there must be something special about those follicle cells and I wish their trick of chugging out hair was shared with my other tissues.

Saturday, December 25, 2010

Life Lines 100 -- PCR and Crime

About twenty years ago Kary Mullis discovered a technique to clone small amounts of DNA. He called this process polymerase chain reaction or PCR. DNA is our genetic material and indeed the hereditary stuff of all cellular life. The technique uses heat to separate the two strands of DNA and some fancy regions are attached, which allows primers that recognize them to begin copying the separated strands. The process takes a few hours to generate a million-fold increase in DNA of any given type.

The PCR technique is very useful for geneticists who wanted to study the isolated genes or fragments bearing genes from any organism. They can use the technique to study the DNA of long dead organisms from humans ancestors to extinct quaggas and dodos. But most striking has been the application of PCR studies to crime.

DNA is found in cells. We are composed of tens of trillions of cells. Every time we lick a stamp or envelope we leave some cells with our saliva on the paper and glue. When we drink from a glass, toss a tissue that we used to wipe our nose or mouth, we discard some of our cells. Dandruff flakes, hair, the aerosol of our sneeze can also scatter our DNA about. The man who rapes his victim leaves tell tale evidence on clothing. A criminal’s DNA will be found under the nails of a victim who scratches her assailant. Any cut by a criminal will leave drops of blood as evidence.

The first few years that PCR evidence was used to convict criminals, it was vigorously challenged by defense attorneys, just as early attempts to use fingerprints were resisted until the public and the courts got used to the accuracy of the methods used to establish identity. To the surprise, and disappointment, of district attorneys, the PCR evidence works both ways. Many convicted rapists were released because the crime, and not the criminal was convicted. Shady looking people at the wrong place and time are sometimes railroaded into prison and PCR has been their deliverance. Both the prosecution and the defense benefit from this reversal of fortunes because if the technique is valid the DNA evidence can be very convincing.

Why then did the jury reject the PCR evidence in the Simpson case? Some believe in conspiratorial theories – that Simpson was framed and his blood dribbled here and there by racist enemies. Some still discount the evidence because it is relatively new compared to fingerprints. There is another reason too. Juries consider what is right and wrong differently from professionals who know, teach, and practice the law. I remember, years ago, when Charlie Chaplin was very unpopular for his communist sympathies. He had an alleged affair of many months duration with a “crumpet girl,” whom he had befriended. She became pregnant. She sued for child support. A test for blood groups (the method then in use in some 40 years ago) revealed Chaplin was not the father. He was convicted. Why would a jury convict a person whose sperm did not produce this child? I remember reading a comment of one of the jurors: Chaplin cohabited with her; he could have been the father; he can afford it; it was only luck that someone else was also intimate. Sometimes a moral view prevails over a technical one.

Life Lines 99 -- Intellectual Pedigrees

A pedigree shows the members of a kindred. The kindred consists of one’s immediate family and other relatives, including uncles and aunts, cousins, great uncles and great aunts. Those who do genealogy know how fast such pedigrees can grow. In human genetics they are useful for identifying relatives at risk for inherited disorders and genetic counselors frequently take such extended family histories when figuring out the passage of genes to an affected child. I have frequently prepared such pedigrees for students when they ask me about a genetic condition running in their families. The geneticist uses circles to represent females and squares to represent males. They are connected by horizontal and vertical lines to show their relationship to one another.

Scholars sometimes construct a different kind of pedigree. They like to show how they are connected to other scholars. This is almost as much fun as learning who one’s ancestors were. For example, I got my PhD at Indiana University with Nobelist H. J. Muller who first induced mutations with x-rays in 1927. He got his PhD with T. H. Morgan who got his Nobel Prize in 1933 for working out the principles of classical genetics with fruit flies, chiefly for his work on what is called X-linked inheritance (traits such as color blindness, hemophilia, and Duchenne muscular dystrophy) and crossing over (the shuffling of genes between related chromosomes). Morgan was at Columbia University when this work was done by his laboratory. Morgan got his PhD with William Keith Brooks and H. Newell Martin at Johns Hopkins University, the first modern graduate research program in the United States. Brooks was a zoologist who studied oysters and other invertebrates. Martin was from England, recruited because he was an experimental physiologist. Brooks got his PhD from Alexander Agassiz at Harvard. Agassiz was a founder of Woods Hole, the first experimental biology station in the US. Martin got his advanced training from Thomas Henry Huxley, an evolutionist who was influenced by Charles Darwin and who championed his work for him. He was so effective speaking in public on behalf of Darwin’s views on evolution that he is known as “Darwin’s Bulldog.” Alexander Agassiz got his graduate education from his father, Louis Agassiz, one of America’s most famous nineteenth century scientists who came to the US from Switzerland. He was the Carl Sagan of his day and did much to popularize science in America.

In a genetic pedigree there is a reduction by 50% of the amount of heredity one gets from each ancestor as one moves back one generation. Thus my great-great grandfather, Carl Frederick Pettersson, contributed about 7% of my genes. There is no way to assess the influence of ideas in one’s intellectual pedigree. Most of the intellectual heirs of Darwin shared an enthusiasm for evolution by natural selection. But none of the intellectual heirs of Louis Agassiz shared his views on the Divine Creation of life. Agassiz, true intellect that he was, respected his own students who all became strong supporters of Darwin’s theory of evolution by natural selection. While heredity distributes its genes across the generations in predictable ways, ideas are far more uncertain. Some ideas are shared indefinitely after they are established and others may be short-lived.

Life Lines 98 -- What are protease inhibitors?

We hear about AIDS patients taking multiple medications to prevent their infected white blood cells from making new HIV particles. One of those agents directly damages virus DNA; it can, alas, also damage human DNA. The other major agent is called a protease inhibitor. Proteases are proteins that act as enzymes to cleave certain proteins the virus makes.
The HIV chromosome has several genes. When the virus enters a white blood cell, it converts its RNA chromosome into a DNA chromosome. The DNA chromosome then enters the cell nucleus and inserts itself. Occasionally, some of its genes are decoded back to RNA. At one end of the virus chromosome, two such regions are copied as a single thread and they are in turn decoded into a long protein. That long protein is chopped into six smaller pieces by an enzyme from another part of the virus chromosome. That enzyme is a protease.
If there is no protease in the cell, then defective viruses are put together and they can’t infect cells. A protease inhibitor prevents protease from cutting up the virus proteins into its needed pieces. It does not kill already infected cells.
Protease inhibitors are very effective and they can prevent viruses from being made as long as the body is supplied with protease inhibitors. If the person stops using protease inhibitors, then the virus chromosomes that were inserted into the white blood cells will resume making viruses.
The optimistic hope is that the body will have enough time to rebuild its immune system and take care of such new viruses if protease inhibitors are no longer given. The pessimistic expectation is that the virus would ultimately come back strong and to prevent it, protease inhibitors must be given for life. So far, neither view is a clear winner. It costs about $4,000 to $6,000 per year to supply one patient with protease inhibitors. There are four different protease inhibitors that have been synthesized and approved for medical prescription. The cost is high because the inhibitors are complex molecules that are difficult to manufacture. Add to that the tens of millions of dollars spent to prove that the drug will not make the patient sicker and to prove that it really does what it claims it does, and you can readily see how some drugs are worth their weight in rare postage stamps.
Now that protease inhibitors have been used for several years, AIDS patients who thought they would be dead in a year are suddenly finding that they can work again and are making plans for the coming years. They are also discovering some long-term side effects, including a curious deposit of fat around the viscera making their abdomens bulge.
The fight to eliminate AIDS will be a long one. There are over 30 million cases worldwide and for the near future we will see several tens of thousands of new cases in the United States. Many countries are still not taking measures to prevent the spread of AIDS, many of them hoping a vaccine will be found to solve the problem. There are many such vaccines in the works but each has its own uncertainty about how well it will work. Any virus that makes the immune system its meal ticket has a lot of skills getting through those defenses.

Life Lines 97 -- Saboteurs of the Cell

It is not easy to think very small. We like to think of small as something about the size of a dust mote, a speck barely visible to our eye. That’s big compared to almost any cell of our body. Thousands of cells can fit on the head of a pin. Without a microscope those cells would be invisible to our eyes. Yet a single cell is immense compared to a virus. Most viruses cannot be seen by microscopes that readily reveal bacteria. Viruses are organisms that are hundreds to millions of times smaller than any of our cells.

We know of viruses as germs, and we lump all organisms that cause disease under that term. Until the 1940s it wasn’t clear what viruses were. Some did not think they were organisms. Some thought they pre-exist in cells and are just jarred loose from their slumber inside the cell. A few could not distinguish between viruses and genes. Several things changed our views about viruses and much of that work was worked out more than 70 years ago on Long Island at Cold Spring Harbor. Max Delbruck, who left Nazi Germany to study genetics began using bacterial viruses in 1938 at Cal Tech. He got together with other scientists at Cold Spring Harbor and worked out some of the first experiments to show that bacterial viruses were more complicated than genes, that they had a life cycle, and that the bacteria on which they fed underwent mutations making them resistant to infection. A new instrument, installed at Cold Spring Harbor, the electron microscope, revealed the viruses as lollipop-shaped organisms that attached to bacterial walls by their stems.

