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Science bytes

 
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E-boy



Joined: 10 Jul 2006
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Location: Virginia (Much barfiness)

PostPosted: Fri Jun 24, 2011 12:04 pm    Post subject: Science bytes Reply with quote

It was recently announced that persons of european or asian decent carry DNA from other hominid species (Specifically Denosovan, and Neanderthal). Initially it was stated they did not believe these genes served any adaptive or functional purpose.

It now looks as though this material does serve an adaptive purpose. Specifically a fair amount of the 2 to 6 % of non-HSS DNA found in humans today seems to be localized in the area of the genome associated with HLA's. This material would have served the purpose of equiping moderns migrating into europe and asia with a robust immune response to local pathogens, and a more varied repertoire, immunologically speaking, in general. About 50% of the HLA genes in europeans are Neanderthal in orgin. Up to 90% of the HLA genes in New Guineans are Denosovan in origin.

HLA genes can also influence what humans and other animals find attractive in a mate through giving off HCC's. In a nut shell, the more different the HCC's are from your own the more different the HLA scheme of the other individual is from yours. It's thought this is found attractive (in an unconscious sort of way) because offspring would have a much more varied set of HLA genes to draw on for Anti-body production.

So maybe, Moderns coming into Europe found Neanderthals kinda sexy.
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Sam



Joined: 09 Jul 2006
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PostPosted: Fri Jun 24, 2011 12:09 pm    Post subject: Reply with quote

You protohumans can have your better math scores, we're the master race because we didn't shag neanderthals and that makes us genetically superior

*has it pointed out to him that neanderthals had bigger craniums and likely more developed reasoning skills/intellectual capacity relative to early homo sapiens*

yes, well I, no .. no, the point is white people are better, stop that, stop talking
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LD!



Joined: 11 Nov 2006
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PostPosted: Fri Jun 24, 2011 1:41 pm    Post subject: Reply with quote

I thought the larger space was to make room for
a large nasal passage?
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Sojobo



Joined: 12 Jul 2006
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PostPosted: Fri Jun 24, 2011 2:39 pm    Post subject: "shuo Cao Cao, Cao Cao dao" Reply with quote

Sam wrote:
likely more developed reasoning skills/intellectual capacity
LD! wrote:
large nasal passage?

Correlation Coefficient of One, Baby

and you know what else they say. . .
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Samsally



Joined: 10 Jul 2006
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PostPosted: Fri Jun 24, 2011 2:42 pm    Post subject: Reply with quote

Haha, is anyone else reminded of Disney's Tarzan movie?

No?

Just me?

Oh well.
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mouse



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PostPosted: Fri Jun 24, 2011 7:22 pm    Post subject: Reply with quote

i thought the original homo sapiens, coming from central africa, were probably black, whereas neanderthals, living up north with the shorter days and all were more likely to be light-skinned, for the vitamin d and all?
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Darqcyde



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PostPosted: Fri Jun 24, 2011 8:37 pm    Post subject: Reply with quote

Sam wrote:
You protohumans can have your better math scores, we're the master race because we didn't shag neanderthals and that makes us genetically superior

*has it pointed out to him that neanderthals had bigger craniums and likely more developed reasoning skills/intellectual capacity relative to early homo sapiens*

yes, well I, no .. no, the point is white people are better, stop that, stop talking


bigger brains + same sized vaginas = more fetal deaths

I'm paraphrasing btw. It's just one of the theories out there why Neanderthals didn't "win"
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Michael



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PostPosted: Fri Jun 24, 2011 10:16 pm    Post subject: Reply with quote

Don't worry Darc, we're all well acquainted with the 'perverted ape theory'
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Thy Brilliance



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PostPosted: Fri Jun 24, 2011 10:16 pm    Post subject: Cold virus etc Reply with quote

Weren't the multiple plagues in Europe responsible for the "fine tuning" of antibodies in Europeans?

