The book The 10,000 Year Explosion claims that human evolution did not stop when modern humans appeared, and in fact is accelerating since the agricultural revolution. Peter Frost says in his latest article that our genetic evolution “accelerated more than a hundred-fold when hunting and gathering gave way to farming”. Is this true?
Firstly, we are primarily adapted to a hunter-gatherer lifestyle. We have more copies of amylase genes than Neanderthals or Denisovans. Amylase is an enzyme that helps digest carbohydrates. This suggests that we have been selected for better digestion of carbohydrates since we started eating them in bulk. However, the level of change is likely very small compared to the genes that have not changed (the meat-eating genes).
Refined carbohydrates (including sugars) are the main reason our modern diet is failing us. People are jumping on the keto or carnivore bandwagon with amazing results. So we have evolved only slightly to digest carbs better.
There are many examples of modern humans retaining a hunter-gatherer brain. Why are we so group oriented? Because teamwork is much more important for hunter-gatherers than for farmers. Why do women prefer muscular men? Why are people in rural areas happier than those in cities? Why do we play sport? Why are people in farming societies shorter?
Secondly, while we have maintained our HG brain, we are still evolving. But is it accelerating? To answer, lets look at the requirements of evolution. Evolution is descent, with mutation, acted on by selection.
Do we have descent? Yes.
Do we have mutation? Yes, lots. Many more people = many more mutations.
Do we have selection? Sort of.
Accelerated selection would require polygamy or infant mortality at higher rates than we had during our hunter-gatherer epoch. The other option is population bottlenecks. This wasn’t really the case, with some exceptions.
The obvious exception is the systematic execution of criminals in Europe from 1000AD - 1800AD. The Church and the State came to a consensus founded on the belief that the wicked must be punished for the good to live in peace. Each generation there was up to 1% of all men being condemned to death. This pacified us, and increased our intelligence.
We also could have been selected for immune health. Agriculture eliminated the need for humans to be mobile, allowing much larger groups. This proximity may have led to greater opportunities for infectious diseases to spread. Consequently, more people were exposed to, and died from, diseases.
The Malthusian explosion (increasing population until we reached food-bearing capacity) after the agricultural revolution led to more frequent large-scale battles. Did that affect our evolution? Possibly, its hard to say.
In the modern era, selection pressures are not obvious. Infant mortality has plummeted, and around 75% of people have 1-3 kids. A population bottleneck is nowhere in sight. We are becoming less intelligent by about 0.5-1 IQ point per decade, simply because more intelligent people don’t have that many kids.
In conclusion, are we still evolving? Yes, but its only been 10,000 years since the agricultural revolution, while the rest of our human timeline (2 million years) has been hunting and gathering. I’m not sure it is accelerating by a “hundred-fold”, but if it is, it still has a long way to go to replace our hunter-gatherer based genome. I am generally a bit skeptical of claims about group differences arising since the agricultural revolution.
It is far easier to assess past rates of evolution than present rates. Nevertheless, I believe that our selection pressures are certainly weaker than those experienced on the mammoth steppe during the glacial maximum.
References
Dutton, E., & Woodley of Menie, M. A. (2018). At Our Wits' End: Why We're Becoming Less Intelligent and What It Means for the Future (1st ed.). Imprint Academic (IPS).
Frost, P. (2023, April 27). How rice farming remade East Asians. Substack. www.aporiamagazine.com/p/how-rice-farming-remade-east-asians
Frost, P., & Harpending, H. C. (2015). Western Europe, State Formation, and Genetic Pacification. Evolutionary Psychology, 13(1). https://doi.org/10.1177/147470491501300114
Lennerz, B. S., Mey, J. T., Henn, O. H., & Ludwig, D. S. (2021). Behavioral Characteristics and Self-Reported Health Status among 2029 Adults Consuming a "Carnivore Diet". Current developments in nutrition, 5(12), nzab133. https://doi.org/10.1093/cdn/nzab133
Mareike C Janiak (2019) Evolution: Of starch and spit eLife 8:e47523. https://doi.org/10.7554/eLife.47523
Mummert, A., Esche, E., Robinson, J., & Armelagos, G. J. (2011). Stature and robusticity during the agricultural transition: evidence from the bioarchaeological record. Economics and human biology, 9(3), 284–301. https://doi.org/10.1016/j.ehb.2011.03.004
Sørensen J. F. L. (2021). The rural happiness paradox in developed countries. Social science research, 98, 102581. https://doi.org/10.1016/j.ssresearch.2021.102581
Interesting read. I also found interesting what you said about systematic execution in Europe during 1000AD -1800AD. I have been wondering what kind of pressures were acting upon the European populace during that time, and which pressures were most significant in developing exceptional intelligence. No doubt the rise of universities, industrialization, urbanization, and other pressures were relevant during that period. The effect of execution however, I did not consider closely. The practice is akin to eugenics, in the sense that genotypes not likely to bring forth genetic improvements are removed from the pool.