Sunday, December 5, 2010

Life Lines 70


People buy lottery tickets because they hope that a rare event, usually measured as a ten million to one likelihood will make them instant millionaires. For that reason, I have never bought a lottery ticket. The odds are too far fetched. It is true, nevertheless, that someone out there will be a lucky winner, but no matter how you try to choose your numbers, my rational mind says it is not cause, just luck, that one particular person has chosen the right ones. There are lots of more likely, although rare events, that can happen. The chances of a severe (Category 3 or 4) hurricane hitting Long Island are about once every 75 years. The chances of a volcano exploding in the USA south of the Canadian border are about once every 100 years. A severe earthquake in Los Angeles is about once every 50 years. A severe earthquake in St. Louis is about once every 500 years. A major meteor impact causing massive destruction of life is about once in 100 million years. Having a child with an extra chromosome 18 is about once in 3000 births. The chances your baby will be included in Who’s Who in America is about 1 in 1500. The chances your baby will win a Nobel Prize is about 1 in one million for an American.

Some odds are closer to home. The chances of having a baby with a birth defect requiring medical attention are about 1 in 20. Turn that around; the chances of having a healthy baby are 19 out of 20 (95%). Sounds better, doesn’t it? Pessimists will focus on the 1 in 20; optimists will go with the 19 out of 20. But society will experience enough of the babies with birth defects to keep hospitals and their staff busy all year round. When events are relatively uncommon but not so rare as to be remarkable, we have to respond as a society to the reality of the numbers because hundreds or thousands of babies may be born in or referred to large hospitals serving many smaller communities. When I was on a sabbatical at the University of Minnesota learning human genetics by going on rounds with pediatric fellows to see birth defects, I realized that rare events are common events in environments like tertiary care hospitals. Today we think of gene mutations, chromosome disorders, anoxia, infections, and many other reasons why a pregnancy may lead to a child with a birth defect. Go back 400 years or more and most of those defects had no names. If the baby looked abnormal, society blamed an evil eye, a shock to the mother witnessing a traumatic event, a curse on the family for the transgressions of a distant ancestor.

For very rare events we don’t prepare or put much time or resources into dealing with them unless we have a technology that we can confidently use to prevent such disasters. We could use our rocket science to nudge an asteroid coming to our earth. But if the asteroid is very large (think of the Shoemaker-Levy comet whose chunks splattered the surface of Jupiter) it is unlikely we could protect ourselves. We cannot presently cool the ocean to prevent hurricanes from forming or deflect them in their path to a major city. We cannot prevent earthquakes from doing severe damage to vulnerable cities but we can produce more strict building codes to prevent a heavy loss of life.

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