Most bacterial viruses are big as viruses go. They contain 100 or more genes. Most of the genes that make us sick are much smaller such as those causing polio, flu, measles, or mumps. On average they contain about 10 to 15 genes. Human immunodeficiency virus, which causes AIDS, is also small but it is more complex in structure and function. Viruses can be crystallized because they are just molecules of nucleic acid and protein. They have no metabolism of their own and they subvert the cell by taking over its metabolism. They are like smuggled tapes inserted into a tape recorder.

We know the story of small David slaying the giant Goliath. A virus is much more tiny than the cell it infects. As the infected cell releases hundreds of new viruses, the viruses spread and in a day’s infection staggering quantities of virus can be produced. If they overwhelm the immune system, the virus infection can kill. This happens with such terrifying diseases as yellow fever or small pox. The 1919 variety of flu was another killer, turning young adults overnight from health to drowning corpses, the lung’s air sacs bursting and filling up with blood. Fortunately most viruses are not that lethal.

It is difficult to kill viruses once they are in the cell. Most of the things that damage the viral genes also damage human genes; most of the substances that damage the virus proteins also damage human proteins. This is why most virus diseases are prevented by vaccinations. It took many years to make safe vaccines against polio. It should not surprise us that the prevention of AIDS by vaccine may still be several years away.

Lifelines 96 -- Linus Pauling

Linus Pauling was a chemist who lived a long and productive life. He received two Nobel Prizes, one for his work on the chemical bond and one for his efforts to get the US and the USSR to negotiate a ban on testing nuclear weapons in the air and sea. He could have won a third Nobel Prize had he not won the other two. He was the first to recognize and name a molecular disease. He demonstrated that sickle cell anemia, a disorder that afflicts some children of African American ancestry, was caused by a defect so small that it only altered one three hundredth of the hemoglobin molecule. He would have won a Nobel Prize for the third time if he had not made an error in interpreting the structure of DNA.

I met Pauling twice. The first time was at UCLA where I served as his host while he spoke on five different topics in as many days. He was politically controversial because of his efforts to get scientists to sign his petitions against testing atomic bombs in the atmosphere. None of the senior faculty in my department would host him to dinner so I volunteered and he and his wife had a dinner at my home and he met mostly a few graduate students and younger faculty like myself. I asked him about his error and whether he would have interpreted the DNA molecule correctly if he had seen Rosalind Franklin’s or Wilkins’s xray diffraction pictures which Watson and Crick used. He said science doesn’t work that way. You can sometimes see the obvious and not recognize it because of your expectations. I admired him for that honesty. Many competitors of Watson and Crick claimed that they would have seen the obvious if they had access to those photographs of DNA.

I met Pauling and his wife again at Stony Brook in 1969. I was the faculty advisor for Sanger College, a dormitory on our campus. The dormitory had funds for a dedication of the building. Pauling was scheduled to visit for a conference on crystallography. I told the students to write to Pauling and he graciously agreed to give a keynote talk (along with Margaret Sanger’s son).

In his later years Pauling became more controversial not because of his anti-war views but because he believed huge doses of vitamin C would prevent colds (and other diseases). His evidence was indirect and many people lost faith in his abilities as a scientist. Research with human subjects is much more difficult and less convincing than experiments that can be tightly controlled using bacteria, fruit flies, maize, or mice. Unfortunately these forms of life don’t get colds!

Pauling responded to claims that as a scientist he should not get involved in public controversies about cold war politics and radiation damage to our health because he was not an expert. Pauling said that if his critics read as much chemistry as he read articles and books on controversial issues, he would consider their advice. At least President Kennedy recognized what our Constitution and country is all about. He had dinner with Pauling the evening of the same day that Pauling picketed the White House.

Life Lines 94 -- Ignatz Semmelweiss and Childbed Fever

Ignatz Semmelweiss was a Hungarian born physician who went to Vienna for his advanced medical training. The Vienna General Hospital was a model of the modern mid-nineteenth century hospital. It stressed research and a scholarly approach to finding the causes of illness. The hospital had two large wards for obstetrics. One was for the poor and it was managed by midwives. The women ranged from working married poor to unmarried unfortunate young women cast out into the streets. The rooms were simple and clean but relatively austere as one would imagine for a public clinic. The other ward was for the middle class women who could afford a physician to attend them when they became pregnant. About 1840 a new chief of obstetrics came in. He wanted his medical students to do autopsies on every death to see what caused those losses. He wanted his medical students to train, under supervision, with female patients, not with the then much used leather models that had been the standard.

When Semmelweiss arrived there was a good deal of confusion. The death rates for women in the middle class ward were considerably higher than in the ward for the poor. This was the reverse of expectation because otherwise the poor were dying more often than the well to do. The pregnant women died of childbed fever after delivery. Their bodies would fill with a milky fluid and they entered into a delirium and coma as their bodies became overwhelmed. Semmelweiss plunged in and studied temperature, fresh versus stagnant air, cleanliness of bedclothes, even the color of the rooms. Nothing he examined was of help. After a few years he was on vacation and he got word that a senior physician who was his mentor had died.

He returned to Vienna and read the autopsy report. His friend had cut his finger and the description of his tissues were identical to those for childbed fever. Semmelweiss rejected the prevailing view that misplaced milk was the cause. Instead he imagined “putrid particles” had entered and killed his friend just as they had entered the bodies of the dozens of women who died each month. He tried cleaning his hands after autopsy with soap and water but the fingers still smelled of cadaver. He tried chloride of lime (very much like Clorox) after a soap and water scrubbing that was very thorough. That worked. He forced his medical students to wash their hands as he did and carefully supervised them. The rates fell and he had found a way to prevent childbed fever. It would be another twenty five years before the germ theory would be introduced.

The revolutions of 1848 got Semmelweiss into political trouble and he fought with his supervisor who considered his theory insulting and metaphysical. Semmelweiss wrote only a few notes and didn’t push his ideas. He was fired and went back to Budapest. He became abusive at home and his wife and brother-in-law conspired to get him back to Vienna on a ruse where he was brought to an asylum. He tried to escape when he saw he was being betrayed and he was severely beaten. He died a few weeks later, of childbed fever. Semmelweiss joins that small body of heroes, despised in their own time and revered with monuments generations later.



I have always admired the legend of Prometheus, who could see into the future and who shared his knowledge of science with humanity, a crime for which Zeus punished him.
Scientists are often promethean in their rash attempts to look into the future by seeing applications of their discoveries, and they are sometimes punished by their societies for saying things many do not wish to hear. Herman Muller and Linus Pauling, scientists I knew and admired, were like that. I cannot predict the future, of course, because I am not Prometheus. But, I can see some trends and problems that reflection about my science of genetics brings to my mind. I’ll share those with you.
The 21st century will be the century of the human genome project. With all 25,000 of our genes sequenced and their functions worked out, medicine will see new specialties arising especially for the treatment and prevention of genetic disorders. My prediction is that there will be more prevention than treatment because, for many disorders, the task of treatment would be like undoing scrambled eggs. But, prevention is controversial because it involves prenatal diagnosis and elective abortion. Right now, most of that controversy surrounds unwanted pregnancies for social reasons.
In the 21st century, the issue will shift because there will be far better means of family planning and birth control and thus, fewer social abortions and more based on medical conditions of the embryo. It also means there will be fewer surprises for couples intending to have children. Hundreds, if not thousands, of genetic disorders will be cheaply screened with technologies that are now at the planning stages using DNA microchips designed for different ethnic groups and the most common birth defects. The nature of elective abortion will also change as cases will be prenatally diagnosed during the first month of pregnancy, in many cases, by a blood test of the pregnant woman instead of by amniocentesis.
Two trends will be working in opposite directions. There will be a considerable reduction of disorders involving dominant mutations such as Huntington disease, achondroplastic, retinoblastoma, and Marfan syndrome because adults with these conditions will most likely use embryo screening by maternal blood test. This means the incidence of dominant mutations will plunge to their spontaneous mutation rates which is very low. For recessive disorders it is screened adults who will be making decisions about their children and I expect most of them will elect a healthy child who does not have that disorder. This will not diminish the incidence of the gene in the population because most of those infants, if born, will not live to reproductive maturity or have offspring. If curative methods are somehow developed, this will create long term problems because the genes that cause the problem are not altered by a satisfactory treatment for the symptoms of a disease. Those mutant genes will increase in the population each generation. At present we may have limited promethean foresight but no one can predict with confidence the long term values and behavior of our descendants centuries or millennia from now.

