How Neanderthal DNA Helps Humanity
quantamagazine.org
How Neanderthal DNA Helps Humanity
1–10 of 27 posts
Re: How Neanderthal DNA Helps Humanity
#2The 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 the SAME species. There are, of course, full-length books about the details of defining species among the common descendants of the earliest living things, and about the mechanisms that bring about speciation among the descendants of a common ancestor species,[1] but right now we don't always know for sure when we dig up old hominin bones which belong to relatives of direct ancestors of living human beings and which do not--that is part of what the studies of ancient DNA are intended to find out.
To make the point I am bringing up here, I would rewrite the second sentence of the helpful article kindly submitted here to read, "As the individuals who provided the main genetic contribution to modern humans began to spread out of Africa roughly 50,000 years ago, they encountered other hominin clades that looked remarkably like them — the Neanderthals and Denisovans, two groups of archaic humans that shared an ancestor with us roughly 600,000 years earlier."
[1] http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3D...
Re: How Neanderthal DNA Helps Humanity
#3The 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.
Re: How Neanderthal DNA Helps Humanity
#4The genome percentages in the article are a bit confusing. It is oft-quoted that we are "99% Chimpanzee", so how could we also be no more than "6% Denisovan"? Answer: they really mean 6 percentage points "realigned" vs the African reference populations. I've read many other articles repeating the "6%" and it would be nice if they (and this) were clearer (and used the correct units--but maybe that's too much to ask).
Some cool charts for reference: http://www.scientificamerican.com/article/tiny-genetic-diffe...
Re: How Neanderthal DNA Helps Humanity
#5The 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…
Lions and tigers can mate and have fertile offspring yet no one would consider them the same species [1]. Actually there is evidence that the offspring of ancient African and Neanderthal matings [2] followed Haldan's rule [3].
If this discussion was about anything other than humans there would be no question that Ancient Africans, Neanderthals and Denosovians were anything other than different species.
1. https://en.m.wikipedia.org/wiki/Liger
Re: How Neanderthal DNA Helps Humanity
#6The genome percentages in the article are a bit confusing. It is oft-quoted that we are "99% Chimpanzee", so how could we also be no more than "6% Denisovan"? Answer: they really mean 6 percentage points "realigned" vs the African reference populations. I've read many other articles repeating the "6%" and it would be nice if they (and this) were clearer (and used the correct units--but maybe that's too much to ask).…
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.
Re: How Neanderthal DNA Helps Humanity
#7The 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:
Re: How Neanderthal DNA Helps Humanity
#8The 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…
"If two organisms can mate and have viable offspring, and then the offspring can further reproduce, you say the two organisms are part of the SAME species."
Firstly, that's not true.
Even if that were true, there is no evidence of reproductive success between human males and Neanderthal females.
Re: How Neanderthal DNA Helps Humanity
#9The genome percentages in the article are a bit confusing. It is oft-quoted that we are "99% Chimpanzee", so how could we also be no more than "6% Denisovan"? Answer: they really mean 6 percentage points "realigned" vs the African reference populations. I've read many other articles repeating the "6%" and it would be nice if they (and this) were clearer (and used the correct units--but maybe that's too much to ask).…
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 ?
Re: How Neanderthal DNA Helps Humanity
#10The genome percentages in the article are a bit confusing. It is oft-quoted that we are "99% Chimpanzee", so how could we also be no more than "6% Denisovan"? Answer: they really mean 6 percentage points "realigned" vs the African reference populations. I've read many other articles repeating the "6%" and it would be nice if they (and this) were clearer (and used the correct units--but maybe that's too much to ask).…
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?