The Evolution of Virulent Diseases

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Somatic evolution of cancer cells might be an interesting topic; however, to be honest with you, I think that you may find another evolutionary topic even more interesting. It concerns the evolution of virulent diseases. It's a very fascinating topic and you should be able to find lots of information on it.

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A number of years ago, evolutionary biologist Paul W. Ewald wrote a fascinating research book entitled "Evolution of Infectious Disease." He covers the effect of water contamination, war, mosquito vectors, etc. And of course, he spends a fair amount of time discussing HIV/AIDS.

For example, for HIV, he traces the virulence, i.e. the severity of the strain, of HIV from the 1960s to the present and concludes that social pressures are the primary causative evolutionary agents for the highly virulent strains of HIV that exist today.

The main thesis of his work is this: infectious diseases, whether parasitic, viral, or bacteria evolve according to selective pressures. There is nothing new in that hypothesis as it goes all the way back to Darwinian natural selection. However, he has applied this understanding of microevolution to develop a hypothesis that explains why and how some strains of infectious disease become highly virulent and others become quite harmless. The answer has to do with selective environmental pressures. It's realy quite fascinating.

Nature selects those members of a population that can survive well and leave lots of progeny. This pertains to viruses like HIV too. Is there a universal recipe for reproductive success? No, different environments favor different traits. Therefore, if there is one particular environment, that will favor one particular strain, if there is another type of environment, another strain will be favored...and so ...