Life Lines 93 -- A Gene for Maleness

No one gene, of course, determines something as complex as sex. There are genes for our external and internal genitalia, our gonads (testes and ovaries) and for a variety of other attributes we identify with our differences in gender. When the human genome project is completed in less than a decade, I would not be surprised to find more than a thousand such genes among our 75,000 genes. There is, however, one gene that starts the early embryo in one direction or the other. This gene, discovered several years ago, is called SRY, an abbreviation for the sex-determining region of the Y chromosome. All normal males and females have two sex chromosomes in addition to 44 other chromosomes in each of their body cells.. Normal males have an X and a Y; normal females have two X chromosomes. The Y has very few genes. It is about one tenth the size of the X. One of these genes is the SRY. When it is present at fertilization, the developing embryo will become a male. It does so through the product of the SRY gene which converts the neutral gonads in the embryo into testes. Once testes form, the direction is inexorable and the normal XY embryo produces what one expects to find in a normal male. The absence of SRY (as in normal XX females) leads to female development.

The SRY gene has been isolated and sequenced which means that its structure is known as a sequence of nucleotides. In mice, when XX fertilized eggs are injected with the SRY gene, the newborn mice are anatomically and behaviorally male. They are sterile because other genes needed for making sperm are missing. In the human Y chromosome, a cluster of such genes associated with making sperm have also been identified. That region is called DAZ, an abbreviation for deleted in azoospermia. The term arose because a small portion of males who are sterile and produce no spermatozoa lack a region of their Y chromosome. Those genes are in the process of being sequenced.

Occasionally a small piece of the X and Y chromosomes get swapped when sperm are being made. This happens only about once in 50,000 sperm produced. This can lead to XX males or XY females. Usually XX males are normal except for the lack of spermatozoa. They contain the SRY gene which can be detected by a chemical analysis of the X chromosomes. Since they lack the genes of the DAZ region they make no sperm. Similarly XY females are usually females at birth and they are normal girls until they reach puberty when they fail to mature into women. They require hormone therapy to achieve their puberty and femininity but since they lack ovaries they are sterile. With in vitro fertilization, however, they can be surrogate mothers using a relative’s eggs or a donor’s eggs. XY females lack the SRY gene and thus their gonads were shifted to ovaries. These ovaries fail to mature because they only have one X and they need two X chromosomes to make working ovaries.

One of the pleasures of studying science is how powerful it is to explain what seems impossible or a contradiction to common sense. We expect males to be XY and females to be XX. When XX males and XY females were first encountered, this was a shock. As the tools of biochemistry became more sophisticated, the mechanisms producing these altered chromosomes were worked out. As biologists learn how genes make embryos, the understanding of how our body is put together becomes clear. It is a breathtaking picture that is emerging and the young scientists of the first decades of the twenty-first century will startle us with their findings.

Life Lines 92 -- Color Blindness

The correct designation today is impaired color vision because almost all persons with this genetic defect see some color, especially blues and yellows. About 6 to 8 percent of American males are red-green color deficient. They confuse these colors with each other or with grays. I remember demonstrating this in one class when I drew with red on a slate blackboard and one of my teaching assistants who had red-green color deficiency could not see what I had written

Color deficiency was first considered a hereditary defect by the founder of atomic theory, John Dalton in 1794. He had his eyes preserved after his death and a few years ago they were analyzed, the genes removed and cloned, and the mutation that caused his deficiency was similar to the one that effects many hundreds of thousands of people of Celtic ancestry today. For reasons not known, Celtic people have much higher frequencies of color deficiency (up to 20 percent of the males in some Irish villages). It is inherited from one’s normal visioned mother. Half of her sons are at risk and the father is normal. That is because the gene is on the X chromosome. The mother is usually a carrier (heterozygous is the fancy term). The father supplies a Y chromosome to his son and not an X. The Y has very few genes on it and thus sons are vulnerable to what’s on the X they got from their mother.

There are four major forms of red-greed color deficiency. The most extreme are protanopes and deuteranopes. Those are your classic cases of the guys who need a friend or a relative to help pick out their clothes. The former messes up the reds and the latter messes up the greens. A milder form of each results in protanomaly and deuteranomaly. Both the protan and deutan genes have been sequenced for their DNA. These genes deposit pigments in the cone cells of the retina. The rest of the retinal cells, rod cells, give us our night vision of white, grays, and black.

I once checked out a family with a color blind father and a carrier mother and they had a colorblind daughter and a color blind son among their growing family. It’s easy to do with Ishihara plates which are numbers made of colored dots against a sea of colored dots. My favorite moment is giving a normal person an Ishihara chart that shows a number only red-green color deficient people see. The usual response: “You mean there really is a number there?”

One of my students, Shari Cohn, studied female carriers and showed that under reduced lighting conditions such females, tested one eye at a time, make mistakes more frequently than women who do not have color deficiency in the family. This is because all females are a mixture of cells, about half expressing their father’s X and the other half expressing their mother’s X. They are natural mosaics. The movement of their eyes and the splitting of signals from each eye into the two hemispheres of the brain permits such women carriers to see normal color. I called my son to see whether my grandson got the gene from his other grandfather (who was colorblind) through his mother. My grandson couldn’t read numbers then but he knew his colors.

LIFE LINES 91 -- What is Reality?


Scientists usually ignore philosophers of science just as some artists ignore art critics or authors ignore literary critics. There is a gulf between those who interpret how a profession goes about its business and those who do their “sullen craft.” There are different philosophies of science. One of the oldest and hence one of the earliest to be repudiated, is Francis Bacon’s belief that scientists see patterns or ideas or laws of nature by immersing themselves in a lots of data. This is called induction. Many philosophers believe this is deceptive and claim most scientists really have their ideas before they get data to test or prove them. Two exemplars of Baconian science are Charles Darwin and Gregor Mendel. Darwin spent eight years of hard work before the idea of natural selection as a mechanism of evolution came to him from a mountain of data. Mendel spent seven years in his monastery garden before he figured out what we now call Mendel’s laws of heredity.

Some of my colleagues, especially in the social sciences, reject not only Baconian induction but the very heart of scientific belief – that we as scientists describe a reality that is out there. They think this is quaint and look for the day when the scales fall off our eyes and we will admit that reality is constructed. One of my colleagues tried to convince me that Darwin’s theory of evolution is just capitalism of the industrial revolution disguised as science. Another colleague in psychology claimed that all of science is just a way each generation constructs reality. He was not persuaded by his own argument, however, when one of his students, who got an F on the final, tried to show that the F was just a construction by his instructor and not an earned grade.

Artists construct a reality of their imaginations. And they are very enjoyable visions. If there is no underlying reality, how then does science differ from art? To the scientist it is the external reality that checks every scientific hypothesis and theory, constantly correcting it because our imaginations cannot fully anticipate nature. If there were no external reality to test our ideas or constructions, quack medicines should be as effective as those tested by carefully controlled experiments. Instead of penicillin we would be drinking concoctions made with turtle dung.

Social scientists are probably correct when they claim our knowledge of society is largely a construction because only bits of history, culture, and the remnants of civilization may be left behind for us to reconstruct. The New York City of 1875 may be very different from what we interpret it to be because many voices, events, preferences, habits and beliefs of the day may be lost. Psychologists are also correct that we are influenced in how we see things and interpret them. Few scientists would dispute this, but we know how often our own pet ideas fail to meet the test of observation or experimentation. Scientists rely on careful experimentation and verification by independent laboratories as their safeguard against self-deception. Consensus and authority are frequently spurned by scientists who much prefer the frustration of failed experiments, unexpected results, and inconsistency as a spur to discovery.

Blog 5 -- The Pleasures of Writing


I did not know I would be a prolific writer when I was in high school, but I did know that I loved to write. Sometimes, when given an assignment, I would write two essays instead of one because another idea would pop into my head. I would submit both, not because I was trying to please my teacher but because I was so pleased with the two different ways I handled a topic. Since I am a biologist I attribute the pleasure of writing to the endorphins I produce which create a sense of self-validation, of accomplishment, and a zest for life. I have had euphoria from a good drink, a pleasurable dinner, and many other pleasures of the flesh and senses but writing, scholarship, and learning have been the most satisfying of those experiences.

Monday, December 20, 2010


Next weekend I will close out the year 2010 by posting Lifelines 91-100. I have 200 more but will hold off putting them on line for about six months and then I’ll remove this first batch of 100 and post ten a week of the second 100. In the meantime I will resume this blog feature with shorter thoughts about science and its relation to society and our lives. We are ambivalent about the geek in some of us (including me) that likes to immerse ourselves with gusto into a subject. We applaud the Mozart, the Picasso, or the Dickens that can pour out one work after another without let-up sometimes frustrating others in those fields. We also applaud such talent among performers in the arts, actors, billionaires who earned their wealth, and sports legends. We are less charitable to those who are immensely productive but who are not household names. They are your scientists, journalists, poets, composers, clinicians, and teachers who are not household names. But without their energy and commitment to their fields we would be the poorer as a civilization and as individuals because it is their daily work that we often depend on.