AKA, viruses that inserted their own genetic code in our system and modified human DNA etc.
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Michael



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PostPosted: Fri Jun 24, 2011 10:49 pm    Post subject: Reply with quote

that's hardly "responsible" behaviour
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Mr Gary



Joined: 30 Apr 2009
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PostPosted: Sat Jun 25, 2011 12:48 am    Post subject: Reply with quote

I only wish I'd been taught to 'insert' my genetic code more responsibly. It'd have saved me a bomb on ungents, creams and specifics.
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Mr Gary



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PostPosted: Sat Jun 25, 2011 12:50 am    Post subject: Re: Science bytes Reply with quote

E-boy wrote:
It was recently announced that persons of european or asian decent carry DNA from other hominid species (Specifically Denosovan, and Neanderthal). Initially it was stated they did not believe these genes served any adaptive or functional purpose.

It now looks as though this material does serve an adaptive purpose. Specifically a fair amount of the 2 to 6 % of non-HSS DNA found in humans today seems to be localized in the area of the genome associated with HLA's. This material would have served the purpose of equiping moderns migrating into europe and asia with a robust immune response to local pathogens, and a more varied repertoire, immunologically speaking, in general. About 50% of the HLA genes in europeans are Neanderthal in orgin. Up to 90% of the HLA genes in New Guineans are Denosovan in origin.

HLA genes can also influence what humans and other animals find attractive in a mate through giving off HCC's. In a nut shell, the more different the HCC's are from your own the more different the HLA scheme of the other individual is from yours. It's thought this is found attractive (in an unconscious sort of way) because offspring would have a much more varied set of HLA genes to draw on for Anti-body production.

So maybe, Moderns coming into Europe found Neanderthals kinda sexy.


Dan, just so as I can read this properly - I'm not as bright as I once was, and I never glowed that bright anyway - can you explain the acronyms for me?
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E-boy



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PostPosted: Sat Jun 25, 2011 12:55 am    Post subject: Re: Cold virus etc Reply with quote

Thy Brilliance wrote:
Weren't the multiple plagues in Europe responsible for the "fine tuning" of antibodies in Europeans?

AKA, viruses that inserted their own genetic code in our system and modified human DNA etc.


That was a later development. Early moderns in europe were not engaging in animal husbandry yet, and not living in densities sufficient for the crowd disease that results to manifest. Yes those things left their mark on our immune systems. But the early environment did as well. One of the recent research findings is that Native Americans immune systems, while lacking natural immunity to crowd diseases europeans had to get the hard way, were primed to deal with parasites which were their big worry in north america. That's the kind of environmental Immune system adaptation I'm referring to.

As for Neanderthal brains being larger, they were. Even with the extra nasal space in there. Early modern brains were larger than they are today as well. In both cases the skeletal system was substantially more robust and carried more muscle, and more muscle generally requires more brain to control it. That's probabably not the whole story, but at least some of the brain size differential is certainly due to the large differences in muscle mass.

It's a bit tricky to assign purpose or consequence to morphological differences found in skeletal remians. Sometimes things are different due to genetic drift and random happen stance, and sometimes there is adaptive value to the difference. In the case of HLA differences they're in a pretty good position to make judgements about adaptive value because HLA genes serve a reasonably well understood purpose. There's quite a bit of debate about the purpose, or if there is a real purpose to the skull morphology differences in neanderthals (particularly as regards some of the nasal structures). Post cranial anatomy (Neck down) is virtually identical to moderns excepting the robustness of it. They did have more pronounced thumbs and particularly robust toe bones, and cross sections of the leg bones seem to suggest they weren't any where near as mobile as we are (Modern leg bones tend to have a tear drop cross section that gets that way from regular use rather than developmentally. The same bones in cross section from neanderthal specimens are virtually round, suggesting they didn't do a whole lot of trekking).

As of right now Denosovans are only known from a single pinky bone and their classification as an entirely new species was done on the basis of DNA recovered from that bone.

It's highly likely that other modern human groups carry contributions from other hominids as well, they just haven't found the evidence yet.
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