So, what did they find? A whole bunch of stuff. They tested for 870 human traits in total, categorised in terms of the physical, the medical, the neurological, the behavioural and so on.
They cross-referenced their findings from contemporary European genomes against historical genomes of homo sapiens, including those from pre-neolithic hunter gatherers, early neolithic hunter gatherers, and near eastern farmers from the dawn of civilisation.
The study is dense, and it certainly helps if you are a trained geneticist, or at the very least a medical student, to read it. I am neither, but I was formerly a health correspondent, so I was able to pick out a few interesting discoveries.
Firstly, as might have been expected from the varieties of human skin tone among Europeans, this was one of the factors most prone to genetic selection over recent human history. Effectively, those in the south of Europe selected for ability to tan, while those at northerly climes selected for fairer skin. This was largely already understood to have happened.
Similarly, there is a positive selection for height. Gals have liked a tall guy throughout history, apparently. And there is also positive selection for blond and lighter hair colours, which again we could have deduced from the fact that these hair colours primarily exist among European populations.
Likewise already suspected, but perhaps less widely known, is the fact that Europeans positively selected for a predisposition to schizophrenia. It’s not clear why this is, given that schizophrenia is a debilitating mental illness. Nevertheless, the research indicates some positive selection for it, as well as, oddly enough, a predisposition towards anorexia.
Perhaps not so suspected are minor but yet statistically significant positive selections for a range of things, including raw vegetable intake and heavy alcohol drinking. Then again, Europe has a growing vegetarian and vegan population, and also tends to top the charts for excessive alcohol consumption worldwide.
The most significant evolved traits in recent history relate primarily to facial characteristics – not only hair colour but also things like nose shape and upper lip size. If this makes our ancestors seem somewhat superficial, more concerned with physical appearance than other traits, that may simply be because they are easier to immediately identify.
But much less easy to identify traits also show significant positive selection in recent times. Intelligence and insomnia have both been positively selected for in Europe in recent human history (by which I mean the past few thousand years). This makes sense of course, since it helps to be smart, and someone who stays awake at night is the first to notice nighttime dangers, but more generally this actually indicates that evolved traits go much deeper than the skin.
There’s a lot more in this study, and no doubt it will prove extremely interesting to other researchers. It certainly raises some questions, not only about the traits we have inherited from the neolithic period or our early farming history, but about the traits which seem to be subject to positive selection up to the present day.
One suspects these results can likely be extrapolated to other global populations by replicating the extensive work that went into this study. Or rather, perhaps not these exact results, but rather similar sets of results, indicating similar ongoing evolution in slightly different ways among different global populations.
It would be nice therefore to see similar studies for other global populations, in order to understand the extent to which, for example, the positive selections for schizophrenia and anorexia predisposition are universal or to what extent they’re merely European.
But the bottom line is this: we sometimes assume that recent history is not enough time for humans to have evolved much more than some few superficial variations, like skin tone. However, as this study shows, such evolved variegation is much more than skin deep, and reaches into our very behaviour and psyches.