Friday, December 17, 2010

Life Lines 90


Each generation has its own music, art, literature, and other ways of seeing and interpreting the universe. We seek nevertheless universal truths that are fixed and that will serve us a guide through life. For most of humanity it is found in a religion, one of several hundred contradictory religions, some believing in the existence one god, some in many gods, and some in no gods. The difficulty with these religious guidelines is their ease of reinterpretation. Each generation is selective in what it considers important to its own values. “Thou shalt not kill” has a myriad of exceptions for those who justify capital punishment, collateral deaths in bombings, or the vaporization of non-combatant men, women and children in Hiroshima and Nagasaki. In the past the justified killings included counterfeiting, blasphemy, atheism, pick pocketing, mutiny, and heresies of innumerable kinds. Falling asleep while on sentry duty was punishable by death.

It is not just commandments that we violate and justify; we reinterpret everything, all the time, because each generation has a different universe to live in. Old values are stretched to accommodate new priorities. In the 1940s I listened to radioevangelists condemning the sin of Mammon worship (materialistic wealth). Today televangelists praise the acquisition of wealth and no longer ask their wealthy donors to struggle about squeezing through a needle’s eye. We don’t condemn keeping up with the Joneses; we convince ourselves that we want the best for our children or our families.

Science also reinterprets the past. It does so with a different motivation in mind. It seeks to understand the physical universe of atoms and their activities from the subatomic to the galaxies of the universe including life on earth. Since modern science began with Galileo’s use of the telescope to examine the sun, moon, and planets we have had an unending series of understandings of how the physical laws of the universe work, how molecules are formed from atoms, how heredity works, how infectious diseases arise from germs, and how a fertilized egg eventually becomes an adult being. The applications of science necessarily involve values; and science is often abused by making weapons of mass destruction, by pollution from its by-products, and by inadequate regulation. Here the failings of applied science are no different from the failings of humanity more familiar to the past – bribery, influence peddling, nepotism, cronyism, greed, theft, and betrayal. Whoever harms another person, intentionally or not, justifies that behavior as being done for a higher cause. That higher cause can be religion, patriotism, one’s family, or a political ideology. It is not a question of reason being better or worse than religious faith. What is at fault is our use of higher causes to justify the harms done by our actions.

Science, religion, and the liberal arts have failed us because our capacity for empathy is weak compared to our capacity for self-serving. Freud understood this problem in his Civilization and its Discontents, but his solution, sublimation of the harmful tensions within us by making civilization’s greatest contributions, is not easy to do. Without effective regulation of our motives, we are limited to repeating (and justifying) our mistakes every generation.

Life Lines 89


Barbara McClintock won an unshared Nobel prize in Medicine in 1983. She was already advanced in age when she won that award and many others, including the MacArthur Award, a no-strings attached generous award given to geniuses. McClintock grew up in Brooklyn and went to Cornell for her undergraduate education. She liked botany and soon proved herself to be uncommonly gifted in cytology, the study of cell chromosomes and other structures in the cell. She worked exclusively in corn genetics and cytology the rest of her life. It was not easy for a woman to get a faculty job in those days and she held low paying jobs in Missouri and later at Cold Spring Harbor. This wasn’t too important for McClintock, because she never married and lived simply, spending most of her life in the fields caring for her corn and in her laboratory looking at the results of her genetic crosses and confirming her interpretations by careful study of the chromosomes under a microscope.

McClintock worked with a genetically difficult organism. When you munch on a corn kernel, it contains three tissues – a maternal tissue that has two sets of chromosomes (two sets is normal), a nutritive material that has three sets of chromosomes, and its own tissue, including the embryonic leaves, roots, and stems, that have two sets of chromosomes. Corn also takes some time to grow and at best McClintock could get two growing seasons a year. She also worked on problems that intrigued her. She was the first to show how chromosomes produce genetic recombination. She mapped all of the chromosomes in corn. She discovered a curious phenomenon that she called the breakage-fusion-bridge cycle that became the basis of interpreting radiation sickness from those who are heavily exposed to radiation, like victims of Hiroshima and Nagasaki. Her Nobel was given to her for something even more unusual. She claimed in the early 1950s that she had found genes that detached from chromosomes and inserted themselves elsewhere. She called them “transposable elements.” They were later found in bacteria and other plants and animals. They are now a major tool for genetic engineering and bring human genes into bacteria, mice, or sheep.

I heard McClintock give papers on her work when I was a graduate student but I didn’t understand the significance of her work. She didn’t have much opportunity to teach so her presentations tended to be very technical and difficult to follow for those not in corn genetics. When my wife and I honeymooned on Cold Spring Harbor, we got to know her well and she always had a cheery greeting when I passed her while she worked in the field. About 1970 she called me and asked if I wanted their reprint collection for my history of genetics studies. I drove out with an undergraduate student. “Have a lollipop,” she said, when we got there and then my student and I had a wonderful discussion with her on her idea about genetics.

McClintock had misgivings about a biography written about her. “It makes me feel like a cult figure,” she lamented and with reluctance she autographed my copy. She treasured her privacy and was one of those rare individuals who thrived on solitude and the pleasure of a life in science.

Life Lines 88


During the Vietnam war the US sprayed jungles to defoliate broad leafed plants and make visible places where Vietcong and their supporters would hide. Millions of tons of this mixture of two herbicides (2,4-D and 2,4,5-T) were used over a period of several years. After the war our veterans complained of symptoms and illnesses from exposure to agent orange sprays. The cold war prevented recognition of Vietnam until recently and thus a laboratory of contaminated soil and contaminated villagers was closed off to investigation by the US and its allies. The Vietnamese lacked the resources to carry out effective chemical and medical studies on their own population.

In 1983 I was one of a dozen or so Americans who met in Ho Chi Minh City with about 100 European and other scientists to discuss our work at an International Symposium on Agent Orange. I had studied 2,4-D and 2,4,5-T on fruit flies and found many biological effects. They were alone or in combination lethal at certain doses to the developing flies (as embryos and larvae). They inhibited egg-laying by the fertile females. They forced the larvae to crawl to their death before they were mature enough to undergo metamorphosis. Females (which contain more fat) were more drastically killed at sublethal doses and I would get bottles with almost all males emerging. I did not find mutations, gains or losses of chromosomes, or breakage of chromosomes.

The trip was arranged through the UN by our US representative (as an advisor since he could not formally act on behalf of the US government). I was not impressed by the Vietnamese data on birth defects because they had control values that were unrealistic. But they did have an incredible excess of molar pregnancies, which are implanted sacs lacking an embryo. These appeared among women in the sprayed regions and not among the wives of male veterans who returned to the unsprayed Northern cities and villages. I suspect that the dioxins or agent orange components caused the eggs to extrude a nucleus and when the sperm entered, a molar pregnancy formed. Since the male-only composition of these molar pregnancies appeared in print about two years after the conference, it couldn’t have been faked data based on prior knowledge.

Our veterans, and the Vietnamese, lost an opportunity to study the effects of these compounds in the food chain. Both 2,4-D and 2,4,5-T decay from sunlight and other environmental activities within a few years. Dioxins last longer but it has been more than 25 years since these sprayings took place.

Congress finally pressured the US government to compensate the veterans exposed to these dangerous compounds regardless of the strength of evidence for or against the harmful effects of these compounds. Officially we only recognize a skin disease, chloracne, as caused by agent orange exposure, but many reports of soft tissue cancers, and neurological damage have been dismissed as unproved or consequences of shell shock. When I spoke to veterans groups during the 1980s I was not convinced these men were the alcoholics, drug abusers, and malingerers many of their government critics claimed them to be.

Life Lines 87


About one in every 80 pregnancies results in twins. In the US identical twins are less common than what are called fraternal twins or non-identical twins. Geneticists prefer to call identical twins monozygotic because they arise from one fertilized egg. This makes fraternal twins dizygotic because they are just separate siblings who happen to gestate together. Twins are common enough to have inspired myths in every culture. Since the chances of being a singleton are so overwhelming, people ages ago had to explain something rare. They came up with some strange ideas. One was the belief that the woman had intercourse with her husband and with a deity, resulting in a demi-god and a mortal. If the deity was appreciated or feared, that could be a great benefit to the twins who would be given special favors or respectful distance. If the deity were an evil spirit it could be disaster for the twins (dumped into the river) and hard times for the mother who would be considered having practiced adultery with the evil spirit and thus she could be killed or banished.

These cultural traditions may have led to selection for or against twinning. Dizygotic twinning runs in the family but monozygotic twins are fairly constant around the world (about one in 400 pregnancies). A few years ago studies in mice showed identical twins were more likely to occur if the implanting preembryo was upside down (with the future embryo away from the uterine lining). We don’t know if this is true for humans. In Japan dizygotic twins are rarer than monozygotic twins and I suspect a past history of destroying twins in ancient Japanese culture.

In our century the incidence of twins is going up because infertile women are often given hormones to induce ovulation or, since the 1970s, they attempt in vitro fertilization and there’s about a 15 to 20 percent chance of having twins because three or four preembryos are implanted in this procedure to make sure that a pregnancy will occur. These twins are almost always dizygotic twins.

