|MadSci Network: General Biology|
There are a couple of reasons why insects (including our friend the cockroach) are more resistant to the effects of radiation than we are. Specifically, insects are less complex organisms, they have less genetic material, and they don't live very long. I'll explain these below. The more complex an organism is, the more sensitive it is to the effects of radiation. Part of the reason is that more complicated things have a lot more that can go wrong. For example, think of the difference between a brick and a watch. It's hard to hurt a brick because all it really does it sit there. It is simple and it has a simple function. It can take a lot of punishment and still do it's job of holding up a wall. On the other hand, a watch is much more complicated and a simple drop can break it because there are so many fragile and closely-machined parts. Similarly, cockroaches are simpler organisms than we are with less to go wrong and they can take more damage before they "break". Because of our added complexity, we have more genetic material. Part of the damage radiation can do is to cause mutations in our DNA. Like with target shooting, you have a better chance of hitting something if there are more targets. Cockroaches and other insects have relatively small amount of DNA, making it harder to hit and damage. Finally, cockroaches don't live that long, so there's less chance to have anything go wrong. In humans, cancer is a multi-stage process that takes 10 years or more to occur after exposure to radiation. Cockroaches just don't live long enough to develop cancer. Actually, humans didn't usually live long enough to develop cancer until rather recently. You might be interested to know that, although the overall number of cancers has increased, when we adjust that to account for the fact that we live a lot longer than we used to, the age-adjusted cancer rate is not very different today than it was 100 years ago. I hope this answers your question. For more information, I'd suggest reading any of the reports by the United Nations Science Committee on the Effects of Atomic Radiation (UNSCEAR), reports by the National Academy of Science on the Biological Effects of Ionizing Radiation (BEIR reports), or basic textbooks in radiation safety. One particularly good one is written by Herman Cember and is called (I think) Introduction to Health Physics. --------------------------------------------------------------------------- Andrew Karam, MS, CHP firstname.lastname@example.org RSO, University of Rochester http://www.rochester.edu/Admin/EHAS/rshpage.htm
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