Modern humans evolved ~195,000 years ago in Africa. But the first appearance of our species didn’t mark the end of our evolution. Since then we’ve continued to change and adapt to our environment. And it’s still happening. A study from Harvard examined whether modern Americans were still being influenced by evolution. It turns out they were. Evolution was changing how long they being educated.
We can’t easily escape from Darwin.
And yet we still sort of are. The research found that there was an evolutionary trend to spend less time in education. However, there was a cultural trend to spend more. When culture and evolution fought, culture won. By miles. Evolution has been pushing Americans to spend about 1 week less in education each generation. But thanks to culture, kids still wind up spending an extra 2 years at school.
Evolution occurs because of a few simple facts. Animals reproduce with variation. As a result, some of them fare better than others. So they have more kids. And that better variation is passed on more times, eventually spreading throughout the population. This is often simplified as “survival of the fittest”. But this hides a key fact. It should really be “reproduction of the fittest”.
So whenever someone is trying to study evolution reproduction should always be front and centre. This is often where many studies go off the rails. Researchers can easily identify a potential benefit that could aid reproduction. However, they rarely follow through to test if it actually results in more babies. So it should come as no surprise that half the time these findings are overturned.
Studying reproduction is the key to understanding evolution. So that’s what this most recent study from Harvard did. It examined various parts of humanity that may be evolving. Things like BMI, the risk of schizophrenia, height, education, cholesterol risk, and more. These were then compared them to lifetime reproductive success of ~6,000 people born between 1931 and 1953. If evolution was at work the two should be linked.
Sure enough, reproductive success was linked with many of these features. Smaller, stouter, less educated people tended to do well in the baby department. However, reproductive success is only one aspect of evolution. Some of the variation responsible for these behaviours needs to be inheritable. Otherwise, won’t get a chance to spread through the population.
As such, data on how much genetics influences these “evolved” features was also obtained. This could then be compared to reproductive success to see if evolution was really at work.
Less Educated Americans
When the heritability of these traits was taken into account the appearance of evolution vanished in many cases. For example, small women had significantly more children than their taller counterparts. However, those extra babies wouldn’t be enough to spread their small genes around.
Of all the factors considered, only two turned out to be undergoing evolution. The first was speed women hit puberty. There was selection for them to mature slower. It’s easy to imagine this as an adaptation for quality over quantity. We don’t have 23 kids and hope a few survive these days. Instead, we just have a few and take good care of them. So there’s less pressure to have them sooner, and more pressure for them to be healthier. Being a bit bigger and more mature when you first have them could help with that. However, there’s no data to confirm this is the driving force behind this development. Additionally, this change is very small.
The other factor still evolving was how educated Americans were. Ultimately, there seems to have been selection for genes linked to spending less time in education. However, much like the age at which women matured this effect was very small. Thanks to evolution, each generation spent about 1 week less in education. A result that seems barely noteworthy. Particularly when compared with cultural changes over this period. New policies meant people wound up spending an extra 2 years in education over this time period.
This contradiction is way more interesting than the seemingly insignificant evolutionary changes to education. It turns out that – for at least 2 decades in the early twentieth century – culture and evolution were in opposition. And culture won that fight.
This study comes with a huge number of caveats. The observed evolution was small. Thanks to culture, it didn’t have too much of an impact. It may not be the case the education was specifically evolving. It could be other traits were being selected for. The amount someone was educated could be a side-effect of this. There’s also no telling how long this effect lasted. The survey only examined people born between 1931 – 1953.
Despite this, it shows a fascinating fact: evolution and culture can be in opposition. This has been something hypothesised about for a while, but this is one of the clearest examples ever. This raises so many extra questions. Where, when, and why else has it happened? Was evolution “unhappy” with our ancestors living in caves? Does culture always “win”.
Clearly, this opens the door for a whole lot more research. In the meantime, I’m just happy that we managed to fight Darwin’s law, yet we won.
Research reveals that evolution has been influencing people recently. It’s driven them to spend less time being educated. However, culture counteracted it
Beauchamp, J., 2016. Genetic evidence for natural selection in humans in the contemporary United States. PNAS, 113(28):7774-7779.
Courtiol, A., Tropf, F.C. and Mills, M.C., 2016. When genes and environment disagree: Making sense of trends in recent human evolution.Proceedings of the National Academy of Sciences, 113(28), pp.7693-7695.