Identical twins have more risks during pregnancy than dizygotic twins. Dizygotic twins always have two separate membranes around each of the embryos or fetuses. Monozygotic twins in eighty percent of the cases, have a common outer sac and two inner sacs. The other twenty percent are indistinguishable from dizygotic twin membranes. Contrary to popular belief, most identical twins do not come from a divided egg that separates into two cells. They usually arise after implantation and involve the splitting of the preembryonic mass into two chunks. If this happens very late in the forming of the early embryo, conjoined twins may arise. We use the popular term, Siamese twins, for such children and they may be joined at the head, the abdomen, or the hips. If possible these conjoined twins are surgically separated. Identical twins may not look identical at birth. About 10% of them may be unequal in size, one looking ruddy and the other pale and emaciated. The smaller twin plays catch up and the two are usually the same size some six months after birth but in a few cases the difference remains for life. It should be no surprise that twin births have higher risks to mother and children than singletons.

Life Lines 86


Our cells, we have several trillion of them, each contain a nucleus with chromosomes and a surrounding blob of cytoplasm that contains organelles. Organelles do the work of the cell and each type is specialized. One of these is your mitochondria. They are unusual in many ways. They look like bacteria (prokaryotes) and some biologists believe they evolved from bacteria inside other bacteria some three billion years ago. They are usually taught to high school students as being “the powerhouse of the cell.” The phrase means mitochondria take the oxygen we breathe, burn up the food we eat, and give our cells the energy they need to tear apart or synthesize molecules.

Their origin from bacteria makes sense because mitochondria have their own DNA (genes) but the proteins that make up mitochondria come from both our nuclear genes and our mitochondria genes. We get our mitochondria only from our mothers. Our father’s sperm does not contribute any mitochondria to us. Geneticists call such a pattern “maternal inheritance.” The closest thing to it in our culture is Jewishness, which is passed from mother to child; which is why Jews consider the children of an interfaith marriage of a Jewish woman with a non-Jewish male Jewish but the children of a Jewish male with a non-Jewish female are not Jewish (unless they convert to Judaism).

Several years ago when the techniques for sequencing genes into their DNA nucleotides became possible, scientists sampled mitochondria from people in different continents. They compared the sequences and looked for mutant variations. About one such new variant shows up every 250,000 years. If an entire population has that variant it was brought in by a settler, a woman who is ancestral to all those alive today in that ethnic group. If the variant is present in only some of the people of an ethnic group, it arose much later. By comparing the variants around the world, the scientists believed they could identify the mother of us all, dubbed “mitochondrial Eve.” She came from Africa and she lived about 250,000 years ago. Other scientists are not as convinced that the story is this clear. All agree however, that mitochondrial Eve was not the first woman, just a woman who is our Ur-grandmother. All of her kin in Africa (perhaps in the hundreds of thousands or millions) did not end up contributing to our mitochondria.

What this implies is an African origin of our species (Homo sapiens) and the departure from there of our species some quarter of a million years ago to the Middle East, Europe, and Asia and onwards across the Pacific and over Alaska into the New World. Those of you reading this, unless you are of native American descent, are of more recent immigrant settlers to the New World.

No doubt molecular anthropologists will have better and larger samples to check out this hypothesis. Other supporting evidence makes it likely. When I visited Kenya a few years ago, after teaching my students on board the SS Universe about mitochondrial Eve, I mentally paid homage to that remarkable mother of five billion descendants.

Life Lines 85


When I was a lanky child, growing up in the Depression, I heard myself referred to as being all skin and bones. I wasn’t starving; it was just my genetics and the modest diet that my father’s wages provided. When I saw the first photos of Holocaust survivors in the newspapers, I learned what that phrase really meant to those deprived of food. We use up our stored fats and then go after our own muscles when we starve. Skin and bones are also connected by vitamin D. We make vitamin D from the cholesterol in our skin. Not all cholesterol is bad for us. To do this our skin uses ultraviolet light which we get from the sun. Where sunlight is meager, as in the winters of those who live in northern latitudes, not enough vitamin D is made through sunlight entering the skin. Those people have to get vitamin D from the food they eat and that’s usually seafood. Inland people in the past did not have access to such foods and when I was a child it was supplied by parents in the form of cod liver oil, a disgusting tasting fishy and oily substance.

Infants and children deprived of vitamin D cannot produce enough bone. Their bones become rubbery and deformed in shape. Such children had rickets. During the 1930s concern for children deprived of vitamin D led to federal requirements that milk be supplied with vitamin D. In those days the bottle caps used to boast that the dairy provided irradiated milk (the ultraviolet to convert cholesterol in milk being supplied by technology).

Much later, scientists learned that there is a relation between vitamin D synthesis and the amount of melanin pigment in the skin. The more melanin deposited in the skin, the less ultra violet enters. This makes good sense if people live in tropical areas near the equator where sunlight is abundant and intense all year round. Too much ultraviolet causes sunburn to people with light skin color. It also leads to skin cancers and melanomas which can be fatal. Dark skin is thus adaptive to those who live in equatorial regions. People who live in northern latitudes, however, found dark skin a disadvantage because it led to rickets which can be fatal in a world where physical skills determined survival. As humans moved out of their ancestral home in Africa some 200,000 years ago, their skin color was selected for more efficient ultraviolet absorption. Skin colors became lighter and normal bone growth followed. Thus both dark skin and light skin served their purposes over the millennia as humans settled the earth.

Life is filled with agents and substances that are both necessary for health and damaging to health. Fatalists take it on the chin and just ride their fates hoping for miracles to spare them harm. Scientists try to understand why things work the way they do and thus we can take charge of our lives and enjoy the benefits of vitamin D produced in our skins, the ultraviolet induced protective tanning, the natural skin color adaptive to our latitude, or a variety of sun screens to prevent those chromosome-snapping thymine dimers formed in our DNA whenever ultraviolet penetrates the barriers of our melanin and enters deep within our cells. Today dark skinned people living in the north are protected by diet from rickets and light skinned people living in the south are protected, if they use good sense while outdoors, from sunburn and skin cancers.

Life Lines 84


There are few authenticated life spans that have reached 120 years or more. When we do think of how long we will live, it’s usually a tempered reality that flits about 80 years or so and wishful thinking for most of us when we dream of living to be 100. Our views would be very different in times past. Most people born had a rough time making it past the first year of life. In fact, about half of all children born died in infancy until very recently and even in our own century there was a high infant mortality, similar to olden times, in some parts of the non-industrial world.

When people who prepare vital statistics prepare their annual accounts of births, deaths, marriages, abortions, divorces, and causes of mortality, they have to use a standard that is useful. One such device is a mathematical abstraction called mean life expectancy. You simply get the number of deaths at every age from birth and see how many die in each year and make an average. If, as is true for us today, most babies live to celebrate their first birthday, you’ll end up with 75 to 80 years as our 1990s level of mean life experience. If this were 1900 you’d conclude it is about 50 years. If you went back to Philadelphia in 1776 it would be about 30, a figure not very different from estimates based on gravestones in Roman colonies.

Because mathematical abstractions make sense to mathematicians and rarely to anyone else, the public has a peculiar view that walking in Philadelphia in 1776 would give us crowds of children and teenagers and some robust 20 year olds but relatively few middle aged and old people. That isn’t mean life expectancy, that’s fantasy. Except for the historical differences in clothing, transportation, and buildings, Philadelphia would look as it does today – kids and teens and young adults and lots of middle aged and old people. What you won’t see is the amount of grief most married couples experienced having children. About half their babies died of pneumonia and diarrhea.

There was another myth we believed several years ago and which I still encounter from my students. Certain regions of the world near Tibet (a sort of Shangri-La), in the Caucasian mountains, or in the Andes allegedly have such good health that people who live to 100 are common. According to the myth, they either live on yogurt, are vitalized by high altitude air, or enjoy a vegetarian diet. When I was a visiting professor at Minnesota, I got to meet Zhores Medvedev, a then visiting Soviet dissident and scholar. He studied centenarians in the Caucuses and found that they were no more abundant than in other parts of the USSR. What gave them their long lives was the absence of birth certificates and the awards (including one’s portrait on a postage stamp), producing a mysterious reduction in 90 year olds and an excess of self-proclaimed 100 year olds!

That’s sad news for wishful thinking and our mean life expectancy throughout the twenty-first century is unlikely to exceed 90 years.

Life Lines 83


Herman Joseph Muller (H.J. Muller in publications, Herman to his friends before 1940, and Joe to his friends after that date) was my graduate school mentor and recipient of a Nobel Prize in medicine in 1946 for first discovering that x-rays induce mutations. He is best known as the founder of the field of radiation genetics.

Muller (1890-1967) was a third generation American who grew up in New York City and attended Morris High School in the Bronx. He attended Columbia University on scholarship and joined the new school of fruit fly genetics founded by Thomas Hunt Morgan, himself a Nobel laureate (1933).

