May 18th, 2006



Nature: Chimpanzee and human ancestors may have interbred

The evolutionary split between humans and our nearest evolutionary cousins, chimpanzees, may have occurred more recently than we thought, according to a new comparison of the respective genetic sequences. What's more, it might have been a messy divorce rather than a clean break — leading to the controversial theory that our two sets of ancestors may have interbred many thousands of years after first parting company.

The discovery also casts doubt on the status of fossils that were thought to represent the first flowering of the human branch of the evolutionary tree — but which now may have to be reclassified as coming from a time before our split with the rest of the apes.

Nature, May 2006
Genetic evidence for complex speciation of humans and chimpanzees
FIGURE 1. Genetic relationships

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"For the first time we're able to see the details written out in the DNA," said Eric Lander, one of the collaborators on the study. "What they tell us at the least is that the human-chimp speciation was very unusual."

Unusual, indeed. The researchers, from the Broad Institute of MIT and Harvard, propose that humans and chimpanzees first split up about 10 million years ago. Then, after evolving in different directions for about 4 million years, they got back together for a brief fling that produced a third, hybrid population with characteristics of both lines.

That genetic collaboration then gave rise to two separate branches -- one leading to humans and the other to chimps.

DNA Study Maps Human-Chimp Split
NewScientist: Tangled Family Tree

На мой взгляд, это лишь демонстрирует полную чехарду с перенесением молекулярных древес на реальную филогению.


Professor Andy Clark: 'Extended Mind' paradigm

...we almost have the idea that there’s a "little us" inside of ourselves animating all the rest. So we can say something like you know, "well it’s my brain, it’s my hippocampus, it’s my arm" but of course there’s a clear sense in which you just are that mass of stuff. You know you don’t own your hippocampus, your hippocampus is just part of you.

And I guess the claim I’m trying to make is that when we co-evolve with our technologies in certain ways that’s the way that we should think of the relation between us and our technologies. Just like me and my hippocampus. It’s very, very hard to get rid of the idea of a wafer thin self that somehow is where the real action is, the final decider, the final chooser, but you go looking for that you in the brain and you can’t find it.

...I’m sure that being brought up with pen and paper typically in front of you when you’re trying to do philosophy for example is a completely different experience as a philosopher than being brought up in an oral tradition to do philosophy. And I bet that the biological brain as good and as lazy as it is just learns to factor that stuff in so that it’s kind of like half of the problem solving system. It sort of learns to lean on those properties of the environment, to expect them to be there.

...And I kind of think of the biological brain as something like the boot program of human intelligence, it kind of gets the thing going but it’s job is to pull in all this other structure, to load up all this other stuff and that’s when we really become fully human.

Natural Born Cyborgs: Minds, Technologies, and the Future of Human Intelligence
Andy Clark interviewed on ABC Radio National (2003) Transcript

Dynamicist Cognitive Science links

Хочу выразить искреннюю благодарность unokai за наводку на материалы. Выражаю.


Human genome completed (again)


Around half the genes in the human genome still have no known function, so researchers are trying to figure out what they do, and to reveal more details about how one person's genome differs from another. Scientists are also increasingly scrutinizing the regions outside genes, which were once discounted as junk but are now thought to harbour all kinds of useful sequences.

Nature, May 2006
The DNA sequence and biological annotation of human chromosome 1

см. также

(no subject)

Старенькая заметка Гоулда...- а все равно актуальная.

We are prisoners of the perceptions of our size, and rarely recognize how different the world must appear to small animals. Since our relative surface area is so small at our large size, we are ruled by gravitational forces acting upon our weight. But gravity is negligible to very small animals with high surface to volume ratios; they live in a world dominated by surface forces and judge the pleasures and dangers of their surroundings in ways foreign to our experience.

Steven Jay Gould, Size and Shape: The immutable laws of design set limits on all organisms