How Neanderthal DNA Helps Humanity • Hacker News Board

Re: How Neanderthal DNA Helps Humanity

#21

Post by grondilu » Sun, May 29, 2016, 9:37 AM UTC

Steko wrote: post #18

grondilu wrote: post #7

Earlier quoted context omitted.

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.

Not the concept itself, but the aforementioned simple and clear definition.

Re: How Neanderthal DNA Helps Humanity

#22

Post by danieltillett » Sun, May 29, 2016, 10:09 AM UTC

riffraff wrote: post #20

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?

Sure. Have a look at this post [1].

1. http://dienekes.blogspot.com.au/2016/02/archaic-introgressio...

Re: How Neanderthal DNA Helps Humanity

#23

Post by agumonkey » Sun, May 29, 2016, 11:22 AM UTC

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.

Different sequence but same gene ? what is a 'gene' then ? a position on the DNA thread ? a % of similarity ?

Re: How Neanderthal DNA Helps Humanity

#24

Post by JoeAltmaier » Sun, May 29, 2016, 12:22 PM UTC

The colored map is informative - color reflects percent of archaic genes inherited by modern populations. But the placement of the colored dots looks suspiciously like a heatmap. I know the data is sparse. But maybe there'd be a better way to represent it.

Re: How Neanderthal DNA Helps Humanity

#25

Post by rcthompson » Sun, May 29, 2016, 8:37 PM UTC

agumonkey wrote: post #23

rcthompson wrote: post #17

Earlier quoted context omitted.

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.

Different sequence but same gene ? what is a 'gene' then ? a position on the DNA thread ? a % of similarity ?

Let's put it in git terms. Humans and chimps are derived from a common ancestor, so you can imagine them as two diverging forks of the same codebase, with their common ancestor being the last commit that they both share. Since then, either or both could have performed any sequence of additions, deletions, edits, duplications, etc., including cutting large sections out of one file and pasting them into another. However, for chimps and humans, the fork was recent enough that the vast majority of lines of code have been untouched since the fork, so for the vast majority of lines of human code, you can identify the corresponding line of chimp code, and vice versa. So when we talk about "Gene A" in humans and "Gene A" in chimps, this is presuming that the region of the genome containing Gene A is relatively unchanged between the two species. However, as you and others have pointed out, just because the gene's sequence is identical or nearly identical in the two species doesn't guarantee that it performs the same function in the two species. You could make an analogy to modifying a global variable in a completely different file that drastically changes the behavior of a function, even though that function's source code is unchanged.

So roughly speaking, a gene is a region of DNA that operates as a functional unit. The most well well-understood function is encoding a protein product and regulating its production. And when we talk about the "same" gene in different species, we're using "same" informally to refer to the genes in the two species that are derived from the same gene in their common ancestor. Usually, but not always, these genes perform the same or similar functions in the two species. Unlike a function in computer code, however, the bounds of a gene are not well-defined, and can overlap other genes or be non-contiguous.

For more: https://en.wikipedia.org/wiki/Homology_%28biology%29#Sequenc...

Re: How Neanderthal DNA Helps Humanity

#26

Post by Ericson2314 » Mon, May 30, 2016, 2:35 AM UTC

arcticfox wrote: post #15

Ericson2314 wrote: post #10

Earlier quoted context omitted.

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?

https://en.m.wikipedia.org/wiki/Modulo_(jargon) in ignoring the differences I already pointed out ("my previous complaints") I am defining an equivalence relation.

Re: How Neanderthal DNA Helps Humanity

#27

Post by arcticfox » Mon, May 30, 2016, 8:13 PM UTC

Ericson2314 wrote: post #26

arcticfox wrote: post #15

Earlier quoted context omitted.

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

https://en.m.wikipedia.org/wiki/Modulo_(jargon) in ignoring the differences I already pointed out ("my previous complaints") I am defining an equivalence relation.

Cool, thanks