I wrote Muller’s biography some years ago because I thought his life unusual for a scientist. In an era when scientists avoided the public, Muller lived a life of controversy. He was a student socialist, a tough-minded idiosyncratic scientist who did not hesitate to tell off his own mentor and senior scientists when he felt they were wrong. He was competitive, energetic, and committed as a scholar to “the winning of the facts.” He had international stature when he was in his 20s. He brought the first fruit flies to the USSR. He edited a Communist-front student newspaper (The Spark) on the University of Texas campus where he did his Nobel Prize experiments. He denounced American eugenics as racist, sexist, and based on spurious elitism. He went to Germany on a Guggenheim shortly after attempting suicide. He fled Hitler and went to the USSR for five years and lived to witness the arrest and execution of two of his students. He escaped by fighting in the Spanish Civil War.

I went to Indiana University to study with Muller. He was short (5 foot 2 inches), bald, and energetic. He worked seven days a week. He demanded the same. He argued every sentence I wrote and demanded precision and better evidence for my ideas. He had risked his life in three countries denouncing tyranny and lost his job at Texas through his infatuation with Communism. He fought to protect the public from radiation damage. Some people attract trouble and thrive on controversy. Muller was one. He took on capitalists, communists, fascists, Cold Warriors of the left, and Cold Warriors of the right. He said he’d rather be dead than Red. Throughout his ordeals he held steadfast to two ideals. He searched for the truth in genetics and sought to learn all he could about mutation and the gene. He also kept reviving a belief in the potential wisdom of humanity to use the knowledge of genetics to improve our lives and to bestow on future generations a healthier heredity than we ourselves had.

Muller was a gadfly. He belongs to the tradition of a Socrates, a Thomas Paine, or a Martin Luther King,Jr. They are often reviled in their lifetime but revered for their contributions to humanity. For every loving Mother Teresa there is a pugnacious Henry David Thoreau, ready to rub our noses into reality. We need both kinds of saints.

Life Lines 82


Children love dinosaurs. They are extinct relatives and their history was played out long ago so they can’t threaten us. They roamed on earth tens of millions of years ago and most disappeared relatively rapidly some 60 to 70 million years ago, most likely from a collision with a meteor. Most dinosaurs we know from their fossil bones. A few have left imprints of their skin and other remnants behind, including the shells from which they hatched. There is a lot of debate about their physiology, most considering them warm-blooded rather than cold-blooded. There is also debate about their behavior, some arguing they cared for their young after hatching and others arguing for a pattern of dump the eggs and walk away.

The American Museum of Natural History in NY City has recently completed an extensive reorganization of its dinosaur collection and placed them in two of its four connected wings on the origins and variety of the vertebrates. We are vertebrates and belong to the mammals. Our immediate predecessors look more like dinosaurs than mammals. As we enter the first hall of the exhibit we can choose a ten minute film to introduce us to the evolution of vertebrates or a series of paintings that unfold the hundreds of millions of years carved into geological eras. I was immensely pleased by these exhibits. It comes as a shock to see the earliest ancestors of fish, the placoderms, having not teeth but tooth plates, like jagged and irregular chunks of sheet metal that would easily make mince meat of the invertebrate flesh they encountered.

I was surprised to find that sharks came from bony fishes and not the other way around. I marveled at the variety of ways our limbs developed. Some of these early ancestors had up to eight digits to a flipper or foot. The fingers had up to ten phalanges (if you bend your fingers and count, you’ll find three in all except your thumbs). We are surprised that dinosaurs are two or three toed, as if designed by Disney, whose cartoon characters routinely uncrowd their hands with a missing digit.

The exhibits guide us with arrows and mosaic or painted paths, a sort of Yellow Brick Road adventure, as filled with forks and surprises as those Dorothy and her friends took to Oz. I am a passionate museum goer. I don’t develop museum fatigue. I take notes. The students I take with me often wilt and disappear reappearing two hours or so later when we gather to board our bus back to the university. I am used to that and hope a few will read the fine print of the exhibit cards and thrill as I do to see that the curator of the exhibit has demoted reptiles to a cultural term and not of scientific worth. The dinosaurs are part of the saurosids, along with crocodiles, lizards, snakes, turtles, and birds. Birds? Those lovely goldfinches at my feeder? Could they be part and parcel of the saurosids and a bud off the dinosaur branch? It’s controversial, of course, as classifications based on a spotty fossil record often are, but how startling it is to see their two skeletons side by side, reduced to the same size, looking so much like siblings.

Life Lines 81


Males have an X and a Y chromosome plus 23 pairs of chromosomes that are found in both sexes. Females have two X chromosomes. The X and Y chromosomes are called sex chromosomes. The Y chromosome is not essential for life (any female is living testimony to that inference). But it sure is needed to make a male. The Y chromosome has a gene that converts a neutral embryonic future sex organ (the gonads) into testes. The testes then make hormones that produce the male sexual apparatus. The absence of that gene on the Y normally occurs when the fertilized egg has two X chromosomes and the gonads become ovaries and the absence of the male hormones lead to female sex apparatus formation. Sometimes gene mutations can mess things up leading to XY females or apparent XX males.

The Y is found in half of a male’s sperm. Those are the sperm that produce sons. The X is found in the other half of the male’s sperm and they produce daughters. Biologists know that it is the male who determines the sex of his children but for generations many women were punished for not giving husbands sons!

The genes of the Y stay together but the genes of all other chromosomes have an opportunity to switch bits of their chromosomes when sperm or eggs are made. Since fathers pass their Y chromosomes only to their sons and these genes always stay together, the mutations that arise in the Y chromosome will stay there unless they lead to infertility. That is not at all unusual because many genes for making sperm are found on the Y chromosome.

The sequence of most of the genes for our Y chromosome is known because it is a small chromosome. Samples from people around the world in different continents have been studies and there is no variation except in Africa! Perhaps larger samples will reveal some differences, but the rate of change of normal to mutant is relatively low compared to some other genetic systems in our cells. This implies that our common Y ancestor or Ur-grandfather (whom we call Y chromosome Adam) left his African homeland with his mitochondrial Eve partner about 250,000 years ago and none of his European, Asian, or New World descendants have established Y chromosome variations that survived.

Just as mitochondrial Eve, our common ancestor of humanity, had kin in the thousands, so too Y chromosome Adam had lots of male kin. They just didn’t luck out to get their Y chromosome to us. When we study pedigrees, we often note people who keep following their family name back. They are following their father’s Y chromosome as far as it goes. Thus J. Pierpont Morgan, the financier and T. H. Morgan the Nobel Prize geneticist, share both a common last name, a relative who stepped off the Mayflower, and a common Y chromosome. They share very few of their other genes from that Mayflower ancestor.

Saturday, December 11, 2010

Life Lines 80


Each generation has its own music, art, literature, and other ways of seeing and interpreting the universe. We seek nevertheless universal truths that are fixed and that will serve us a guide through life. For most of humanity it is found in a religion, one of several hundred contradictory religions, some believing in the existence one god, some in many gods, and some in no gods. The difficulty with these religious guidelines is their ease of reinterpretation. Each generation is selective in what it considers important to its own values. “Thou shalt not kill” has a myriad of exceptions for those who justify capital punishment, collateral deaths in bombings, or the vaporization of non-combatant men, women and children in Hiroshima and Nagasaki. In the past the justified killings included counterfeiting, blasphemy, atheism, pick pocketing, mutiny, and heresies of innumerable kinds. Falling asleep while on sentry duty was punishable by death.

It is not just commandments that we violate and justify; we reinterpret everything, all the time, because each generation has a different universe to live in. Old values are stretched to accommodate new priorities. In the 1940s I listened to radioevangelists condemning the sin of Mammon worship (materialistic wealth). Today televangelists praise the acquisition of wealth and no longer ask their wealthy donors to struggle about squeezing through a needle’s eye. We don’t condemn keeping up with the Joneses; we convince ourselves that we want the best for our children or our families.

Science also reinterprets the past. It does so with a different motivation in mind. It seeks to understand the physical universe of atoms and their activities from the subatomic to the galaxies of the universe including life on earth. Since modern science began with Galileo’s use of the telescope to examine the sun, moon, and planets we have had an unending series of understandings of how the physical laws of the universe work, how molecules are formed from atoms, how heredity works, how infectious diseases arise from germs, and how a fertilized egg eventually becomes an adult being. The applications of science necessarily involve values; and science is often abused by making weapons of mass destruction, by pollution from its by-products, and by inadequate regulation. Here the failings of applied science are no different from the failings of humanity more familiar to the past – bribery, influence peddling, nepotism, cronyism, greed, theft, and betrayal. Whoever harms another person, intentionally or not, justifies that behavior as being done for a higher cause. That higher cause can be religion, patriotism, one’s family, or a political ideology. It is not a question of reason being better or worse than religious faith. What is at fault is our use of higher causes to justify the harms done by our actions.

Science, religion, and the liberal arts have failed us because our capacity for empathy is weak compared to our capacity for self-serving. Freud understood this problem in his Civilization and its Discontents, but his solution, sublimation of the harmful tensions within us by making civilization’s greatest contributions, is not easy to do. Without effective regulation of our motives, we are limited to repeating (and justifying) our mistakes every generation.

