Humans ARE Still Evolving - But In Ways That Might Surprise You

A sea of humans at a sporting match (Image: “orange and blue” by Rhett Maxwell'). Wikimedia Commons, CC BY-SA

Danielle Andrew 16 Nov 2016, 18:17

Some striking examples have been found like that both women and men are currently under selection for earlier age at first birth across a wide range of societies.

Other work has shown that women are under selection for later age at last birth in some pre-industrial groups, but a later age at menopause in some post-industrial populations.

The upshot is that in some groups the reproductive span seems to be getting longer for both women and men.

Yet other research has shown that women are under selection for increased height in at least one pre-industrial population and for decreased height in three post-industrial groups.

The trend to early maturing at smaller body sizes may be the consequence of the widespread decrease in juvenile mortality resulting from improvements to hygiene, public health and medical care.

An interesting study published this year on the bioRxiv preprint server by a team led by Yair Field from Stanford University has studied DNA stored on the UK10K Project for the signs of recent evolution among living British people.

Field’s team investigated the signals of selection spanning the last 2,000 years and found evidence for evolution in three important sets of genes.

First, there has been strong selection for lactase genes, or those associated with a person’s ability to digest milk and other dairy foods.

So, dairy tolerance has been on the rise over the last couple of thousand years in Britain, perhaps along with increasing levels of milk consumption.

The second set was with the so-called HLA genes, which play a role in the human immune system.

While the possible cause is less clear cut it might be due to increasing levels of infectious disease exposure from greater numbers of immigrants such as the Romans who occupied Britain around 2,000 years ago and many groups after them.

But most surprising of all was the finding that the genes for blonde hair and blue eyes have been under selection over the last two millenia.

In this case, it seems that sexual selection rather than natural selection has been driving an increase in the number of people carrying the genes for this combination.

In the UK at least, it seems that gentlemen really do prefer blondes, well at least for the last 2,000 years anyway.

Far from being esoteric, this kind of research shows how the decisions we make about how we live, what we eat and even who we marry can have long lasting impacts on our evolution.

While governments and policy makers usually only have their eyes set on short time horizons, we really ought to be thinking about the consequences our modern lifestyle and the profound changes we’re making to the planet might have on our evolution as well.

 

Darren Curnoe, Director of the Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), UNSW Australia

This article was originally published on The Conversation. Read the original article.

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