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How Neanderthal DNA Helps Humanity

quantamagazine.org

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Re: How Neanderthal DNA Helps Humanity

#11

Post by mikeash »

grondilu wrote: post #7
tokenadult wrote: post #2

The article is very interesting and informative, and comes from a good source. But I have to quibble about describing Denisovan and Neandertal hominins who were ancestors of current human beings as coming from a "different species," because by one of the main concepts of speciation, if two organisms can mate and have viable offspring, and then the offspring can further reproduce, you say the two organisms are part of…

That conception of what a species is has been my understanding as well for a long time. It's a very simple and clear concept but apparently biologists have given up on it for various reasons. There's actually a whole wikipedia article about it: https://en.wikipedia.org/wiki/Species_problem

That's because the ability to mate and have viable offspring is not anything like a simple and clear concept in some cases. For example: https://en.m.wikipedia.org/wiki/Ring_species

Re: How Neanderthal DNA Helps Humanity

#12

Post by Ericson2314 »

agumonkey wrote: post #9
danieltillett wrote: post #6

Earlier quoted context omitted.

The 99% is basically wrong. What it is referring to is that for 99% of genes you can find in humans you can find an ortholog in chimps. It tells you nothing about the function of the genes in the two species and is basically meaningless from a functional perspective.

Does this means that if there are 3 genes a,b,c in mammal 1 and a,b in mammal 2, the lack of c can lead to a significant difference in the role/interpretation/function of a and b ?

I think so. That + epigenetics, and the "one gene one protein" slogan one learns in grade school aggregiously plays down the complexity, even if it's not false per se.

Re: How Neanderthal DNA Helps Humanity

#13

Post by agumonkey »

Ericson2314 wrote: post #12
agumonkey wrote: post #9

Earlier quoted context omitted.

Does this means that if there are 3 genes a,b,c in mammal 1 and a,b in mammal 2, the lack of c can lead to a significant difference in the role/interpretation/function of a and b ?

I think so. That + epigenetics, and the "one gene one protein" slogan one learns in grade school aggregiously plays down the complexity, even if it's not false per se.

I didn't study biology so my 'knowledge' is limited to the approximations fed before. But as a programmer, I can imagine that a change at lower layers can impacts upper layers tremendously. I'd like to read more about gene interrelation / dynamics.

Re: How Neanderthal DNA Helps Humanity

#14

Post by danieltillett »

Ericson2314 wrote: post #10
danieltillett wrote: post #6

Earlier quoted context omitted.

The 99% is basically wrong. What it is referring to is that for 99% of genes you can find in humans you can find an ortholog in chimps. It tells you nothing about the function of the genes in the two species and is basically meaningless from a functional perspective.

I'm no geneticist, but isn't this "structural" number still valuable for other purposes? Also isn't the 6pp also "structural" so modulo my previous complaints we're comparing like measurements?

Yes it can help you work out how related two species are to each other, but as a means of knowing what an individual gene does in each species it can be highly misleading. Ask any pharmaceutical researcher how much the concept that sharing a gene means sharing a function can lead you astray.

Re: How Neanderthal DNA Helps Humanity

#15

Post by arcticfox »

Ericson2314 wrote: post #10
danieltillett wrote: post #6

Earlier quoted context omitted.

The 99% is basically wrong. What it is referring to is that for 99% of genes you can find in humans you can find an ortholog in chimps. It tells you nothing about the function of the genes in the two species and is basically meaningless from a functional perspective.

I'm no geneticist, but isn't this "structural" number still valuable for other purposes? Also isn't the 6pp also "structural" so modulo my previous complaints we're comparing like measurements?

Out of curiosity, how do you take the modulo of an (English) argument?

Re: How Neanderthal DNA Helps Humanity

#16

Post by jrapdx3 »

Based on prior discussions I've had the impression that the BNC2 and other skin-related Neanderthal genes were associated with less melanin pigmentation.

Melanin reduces penetration of UVB into skin cells, important in an equatorial environment to protect skin integrity. However in northerly latitudes, heavily pigmented skin is a disadvantage due to the role of UVB exposure in producing vitamin D, essential to survival.

Indeed the most pigmented skin requires 5 times the UVB exposure to produce equivalent amount of vitamin D vs. least pigmented. A possible tradeoff for adaptating to an environment with less available sunlight is greater susceptibility to developing conditions like melanoma, but that's admittedly an oversimplification of a very complex subject.

Re: How Neanderthal DNA Helps Humanity

#17

Post by rcthompson »

agumonkey wrote: post #9
danieltillett wrote: post #6

Earlier quoted context omitted.

The 99% is basically wrong. What it is referring to is that for 99% of genes you can find in humans you can find an ortholog in chimps. It tells you nothing about the function of the genes in the two species and is basically meaningless from a functional perspective.

Does this means that if there are 3 genes a,b,c in mammal 1 and a,b in mammal 2, the lack of c can lead to a significant difference in the role/interpretation/function of a and b ?

That's certainly a possibility, but you don't even need to get that complicated. Gene A in humans could have a slight difference in its DNA sequence that causes it do work differently from the chimpanzees' copy of the same gene.

Re: How Neanderthal DNA Helps Humanity

#18

Post by Steko »

grondilu wrote: post #7
tokenadult wrote: post #2

The article is very interesting and informative, and comes from a good source. But I have to quibble about describing Denisovan and Neandertal hominins who were ancestors of current human beings as coming from a "different species," because by one of the main concepts of speciation, if two organisms can mate and have viable offspring, and then the offspring can further reproduce, you say the two organisms are part of…

That conception of what a species is has been my understanding as well for a long time. It's a very simple and clear concept but apparently biologists have given up on it for various reasons. There's actually a whole wikipedia article about it: https://en.wikipedia.org/wiki/Species_problem

Nothing in your link suggests they've all given up on the concept.

Re: How Neanderthal DNA Helps Humanity

#19

Post by danieltillett »

rcthompson wrote: post #17
agumonkey wrote: post #9

Earlier quoted context omitted.

Does this means that if there are 3 genes a,b,c in mammal 1 and a,b in mammal 2, the lack of c can lead to a significant difference in the role/interpretation/function of a and b ?

That's certainly a possibility, but you don't even need to get that complicated. Gene A in humans could have a slight difference in its DNA sequence that causes it do work differently from the chimpanzees' copy of the same gene.

It gets even more complicated than this - the gene could be identical in sequence and still have a different function because of a change somewhere else in the genome. The genome is the ultimate spaghetti code that is the result of 3.5 billions years of hacks upon hacks upon hacks.

Re: How Neanderthal DNA Helps Humanity

#20

Post by riffraff »

danieltillett wrote: post #3

The world map for Denosovian DNA is wrong. The Australian/Papua population is around 6% not the 0.8% which the figure shows. It is a shame that Africa is so ignored in these studies. We know that there were many interbreeding events that occurred in Africa (the African pygmies are one example), but we know almost nothing more.

> the African pygmies are one example

can you expand on this?

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