Life Lines 79


Darwin was the first to sketch a simple branched diagram showing how life is connected through evolution. By the time I was a teenager I was enjoying phylogenetic trees that classified all living things into two kingdoms –plants and animal. Some fifty years later that classification has given way to 96 phyla distributed among three domains. The domains are given the technical names eukaryotes, eubacteria, and archaebacteria. You and almost everything you know that is living are eukaryotes. Your cells have nuclei. But bacteria and archaebacteria have a different structure—they do not have nuclei and their cells are much smaller. That cell structure is called prokaryotic (next time you get a strep throat, think of prokaryotes gathering in multitudes reddening those tissues).

In 2006 scientists compared the complete genome sequences of 191 species that shared in common some 31 genes. There were 11 multicelled animals among these 191 and they represented the major animal phyla (worms, jellyfish, mollusks, arthropods, vertebrates, echinoderms, etc.). Most of the completed sequences were from prokaryotes. The most familiar domain of the prokaryotes belong to the eubacteria (the ones dealing with the germ theory, with spoiled food, rotting carcasses, and some commercially useful bacteria that make vinegar and a variety of cheeses, and other dairy products). The ones we almost never encounter live in extreme environments such as ocean vents, geysers, and sometimes miles down in the earth. The reason they are put into two domains has to do with their organization of their genes. The archaebacteria have split genes as do the eukaryotes but they have a prokaryotic organization. Most prokaryotes are killed when scalded but archaebacteria flourish in hot water that can be very hostile. A few of the eubacteria are also capable of thriving in hot water or extreme environments and they are among the oldest of the forms of life on our evolutionary tree. The archaebacteria arose from the eubacteria and the eukaryotes arose from the archaebacteria.

The phylogenetic tree which relates the genomes to their mutational differences, as one form of life arose from an earlier one, gives a picture strikingly similar to the phylogenetic trees constructed from the fossil record. The age of these ancestors is also determined independently by isotopic analysis of the rocks they are in and the mutational differences among their common genes. Those who think evolution is “just a theory” have a lot of explaining to do because that relation between complexity and time fits evolution and not special creation in any of its forms. The evolutionary theory based on the older fossil record predicted the molecular phylogenetic tree would resemble it in its major features and it did. Science makes predictions and the data lets the scientist see if the theory still holds. It does for the phylogenetic theory.

What is remarkable about this computer generated phylogenetic tree is that new genome sequences can be added as all of the 96 phyla are eventually sequenced and the tree will become more elaborate. Just as a genealogist finds family members in the thousands when dedicated to searching for one’s ancestors, the scientist finds the major family members of all life on earth. Some day a fourth domain, the viruses, may be connected to the first and most ancient cells. We are kin to everything alive

Life Lines 77


My ninth grandchild arrived June 22, 1998 in Pasadena, California. I was visiting my closest friend, Dr. Peter Gary, a composer in Victoria, British Columbia. He is a Holocaust survivor and had studied with Kodaly and Bartok. My wife, Nedra, was already en route from Vancouver to Los Angeles when baby Maxwell arrived a week early. His mother, Lyn Yasumura, MD is an obstetrician and this was her first child although she has delivered over a thousand babies for other women. His father, Anders, is finishing his Ph.D. in structural engineering at Caltech. Anders and Lyn attended Ward Melville High School in Setauket.
Baby Maxwell, you are my mother’s 52nd descendant. She was born in Bound Brook, New Jersey of immigrants from Tarnapol, in what is now the Southwestern Ukraine. You are my father’s 17th descendant. He came from Stockholm, Sweden and settled in New York City after a few years in the merchant marine. You have eight cousins on your father’s side and none yet on your mother’s side. You are a melting-pot American who combines Swedish (one-eighth) Japanese (one fourth), Ukraine (one eighth), German (one fourth, English (one tenth), Welsh (one percent), Scottish (one percent), and French (a trace) ancestry. Your ancestors are Lutheran, Baptist, Jewish, Huguenot, Catholic, Unitarian, and Buddhist.
Four living relatives also have your Y chromosome. Three relatives have your mitochondria. You have about 100 genes (out of 25,000) of your ancestor, Andrew Babcock, who helped make the links of the great chain that stretched across the Hudson River near West point to prevent the British navy from supplying its Canadian forces during the Revolutionary war. Seven generations ago, your ancestor, Israel Dock Johnson, fought for the Union during the Civil War with his Indiana regiment and he survived the rigors of a Confederate prison camp by digging up and eating raw sweet potatoes. You have about 400 of Dock Johnson’s genes. One of the slaves freed during the Civil War was the grandfather of Evelyn [Billie] Hawkins, whose last name is now your middle name. She was your father’s fifth grandparent and she had adopted our family before your father was born.
You bring together by your birth, four very different families. Your Japanese-American grandfather, a professor and physiologist, was American-born and raised in New York and California until World War II when he was sent with his parents to an internment camp in Idaho. Your maternal grandmother, a college administrator, was born and raised in New York of German-Americans whose ancestors lived many generations in Virginia. Your paternal grandfather, a professor and geneticist, grew up in the slums of New York. Your paternal grandmother, an in-vitro fertilization embryologist, grew up in the small towns and farms of Northern Indiana. What we all have in common is our designations as Americans.
From yesterday’s immigrants to those who have lived in North America for a dozen or more generations, we have enjoyed the benefits of freedom (sometimes denied) and opportunity (sometimes thwarted). Enjoy that good fortune, Maxwell, and celebrate the many components of your ancestors who each helped make America the world’s most admired concept.

Life Lines 76


Science tries to understand the universe from the very tiny (atoms and their particles) to the very large (galaxies and their formation). It limits itself to the material world (the world that consists of matter and energy) and it uses reductionism as its methodology. This means it assumes complex objects can be taken apart into their components and reassembled to show that all of the components are accounted for. It works by a process called incrementalism – knowledge is built up bit by bit over generations to work things out that are very complicated like cells or macromolecules, or the means by which stars generate light and energy. It relies on technology because as humans we are limited to our senses and our eyes do not see as far as telescopes or distinguish the minuscule as effectively as microscopes. Nor can our unaided senses separate out molecules from one another as effectively as chromatography. Where possible scientists test things by designing experiments. They use reason as a tool to look for contradictions and construct theories from myriads of facts.

Religions attempt to relate how humans should live with each other and find meaning in the universe. Most religions invoke the existence of a God to justify that meaning or purpose in life. This requires a reliance on authority, sometimes scriptural (like a Bible or Koran) or the hierarchy of the religion (as in the primacy of the Pope for Roman Catholics). It also relies on tradition especially for the practice of rites or other obligations associated with the religion from clothing to foods to rituals. Those involved in a religious community accept these aspects through faith. Some features of the components of a religion are derived from revelation, a supernatural source of knowledge transmitted by conversation with the divine or from dreams and other sources. The totality of shared beliefs in any one of hundreds of different religions can be described as its creed or set of faith-based beliefs.

Religions and science collide when they discuss the origins of the universe, our galaxy, our sun, our earth, life on this earth, and human life. Most religions have some form of narrative of how these components of the universe arose. We call those narratives myths when referring to dead religions like those of ancient Egypt, Mesopotamia, Greece, and Rome. They also collide when natural events (such as evolution or the individual life cycle) are interpreted by religions as being guided or drawn to some ultimate purpose. Science also interprets disasters like earthquakes, hurricanes, floods, and volcanic eruptions by relying on factors such as temperature changes in the ocean, plate tectonic dynamics, the melting of a winter’s mass of snow and ice, and the erosion of rock by molten lava under pressure. Some religions prefer to look upon these as punishments meted out by God to chasten the unfaithful. All natural processes, to them, are reflections of a divine will. Science also does not invoke the miraculous or supernatural processes of any kind. Most of humanity can keep these two different systems as meeting different needs, which is one reason science continues to flourish and its practitioners are not rounded up to be burned at a stake. A small portion of humanity, alas, sees science as a threat to the faith of its future generations, a view that reflects its insecurity.

Life Lines 75


My mother was a paranoid schizophrenic. She was institutionalized when her first marriage failed and her two children were placed in an orphanage. She was released after three months and about a year later met the man who became my father. I knew my mother was different from other mothers because of her strange behavior. She would sometimes get off a subway and wait for another train because she was convinced someone was staring at her or talking about her. She would sometimes pull my brother and me out of a movie before it was over or out of a restaurant before we finished our meals. Sometimes she would punish a waiter by smearing food on the table. She had fights with our neighbors and sometimes the police had to be called. She fought a lot with my father. In today’s world some neighbor would have intervened and I might have ended up in a foster home (the shift from orphanages to foster care took place during the 1930s). This is what I would have missed: When my mother was not in one of her paranoid moods, she was very loving. My older brother was born with a congenital heart defect (inoperable in 1929 when he was born) and given six months to live. He lived because our mother protected him, always having us live on a ground floor and rarely farther than a block or two from a school where we attended. Instead of our being unsupervised in rough and tumble neighborhood play, our mother took us to the Metropolitan Museum of Art or Museum of Natural History almost every week during the summer. When not in museums she would stop at art shops and buy us watercolors or pastels and paper to do artwork at home. She would stop in bookstores and get us books. She took us to Central Park, Prospect Park, the Bronx Zoo, or cooled us off during heat waves by having us ride back and forth on the Staten Island Ferry. Everyday she took out her violin and played an hour of classical music (she was particularly fond of Fritz Kreisler’s renditions). In the 1940s she began to make a supplemental income by becoming a street musician. She took enormous pride in my brother’s and my activities and successes in school. She let us read anything we wanted. She tolerated the messes we made and never scolded us for smearing paint on the walls or scribbling with a pencil as long as we were engaged in creative activities. To protect my brother’s health she saw to it that I never learned to roller skate, to ride a bicycle, or to swim so that I would not tempt him to exert himself.

