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Q5: Are cockroaches resistant to radiation?A: I have been told that cockroaches are more resistant to radiation and in a world nuclear war, only the cockroaches would survive. But I have not seen any publication that discusses it with any credibility. I can give only an opinion of my own. I have irradiated cockroaches and constructed killing curves for them using gamma irradiation. I have not compared their resistance to radiation with any other organism using the same equipment and thus can not comment on any relative resistance based on hard data.My opinion is that insects in general would be relatively resistant to radiation compared to non-insects, or non-arthropods more strictly. The lives of insects and other arthropods revolve around their molting cycles. During a molting cycle the cells of the insect divide usually only once. This is encoded in Dyar's Rule, i.e. insects double their weight at each molt and thus their cells need divide only once per molting cycle.Now it just so happens that cells are most sensitive to radiation when they are dividing. That is the basis on which radiation is used to kill cancer cells. Cancer cells tend to divide more often than the other cells of our body. For a given dose of radiation you will kill more cancer cells than normal cells. With the right dose with the right cancer you can kill all the cancer cells while only killing some of the most rapidly dividing normal cells (i.e. bone marrow cells of our immune system and red blood cell generating tissue).Now if a typical cockroach molts at most once a week, its cells usually divide within a 48 hour period within that week. That means that about 3/4 of the cockroaches would not have cells that are particularly radiation sensitive at any one time. If a killing radiation is endured by a cockroach and human population, then 3/4 of the cockroaches might survive while none of the humans might survive since our blood stem-cells and immune stem-cells are dividing all the time.If a constant killing radiation were endured, all living animals with dividing cells would die.