When I first studied evolution as a sophmore in college the final exam included an open-ended question about whether humans were still evolving. I cannot remember what I wrote—that was before I really understood how to think about evolution—but my answer was probably all muddled.

Recent genetic evidence has gotten us used to the idea that humans have undergone strong and rabid selection regimes over the past 10,000 years. But there is still much to adapt to

Infectious diseases have the potential to act as strong forces for genetic selection on the populations they affect. We find that an HIV infection similar to that currently affecting sub-Saharan Africa could not yet have caused more than a 3 per cent decrease in the proportion of individuals who progress quickly to disease. Such an infection is unlikely to cause major genetic change until 400 years have passed since HIV emergence. However, in very severely affected populations, there is a chance of observing such major genetic changes after another 50 years.

and (although using ‘adapt’ in the sense of ‘acclimatize’)

Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature TW, is surprisingly similar across diverse climates today. TW never exceeds 31 °C. Any exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7 °C, calling the habitability of some regions into question.

Both of these studies are speculative and theoretical but show that evolutionary biology should look forward just as soon as look backward.

• Cromer et al. How fast could HIV change gene frequencies in the human population? doi: 10.1098/rspb.2009.2073 Proc. R. Soc. B 7 July 2010 vol. 277 no. 1690 1981-1989
• Sherwood & Huber. An adaptability limit to climate change due to heat stress. doi: 10.1073/pnas.0913352107 PNAS May 25, 2010 vol. 107 no. 21 9552-9555

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