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Physicist, Startup Founder, Blogger, Dad

Saturday, June 01, 2013

The genetics of humanness




Roughly speaking, modern humans differ from chimpanzees with probability 0.01 at a particular base in the genome, from neanderthals with probability 0.003, and from each other with probability 0.001 (this final number varies by about 15% depending on ancestral population). The neanderthal research is particularly interesting in that we will eventually be able to determine the specific genetic changes that make modern humans different (smarter?) than neanderthals. Certain regions in the genome, known as HARs (Human Accelerated Regions) are conserved in mammals such as mice, dogs, chimpanzees, even neanderthals, but show rapid recent changes in humans. It's reasonable to suspect that these regions are doing interesting things ...

See also this recent paper: Analysis of Human Accelerated DNA Regions Using Archaic Hominin Genomes (PLoS).

10 comments:

Mulcaster said...

"...make modern humans different (smarter?) than neanderthals."

Again with this bs. I guess Steve is just incapable of understanding some things. The meaning of "smarter" is a context dependent. So much so that different words should be used.

For example:

1. "UHB (see Metropolitan for meaning of UHB) A is smarter than UHB B."

2. "This UHB is smarter than this Arnhem Land Abo."

3. "This human is smarter than this Neanderthal."

1, 2, and 3 all use "smarter" in very different senses. GET IT?

Robert Sykes said...

And most our DNA is simular to that of bacteria because our metabolism is essentially the same and we use the same building blocks to make cells. I was unable to find the percentage similarity with bacteria, but for fish it is about 75%. The basic fact is that differences among species depend not on differences in DNA that codes for protein but on the bits of DNA that control the rest. People talk about junk DNA that doesn't code for protein, but this is just stupidity. The last couple of decades has shown that some of the junk actually is a control system, like microDNA.



By the way, why are the neanderthals and denosovians (H. erectus?) separate species from H. sapiens? They certainly meet the Dobzhansky/Mayer criterion for being the same species.

Simon Waters said...

Isn't there a Youtube video by a chap who studied Apes who said yes these gene difference will code for interesting things; short hair, differences between hands and feet, walking upright. He seemed to be of the view the primary physical difference relevant to intelligence was probably size of brain, and that this might not account for much genetic difference at all. Darn, can't remember the chaps name, just that he was ape expert at US university and bearded....

steve hsu said...

Neanderthal brains were similar in size to human brains. (Perhaps even bigger?) Whatever makes us smarter is in the small differences between us and them ...

Simon Waters said...

Neanderthal brains were bigger - at least we show signs of domestication including smaller brains compared to earlier homonids (I believe that was the neanderthals - there are ever more homonid distinctions being made it might have been refined (or corrected) since I read it).

You are presuming we are smarter than Neanderthals - I've had that discussion in comments on an earlier blog post here. Suffice to say there is evidence that Neanderthals made tools and played musical instruments, to a first approximation I'm going to assume they were of the same order of intelligence as modern humans till better evidence arrives, since most of the people I know don't make their own tools, and I can't play a musical instrument.

This looks like the right video.....
http://www.youtube.com/watch?v=AzDLkPFjev4

Simon Waters said...

Omo remains ~195,000 - we've had 200K years and done not much till that last 9K, at least I'm not aware of much evidence from before the early middle eastern civilization - who cultivated self fertile figs.

Yes there is a good chance of a difference but it needs more to back it up. If we'd been wiped out by Flores man 10K+ year ago, they might be here discussing how little homo-sapiens have to show for 200K years.

Entirely possible it is the domestication that made society possible, because pyramids and stone circles didn't get built without societies to back them. A Star Trek episode I must have missed - how on earth did Klingons build spaceships when they can't so much as cough without someone being killed, or wounded. I'm intensely interested in why suddenly we started cultivating food and building cities, but not sure genetics holds the key, and if it does it seems likely it is mutations later than the original emergence of homo-sapiens. The domestication also involved changes to jaw, and possibly we've become more vocal. The genetics will answer it eventually as we have neanderthal DNA.

steve hsu said...

> I'm intensely interested in why suddenly we started cultivating food and building cities, but not sure genetics holds the key, and if it does it seems likely it is mutations later than the original emergence of homo-sapiens. <


Yes, it's the *later* version of homo sapiens that we are genotyping. So those mutations you refer to are part of what makes us different.

Simon Waters said...

I have wondered if what has to change in intelligence is not necessarily the median ;)

We know a lot of our recent progress in science is explained by the "brilliance" of relatively few individuals. Okay we like the simple story of Einstein, and so Lorentz, Michelson, Morley, Poincare and many other "giants" tend to be in his shadow somewhat. But at the end of the day they are all pretty unusual as regards intellect.

Although I'm good at IQ tests, I'm best at "aping" (not that I don't have original thoughts but all the best ones I've had have been thought of before). So if I see a good idea, I can copy it and adapt it, apes can do that. Some monkeys can do that. Dogs can do it a bit. So we may not even need an increase in median intelligence if mutations gave us more geniuses, even simply an increase in variance might be sufficient assuming the extra stupids don't slow the extra clevers down too much.

But these ideas all come back to culture. To building schools, to valuing learning, to be willing to try new things, and I can quite believe that a few ideas like that coming together might be enough to change the course of history without much in the way of genetic change. Much of our recent progress must be cultural in nature, since it has extended to genetically distinct (and presumably thus not closely related) peoples exploited^W civilized by the British and other European empires. e.g. Genes don't explain the spread of electricity, or water sanitation, or the civil structures that make modern life possible. I'm not so sure about merchant banking as they all seem to be related to each other ;).

Certainly modern humans are equally capable of making a living hunting pigs in rain forest with spears, as dealing in derivatives, so we need to be careful of assuming other types of humans who hunted pigs with spears were innately less clever than modern humans, when we know culture can explain that large a variation within our own type of human.

gide07 said...

"...there are differences in average cognitive ability between us and them..."


I gave my dog an old SAT yesterday. He didn't answer a single question. My dog is so dumb.


I also took my pet dolphin for a walk in the park. He is so slow.

gide07 said...

From what I've seen the Neanderthals had smaller brains than some contemporary human populations.

Given that Neanderthals lived in an area coterminous with so-called "Caucasians", the possibility (or certainty?) of Neanderthal human interbreeding supports National Socialist ideology. That is, that Europeans are "special", the herrenvolk.

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