August 09, 2008
Neanderthal Mitochondrial DNA Fully Sequenced
Our cells contain organelles called mitochondria which break down sugar to provide energy. Those organelles have their own small genome separate from the very large genome found in almost every cell nucleus (excepting red blood cells). A scientific team in Germany has now successfully sequenced the mitochondrial DNA of Neanderthals. Using that information these scientists have calculated that Neandertals and humans went their separate ways about 660,000 years ago.
A study reported in the August 8th issue of the journal Cell, a Cell Press publication, reveals the complete mitochondrial genome of a 38,000-year-old Neandertal. The findings open a window into the Neandertals' past and helps answer lingering questions about our relationship to them.
" For the first time, we've built a sequence from ancient DNA that is essentially without error," said Richard Green of Max-Planck Institute for Evolutionary Anthropology in Germany.
The mitochondrial DNA is only about 15,000 letters (a little less). So by itself it doesn't tell us much about the vast bulk of ways that humans and Neandertals differ. But that amount of information is enough to estimate how far the two species formed separate from each other.
Analysis of the new sequence confirms that the mitochondria of Neandertal's falls outside the variation found in humans today, offering no evidence of admixture between the two lineages although it remains a possibility. It also shows that the last common ancestor of Neandertals and humans lived about 660,000 years ago, give or take 140,000 years.
Here's the really interesting part: We might some day have a complete Neanderthal genome sequence.
Scientists eventually hope to sequence a full Neanderthal genome.
That information would open up the possibility of eventually bringing Neanderthals back to life. What do you think of doing this?
Suppose some billionaire bankrolled the cloning of a Neanderthal. On what basis should we decide whether to grant it human rights? Suppose it has an IQ in the lower range for humans (say 80). But suppose it was totally hostile to us and dangerous. Should it be granted full rights? Or a subset of rights?
The ability to create creatures that are closer to humans than existing primates will force us to come up with far more precise criteria for what should be granted rights. We already grant subsets of rights to children and even to some adults. People imprisoned or committed to mental hospitals do not have all rights. But a Neanderthal or perhaps a dog or pig or lion genetically engineered to have low human IQs would pose much more complicated questions about why we grant rights. Imagine a 100 IQ creature who we could know will try to kill us. Imagine a 90 IQ creature that will not try to kill us or try to rob or otherwise harm us. Do we grant full rights to the latter while keeping the smarter but more dangerous creature in a sort of zoo?
It seems Neanderthal traits (taken individually, not as a package) would fall within current human biodiversity. We already have human adults who have less cognitive ability that most mammals.
Why would a Neanderthal necessarily act in an excessively aggressive way?
You'll never convince me that Neanderthals are extinct. Surely Homo sapiens is not entirely responsible for the state of the world.
What if the Neanderthal actually had a HIGHER IQ? To assume they were less intelligent because they are extinct is simply an anthropocentric fetish and nothing more.
Harry Tuttledove wrote a series of short stories set in alternate history in which the Americas were populated by Homo Erectus instead of Native Americans. He addressed a lot of the questions ask in the parent.
Neanderthals also had a culture and a paleoecology that their genes fit into. One without the others means no Neanderthal. Their IQs had to be high, given their success as hunters of megafauna, but also narrowly focused on their niche.
The Neanderthal phenotype is extremely strong - the average male Neanderthal is at least as strong as the strongest human athletes and probably just as quick if not quicker. Imagine a Randy White or Demarcus Ware or a top MMA fighter. They lived in hunter-gatherer groups and many of their fossils show signs of extreme trauma due to hunting accidents and likely signs of internecine fighting. A majority of male deaths in such a society come from killing each other. On the other hand, they have to be great parents to raise children successfully in such a high-threat environment with such cold temperatures.
karlito could be right. Traits other than low IQ could have lead to neanderthal extinction. Low levels of agression, for example.
I suspect that humans even a couple thousand years ago were dumber than they are today. If historian Gregory Clark is correct then the forms of social organization and technology that rose before the industrial revolution probably helped guide human evolution. The return on investment for being smart rose and this allowed smarter higher fertility people (again, before the industrial revolution made food cheap) to out reproduce dumber people.
My guess is that Neanderthals didn't have the selective pressure on them to develop such high IQs. They couldn't achieve the specialization of labor or maintain that much property for enough time to make the brains needed for planning for property management and technology maintenance to pay off.
Hunting megafauna is not hard. Look at the big cats. They aren't as smart as humans.
Neanderthals redux? What would really happen given the actualities of today's society?
They'd make big bucks playing in the NFL.
Lots of TV advt money making insurance ads.
They'd LOVE Northern Canada & Siberia, the new real estate 'hot' spots.
Neanderthals should be cloned, on moral grounds. Say that we became extinct and were dug up by another species similar to us; you would think it would be moral to clone us and bring us back to life, wouldn't you? Of course you would. It's the same with the neanderthals, who had bigger brains. Why did they go instinct? Well, why does one group of Homo Sapiens send a man to the moon while another, much the same, faces being wiped out by the elements in some backwater place? Besides, I suspect that the higher intelligence levels (in terms of I.Q., if you accept that 20th century psychological measurement as measuring intelligence), exhibited by Europeans and Chinese comes from our Meanderthal blood. There was more such blood 2500 years ago at the flowering of civilization.