Posts Tagged ‘ancestry’

Genographics, Neanderthals and Cannibalism, an Interview with Carles Lalueza-Fox

// December 8th, 2010 // 1 Comment » // Recent Research, Science Communication, Sex and Reproduction

After the event last night about the worldwide Genographic Project, I caught up with Prof Dr Carles Lalueza‑Fox, the first speaker on the night, for a quick interview. He’s an expert on Neanderthals, or Neandertals I think we call them now. Named after the Neander Valley where the first specimen was discovered.

What first sparked your interest in studying Neandertals?

When the first Neandertal sequence was retrieved in 1997 I had been working on ancient DNA for a while, but then Neandertals seemed to be something in a different league.

In the first ten years it was only possible to get mitochondrial DNA from Neandertals.

For me, I really liked Neandertals and human evolution as a child. Ancient DNA was something particularly difficult at the time, and the thing that brought me to the subject.

How human do you think Neandertals were?

How human?

Yes, tricky question.

Haha, yes. It’s a very long question, a very difficult question. One must always take into mind our tendencies are always fluctuating. We saw them as a very primitive human lineage in the early 20th Century, but I’d say that now we’re turning to the point where we see them as very similar to us.

Maybe the best thing to think about Neandertals is they are more different from us than any modern human to any other modern human. That’s the way we should think about them.

If we want to think of them as a different species that’s fine for me, but there is a range of difference between us and the Neandertals.

The cuts found along Neandertal bones you suggest are evidence for cannibalism. Could they just be an example of de-fleshing prior to burial?

Well, yeah, it might be right in some circumstances. But this is not only cutting, you know de-fleshing the bones. It’s also fragmenting the bones with small stone tools, very small fragments, and even the skull, and the faces. For me it’s very difficult to think that this kind of post mortem activity is something more because this is a complete destruction of the bones.

It’s very similar to what we see in other sites with fauna, the bones are broken to extract the marrow in the same way.

And it’s a pretty common thing, well, not common these days, but certainly we humans have our own history of cannibalism.

Yes, well there are several sites with the signs in Neandertals. But you almost think that life was very tough and they were structured in very small groups, so the fact that you find another one… I mean you’d say “hey, we are Neandertals all of us,” but I’d say that’s a modern conception.

Whereas for them it might be “hey, you’re not one of my family I may as well eat you.”

Yeah, the idea of humankind, in fact, is very recent. After the second World War, and the UNESCO thing. So even the idea of humankind is more recent than we might think now.

And what do you think of the possibility of Neandertals and humans mating?

I think it’s plausible with the data we have. It was probably something that was a minority, restricted in time and space, it was nothing important in my view. The thing is we can detect it now in non-African modern humans is because this was an expanding population, so even a small event of just a few, say it was, this was amplified later on.

Science that’s only skin deep

// December 3rd, 2010 // 2 Comments » // How Things Work, Recent Research, Science Communication, Sex and Reproduction

I’m a guest blogger for the RiAus, and this post also appeared on their fancy website. To tell the truth, I really wanted to call this post “Hormonally Yours” in homage to the Shakespeare Sisters (anyone?) but I’ll save it for another post.

Recently I was in Arnhem Land, visiting some Indigenous communities with a couple of friends. While I was there, I got pretty jealous of everybody’s darker skin. “It’s so well suited for Australia,” one of my friends lamented. “I should be in Norway or something.”

Pale skin like mine is not great for Australia. I tan pretty easily, but only after being burned bright red. While I was in the NT I slathered sunscreen religiously, but still managed to get a highly embarrassing burn on my lower back when I was building a sandcastle (an epic sand turtle, actually. Totally worth it.)

Anyway, enough about me and my weirdly tanned lower back (it’s been months! Why won’t it go away?) Let’s talk about Nina Jablonski, an anthropologist. In 2000 she suggested a new reason why skin colour varies so much. It’s not an adaptation to protect against skin cancer and sunburn, like I always thought it was.

It’s real job is to keep us highly fertile by maintaining a delicate balance between two key vitamins: Vitamin D and Folic acid.

Pica's skin tone matched her UVB exposure like her scarf matched her dress. Image by Monja Con Patines

Vitamin D is obtained through some foods, but mostly from drinking in sunshine. UV light turns cholesterol into Vitamin D, which then goes to either your liver or kidneys to be converted to an active form.

Once active it helps white blood cells like macrophages kill bacteria, and helps control levels of calcium and phosphate – important for building healthy bones.

Deficiency in Vitamin D causes rickets, a disease resulting in soft, easily broken bones and deformity which can lead to early death.

So getting enough UV (specifically UVB light) is important to not dying, and therefore having reproductive success later in life. It’s been backed up by Yuen, A. (Vitamin D: In the evolution of human skin colour DOI: 10.1016/j.mehy.2009.08.007)

Natural selection favours soaking up UV.

Penny stayed under foliage at noon to protect her folic acid. Image by Monja Con Patines

Folic acid is obtained in leafy vegetables and fortified cereals. Rather than being made by UV, the light can destroy folic acid by literally breaking it apart. (Jablonski, N. The evolution of human skin coloration DOI: 10.1006/jhev.2000.0403)

Critical for DNA synthesis, folic acid is essential during pregnancy when a lot of new cells are being made.

Folic acid prevents against 70% of neural tube defects in embryos. Its destruction by UV is bad news.

Natural selection favours avoiding UV.

So there’s an ideal amount of UV light that needs to get through the skin – enough to produce Vitamin D, but not too much to destroy all the folic acid. Getting the balance right for the environment you’re in means higher fertility, which drives natural selection

This is what Nina Jablonski thinks caused the evolution of skin colour through the sepia spectrum we see today. Dark skin, with high melanin, stops more UV light. That’s exactly what you want if you live in a place with a lot of sun, like places near the equator. Light skin lets more UV in, which is great if you live somewhere overcast and not very high on UV.

Understanding how your skin colour (NOT your race) influences these two vitamins is important in being healthy. It’s more important now than ever, because we humans travel a LOT.

Sadly, Australia is pretty high in UV and I am pretty white. Thank god for sunscreen.

Things are rarely that simple though, and I imagine there’s a few different things going on that connect UV light to skin colour.

On Tuesday the RiAus is holding an event called Skin Deep: Exploring human ancestry. They’ll be showing a preview of a new SBS documentary about skin colour scientific research, as well as results from the Genographic Project. Basically they took DNA samples from a lot of volunteers and some national identities, and now they’re giving us the goss on who’s related to who’s secret love child.

I’ll be there, I’d love to see you (though seats are limited.) I’ll be the one tweeting in the corner. Follow me @CaptainSkellett

Would love to hear from anyone who took part in the Genographic Project, and anyone who didn’t. Who would you most like to be related to? For me it’s David Attenborough, then I can dream of inheriting his voice.






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