biology, evolution, Science, science news

Human evolution continues to get more complicated

A good, if slightly technical article in the Guardian today here, about the ever-contentious split between modern humans (Homo sapiens) and Neanderthals. The evidence for interbreeding between humans and Neanderthals added up quite convincingly after the initial surprise discovery, probably shortly after the “Out of Africa” migration around 75,000 years ago. This article reports on results from sequencing mitochondrial DNA, which is only transmitted through the female line, suggesting there was some interbreeding between 413,000-270,000 years ago, a staggeringly long time ago. This is way before the main migration out of Africa by modern humans, and not that long after the split between the Neanderthal and Homo sapiens lineages from their common ancestor around 500,000 years ago. It seems that there may have been smaller migrations before our species successfully established itself outside of Africa.

I’ve written about human evolution before here, which gives an overview of some of the more recent findings about our relationships with other hominids. This new finding really strikes me again how migration is a defining feature of our species; it may well have been so for other hominids too. Maybe this is why our ancient relationships are just as mixed up as our modern ones.

evolution, Miscellaneous, Science and society

Humans: born to…migrate?

Following on from that Nature feature on human migration I blogged about  a couple of weeks ago, is another interesting piece in Science provocatively titled: “Busting myths of origin.” It is, however, exactly as the title says: analysis of DNA and isotopes in bones and teeth is showing that most of the people of the world are the products of multiple migrations: there are no “pure” peoples of any kind, with the exception of a very few groups, notably the indigenous Australian Aborigines, who, largely through accidents of geography and circumstance, remained isolated from many other human groups for a relatively long time. Migration and mingling, it turns out, is the norm for our species.

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biology, evolution, Science

The eyes have it

There’s been a lot of study into how vertebrates colonised the land, conjuring up lovely visions of our fishy ancestors hauling themselves out onto the mud on stumpy proto-limbs, helped by exciting fossil finds like Tiktaalik. What hasn’t been studied so much is why. It seems obvious – whole new ecological niches to expand into, and a rich abundance of invertebrate life to eat…but how did the animals know this before they got there? Well it may have been because they had evolved eyes sophisticated enough to take a good look at the view… Continue reading

biology, evolution, Science, Science and society

The (evolutionary) roots of lethal human violence

How much of human violence is innate, and how much of it is shaped by our environments? Are we a uniquely violent species? These are questions philosophers and social scientists have tried to answer for centuries. Now researchers have done an evolutionary comparison – and conclude that the rate of lethal human violence is six times that of the average mammal…but about average for a great ape.

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biology, Developmental biology, evolution, Science

Meanings in a song: Australian finches tell their chicks about the world outside the egg

I had one of those “I never knew that,” moments reading a paper in Science magazine this week, but, given that the research in question managed to get published in one of the top journals in the field, neither did lots of other people. The “that” in question? That sounds can alter the development of a embryonic bird to enable it to adapt to the environment it can expect when it hatches. Continue reading

biology, evolution, Explainer

Ladies, your hips change shape with your age

I read a rather interesting paper recently looking at the development of the human female pelvis, from late fetal stages until late adulthood. (You can find the full text for free here). The paper describes itself as challenging the “obstetrical dilemma hypothesis”: this is the idea that there are conflicting demands on the human female pelvis: to efficiently walk on two legs, a narrow pelvis is better, but to have large-brained babies, and to give birth safely to them, a wide pelvis is better. What I also find interesting, however, is that it takes the subconscious assumption that a large, bony structure, such as the human pelvis, is relatively fixed in proportion once you reach adulthood: turns out that, for women at least, it’s not.

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