In my teens my mother would save her change from playing the violin, board a train to California, visit her daughter in San Diego, and return with only a small bag for her clothes and her violin. When she got hungry, she would get off during a rest stop at a station, play her violin, and when she had enough to buy a meal, return to her train. I learned from my mother that not everything in life has to be planned to perfection and that humans, however flawed, have remarkable capacities for survival and for obtaining a satisfaction out of life. I learned that adventure and novelty did not require wealth to experience. I also learned from her that taking risks and failing was more frequently outweighed by the successes coming from taking those risks. Eventually my mother’s paranoia worsened and she became a threat to her survival, refusing to eat because she believed her food was poisoned and I had to go through the horrific experience of committing my own mother. Remarkably, she bore no resentment and blamed my act on her imagined enemies who forced me to commit her.

Life Lines 74


I thought it would be helpful to prepare a series of Life Lines articles on the sciences that directly applies to issues of importance to us. I do so because science literacy is appallingly low. In a study in Europe, 40 percent of adults did not know that tomatoes contain genes. They thought genes were artificial and introduced into genetically modified foods; natural foods being gene free. This misunderstanding comes about because science is poorly taught, science is not taught, or society in general looks upon science as so specialized as to be irrelevant to their concerns as citizens. This public ignorance of science is just as bad in the United States. I would argue that this phobia against science is dangerous to our health, threatens our survival, and leads to an impoverished view of the universe as well as how we see ourselves. The ten topics I will present are:
• Cancer arises from a single cell and takes decades to produce symptoms
• Radiation causes two types of changes in chromosomes, both no good
• Our minds are a product of our neurons
• Some chemicals produce birth defects by damaging the embryo
• How one things leads to another—the germ theory produced population increases which produced the birth control movement which produced an aging population
• How genetic services enable parents to reject fatalism in their lives
• How science helps the infertile to have children
• Why biological diversity involves more than loss of exotic species
• Climate change has both natural and human contributions
• Global awareness is needed for our stewardship of the earth we live in

I will conclude the series with a number of recommendations about science teaching at the K-12 and undergraduate college level as well as some recommendations about how science can be more effectively presented by our media.

I believe science ignorance is too dangerous for the highly technical world in which we live. When we rely on luck, superstition, prejudice, shallow values, or a trust that our legislators and leaders are knowledgeable we invite a Pandora’s box of troubles. Ignorant and fanatic people can use the tools of science to do great harm. Unfortunately, even people of good will if they have a very limited understanding of science, may contribute to abuse of their own bodies and the world we live in. This is as true of conservatives as it is of liberals, of Republicans or Democrats, or of the rich or the poor. We do not have to be a nation of scientists, but we should know some of the ways science works in the same way most of us know Shakespeare was a playwright, Mozart was a composer, Picasso was a painter, Thomas Jefferson was our President, pizza is an Italian food, Tiger Woods plays golf, and Marilyn Monroe was an actress. We can appreciate the arts and humanities without being creative in any of those fields. If science is properly presented in the context of the liberal arts, it can be assimilated by most of humanity.

Life Lines 73


When we are very young we have limited experience of death, and for most children it hits home when a grandparent dies and they sudden realize they are mortal. For household pets like cats or dogs that recognition of death may never occur and in all likelihood they live their lives without a sense of being mortal. If small animals had a sense of mortality it would be very depressing. Imagine being a mouse and knowing that your mean life expectancy is two years. Of course, length of life is relative. We don’t feel like mice because Sequoia trees live, on average, two or three thousand years. Even a 250-year-old Galapagos tortoise does not shake our sense of fulfillment in a life expectancy of 80 to 90 years. Many insects live only a matter of days or weeks and it takes a stretch of our imaginations to imagine being fulfilled in such a short life cycle. As humans we can cope with our death by assuming (as most of humanity does) that there is a life after death either in the form of a resurrected body and mind or a disembodied mind existing out there (again, for most of humanity, in some sort of heaven or hell). There is an alternative way of looking at mortality and that is stoicism. That is a philosophy I learned about reading the Enchiridion aloud to a blind high school teacher who became, without my knowing it, a private tutor. I read classical literature and “great books” to him, an hour before classes began, for several years. The Enchiridion was written by Epictetus, a handicapped Roman slave, born with a deformed leg. He taught that our life could be shaped by those events we had little or no control over (our heredity, our status at birth, wars and other calamities, or even good fortune) and those that we did have control over (our moods, how we behave toward others, and the ideals we set for ourselves). I liked that attitude and it has served me well over some 60 years of life after learning it.

Biologically, death is essential for life to evolve or even continue. If we did not die the world would be unable to provide food, room, or even oxygen for us to exist unless we gave up our desire to reproduce. Death trims the population to a sustainable size. It also fosters variations to come into being that might otherwise be repressed. Younger generations of humans do things differently than their ancestors. Their values change, their knowledge changes, their priorities differ. Older people are stuck with their habits and traditions. They often stand in the way of a youthful generation that rejects the values of the old. This is why conservative thinking tends to go with older age. Ironically the radicalism of a youthful generation is often perceived as the conservative past for the next generation. But death does not visit the old alone. It also sifts through our genetic compositions and those with inefficient immune systems or those with genetic disorders or conditions that limit their survival may fall short of our species’ life expectancy. Biologically this may make sense, but emotionally it is difficult to accept the mortality of those we love, revere, or consider models for our lives. In a way it is good that most plants and animals are unaware of death. Nature plays out its vicissitudes, as lawyers liked to note in the wills they prepared for us, and harvests through death the failures who leave fewer offspring behind. Fortunately, for humanity, we have learned to extend our life expectancy and patch up our failing organ systems, but sooner or later death wins. The machinery of life sooner or later wears out. My stoicism, so far, keeps my ideals alive.

Life Lines 72


Until the 1660s the smallest object human eyes could see was a mustard seed or speck of dust. That changed when Robert Hooke devised a microscope and described the structure of cork bark as made of a myriad of what he called cells. He had no concept that life was composed of cells; that came later, when German scientists in 1838 described plants and animals as communities of cells. By the 1860s a new field of microscopic anatomy (called histology) studied tissues and related them to function as well as to disease. With this knowledge came Rudolph Virchow’s cell doctrine. Every individual’s life has its origin in a single cell.

When we contemplate that the one cell that gave rise to our present self has now produced 100 trillion cells in an adult body, that is a staggering realization of the multitudes of cells we contain. Scientists quickly learned that the tissues were related to function. Some cells are contractile like muscle. Some secrete digestive juices like those that line the insides of our guts. Some are sacs of hemoglobin, like our blood cells. This tells us that our body is a community of specialized regions carrying out different functions. It also tells us that because we are unaware of our cells unless we see them under microscopes, we tend to ignore them. This makes us vulnerable to agents that alter cells (usually the genes they contain) and result in tumor cell formation. We are also vulnerable to agents that alter reproductive cells and produce birth defects if not in our children then in some future generation that gets the damaged gene causing a birth defect. Because our education for the past two or three generations has largely minimized the ways our cells can be damaged, we are not likely to protect ourselves adequately from harm. That will change as science penetrates our education and our culture more forcefully in the coming generations. It took a half-century or more before the germ theory penetrated public consciousness and made us aware that there are germs that can cause illness or death. Yet there are still those who believe infectious diseases are imaginary and that all illness arises from loss of faith or is meted out by a fate beyond human understanding.

But there is also a pleasurable side to knowing we are composed of cells. It enriches our knowledge of life and how it works. It stimulates our curiosity to know how cells change in composition to acquire different functions as we shift from being a fertilized egg to an embryo, fetus, child, and adult. It may challenge our sense of who we are when we consider that it is possible to take adult cells, shift them into an embryonic state, and produce a clone or individual who is an identical twin of the individual who contributed that cell. Twins who are a generation apart may not be the same in personality and interests as twins raised together from birth. Right now that cloning is done in dogs, sheep, or other mammals but it is very possible that someone will do this for humans. In our more morbid science fiction imaginations we can imagine a world-controller who produces a nation cloned of himself and perhaps his wife and arranges the sterilization or death of all others. It freaks us out, but it is not likely to happen, any more than having Congress and a President ordering the sterilization of all Americans who cannot trace their ancestry to the Revolutionary War.