Saturday, April 2, 2011
New Thinking on our Old Ancestors
Some new articles have come across my desk in the last couple of weeks.
There's a lot of rethinking of human evolution going on out there. Where it stops is anyone's guess but it's going to be a fun ride.
First, let's talk about our friend, the Neanderthal.
Both of my readers (my wife and my friend Jan in KC) know I'm a big fan of Neanderthal. It's not a coincidence that my first published story, A Capella, was about Neanderthals. I think they've been vastly underrated. I'm happy to be able to say as time goes on I've been proved right.
It's a small triumph but one gets what one can.
The latest damage to the image of Homo neanderthalensis as a stupid brute comes in the form of fire.
Fire is Homo sapiens' friend. We've had control fire for a long time-- between 230k and 1.3 million years depending on how you look at the evidence and how you define control. But our image of Neanderthals was that they might have had fire but didn't control it like we do.
The continuing question has been how humans managed to operate in cold environments without fire. There's a site in England, probably of Homo heidelbergenis, about 800,000 years ago. The evidence suggests that the inhabitants did not have control of fire. There's unequivocal evidence that humans (not Neanderthals) had control of fire about 230k years ago at Terra Amata on the French Riviera-- why they needed fire there is beyond me. However, there are very old sites in South Africa and Kenya suggesting control of fire as much as 1.4-1.5 million years ago.
Paola Villa at the University of Colorado and Wil Roebroeks of Leiden University wanted to determine the earliest continuous control of fire. They did this by analyzing a database of sites and the evidence at the sites of fire use. They discovered that Neanderthals had continuous use of fire starting about 400k years ago-- close to when they first evolved in Europe-- and considerably before the site at Terra Amata.
This is not to say that Neanderthals had control of fire prior to Homo sapiens but they were at least contemporary. These guys get smarter the more we look at them.
The other article that's interesting confirms a supposition Darwin had back in the day. Darwin suggested that the use of tools had influenced the evolution of the human hand.
Now, the human hand got its start from the human big toe. Once we started walking upright we developed the human foot with the big toe. It turns out that much of the blueprint for the hand and foot are shared so when we got a big toe we got a big thumb, opening the opportunity for the hand to come under selective pressure.
Anthropologists at the University of Kent knew that there were many differences in our hands as compared to the our relatives that contributed to our own manual dexterity from making stone tools to typing out this blog entry. They decided to investigate Darwin's hypothesis.
They did so by investigating how variation in hand size would have an effect on the efficience of building stone tools. They found that variation did have an effect-- showing the selective opportunity.
Finally, John Hawks works with the Neanderthal genome. He's been blogging about his results. One of the things he's discovered is that there is the same frequency of Neanderthal genes in Chinese and European populations but that the Neanderthal genes represented in the two populations are different. The current hypothesis is that there was some mixing between the African and Neanderthal populations in West Asia. The groups split and genetic drift caused different genes to get established in the different populations. (Article here.)