Wednesday, April 01, 2009

Human evolution at work

Examine carefully the causes of death for infants, children, and teenagers, for these are the deaths that evolution cares about: their DNA has (probably) failed to be passed on to the next generation.

Infant deaths account for the majority of them, but I don't know much about them.

The top causes of deaths among teenagers are accidents, suicide, and homicide. Certainly there is a genetic component to depression and subsequent suicidal behavior. Many accidents are car accidents caused by drunken driving -- there is probably a genetic component of how much alcohol impairs one's ability to drive. I can only imagine outlandish scenarios where one's genes affect whether one will survive or avoid a homicide attempt. Even if we did evolve to survive handgun gunshot wounds, technology would probably keep pace to develop more deadly weapons.

Certainly the causes of teenage deaths paint an interesting prediction of future human evolution.

HIV may be transmitted through birth and breast feeding, and so AIDS might be (I don't know) a leading cause of death before the child grows up. Also even an uninfected child is less likely to survive if both parents die from AIDS. Sub-Saharan Africa might be evolving HIV-resistant people.

Or the AIDS virus might evolve to remain dormant in children until after puberty.

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