I think you’ve just confirmed what Sheldon said
“Species” are not very well defined. Paleontologists work from bones, naturalists work with dead specimens, geneticists work with DNA, and ecologists work with living communities. Each group has its own definition, and very often they are in conflict with the others.
Are you saying that Humans, Neanderthals, and Denisovans are different species despite interbreeding or are you just saying they are different races within the same species?
If you want to think about ‘race’ in the modern sense, all human ‘races’ are clumped together in the gaussian structure on the left. (Edit: see @Christy’s post below for a better word than ‘race’) That is similar to this figure:
All humans alive today are clumped together as you can see, where our genetic diversity is represented by the horizontal length connecting us. Compare that to the closest other group, the Neanderthals, and we can see several things. One is all humans alive today are far more genetically similar than any of us are to Neanderthals. Thus if you want to say ‘oh they’re just another race,’ you would be incorrect as everything that is classified as a ‘race’ is much more similar than us with even Neanderthals!
I love a good graphic! That’s great.
I imagine they skipped American First Nations and Pacific Islanders because they were obviously included in the wider diaspora of “Asians”?
Without reading the associated article, the uncharitable take would be that this is a bit of subtle ethnocentrism… but anyway, I’m getting too far afield to be on topic. But it’s interesting to note.
Not to be overly nitpicky, but we had long discussions and pertinent articles about race and genetics here just a few months ago, so it would be good if we all tried to use the term correctly. Race is a social construct, not an identification based on genetic or biological realities. What we are talking about here are “people groups” or “ethnic groups.” Those are the right terms for human populations united by common culture, language and kinship bonds. And there would have been multiple people groups within each geographic area.
That is a truly remarkable prospect.
I read that the genetic difference between members of different human populations is less than .1 percent of the homo sapiens genome. Do you know what the average difference is between Neanderthals and Denisovans and early Homo Sapiens?
I think this infographic was helpful for me in thinking about this, as I think generally speaking reveals about a 0.2%-.0.5% difference between us and Denosvians (though some spots of genome are greater than 6% different - albeit very minimal in extent/frequency and some spots are less than 0.2% dfiferent). Neanderthals aren’t on this infographic but it’s the best I found in the time I have as I didn’t know myself:
Perhaps a Biologist could weigh in @T_aquaticus @sfmatheson @glipsnort @Sy_Garte (feel free to edit more in)
This is newly posted and seems helpful:
From the graphic the Denisovans are no more distant from the Africans than is the far end of the Asian & European group.
But if they’re not different races/ethnicities (@Christy) then what are they? Different species? In which case can we classify Africans as a different species to Asian & European? The graphic would seem to support that.
Based on the evidence of interbreeding I am quite happy to accept that Africans, Neanderthals, and Denisovans are the same species as me.
They are all the human race or the Homo sapiens species. The smallest lines at the end do represent different people groups or ethnicities within larger geographic zones. Africans and Asians and Europeans are made up of groups of populations that form different people groups (All the little lines). Each ethnicity does not constitute a different “race.” Those people groups may be lumped together or split apart for social reasons in different racial categories to serve social agendas. The idea that Africans are a different “race” of humans than Europeans is a social construct. The Tutsis in Rwanda considered the Hutus a different race, even though they were both Africans. For years, Eastern Europeans and Jews were not considered white in America. Racial designations do not depend on genetic realities, they are social constructs.
The infograph shows that different populations of geographically isolated humans share some biological characteristics. But the fact that they have common ancestry is important. Africans have greater genetic diversity within their population because the common ancestors came from Africa. (As shown by the branches that start further back to the right) Genetic diversity decreases in Asians and Europeans (the branches start further to the left) because of migration patterns out of Africa.
I’m not sure that is what the graph is intending to communicate.
Are they though? Do they have to be the same species to be human like you? That is the real question, and one that I don’t think science can answer, at least not in a way that sheds light on theological questions about the image of God or immortal soul.
The graph is a little tricky to read, so let me aim to unpack it a bit. To begin, the vertical bars mean nothing- it is only the horizontal bars that are important. The greater their length, the greater number of substitutions per site. So let’s take go through a few parts of it. Let’s look at the homo sapien section first:
I’ve went ahead and marked three spots with stars, two at the top and one at the bottom. How different should one read first (1) and (2) to be? Well, you have to go back to their common ancestor to compare them as they were once related based upon where they connect. Or this point marked by the yellow star:
You need to measure how far away (1) is from the yellow star horizontally and then take that distance relative to the scale bar. It’s approximately equivalent to 0.0007 substitutions per site. Very similar! But how does (1) then compare to (2)? Well we need to figure out how far away (2) is from their common ancestor. You can do the same thing, adding up the horizontal distance from (2) to the yellow star which gives us 0.0013 substitutions per site. Nearly twice as much as the distance from (1) to the star. So how then should we think of the genetic difference between (1) and (2)? Well, we know that (1) is different from a common ancestor by 0.0007 per site and (2) is different from the same common ancestor by 0.0013 per site. The simplest way would just be to add them. This would not be perfect as they could get the same differences but due to the randomness and improbability of such, we can consider them mutually exclusive and add them. So (1) is different from (2) by 0.002 substitutions per site! So then how about we ask how different is the most genetically diverse group of humans (3) from say the tip of the branch that (1) is located on? Well (3) is 0.0045 substitutions per site away from the common ancestor of all homo sapiens (the yellow star) and then you can add any other branch lengths. The furthest point along the branch with (1) is 0.003 substitutions per site away from the yellow star. Thus all the genetic diversity of humans corresponds to about 0.0075 substitutions per site maximum (though in many cases can be less).
Now how about humans and Denosvians? Let’s look at the graph one more time:
How different is the Denosvian genome compared to the human genome? Let’s just compare points (1) and (2) on the graph. You first have to add all of the horizontal distance to their common ancestor (3). So we find that the distance between (1) and (3) is about 0.0135 substitutions per site and the distance between (2) and (3) is about 0.012 substitutions per site giving a total difference of humans and denosvians of about 0.025 substitutions per site.
Thus in total we can say that Denosvians and ancient humans have over three times the substitutions per site (and even higher comparing them to modern humans) than all humans do alive today.
Great summary.
The gene FOXP2 is of interest. Humans and chimps differ by two mutations in this gene, and there are known disease causing mutations in the human gene that cause cognitive disabilities. It is thought that the two mutations that differ between the human and chimp gene are of importance to human intelligence. We also find the same two mutations in the Neanderthal and Denisovan genomes.
I’m not sure what that means for any theological positions, but it is of interest to how intelligent these populations may have been.
I didn’t realize this had to do with cognition; thought it had to do with expression/language?
Can you link me to another study on cognition? Interesting. (I only have old BBC articles)
I think it is mainly tied to language and how the brain deals with language. I did find this reference:
Search PubMed (pubmed.gov) for ‘FoxP2 cognitive’ and you will find a smattering of articles. Here is a review article from 2009:
https://www.cell.com/cell/fulltext/S0092-8674(09)00570-4
That paper is about effects in mice when the human version of the gene is substituted for the mouse version. I think the main connection between FoxP2 and cognition in humans (separate from language and speech) is from studies on patients with mutations in the gene. In general, it is rare for FoxP2 to be linked to cognition and I don’t think that evidence is very strong.
But almost certain that it is not due ONLY to the FOXP2 gene.
(Sorry, missing “not” added)
Thanks for that paper in your sister publication. Really fascinating stuff. Correct me if I’m wrong, but the link to cognition seems to be enhanced connectivity. That certainly played a part in human brain evolution, but it is far from the end of the story. A whole suite of changes concurrently was taking place, and many more genes besides FoxP2 had to be involved. There is no “cognition gene” or “language gene,” any more than there is a “cancer gene.”
In the Discussion, the authors say, “Humans share innate vocalizations like grunts, cries, and screams with other animals, but in addition humans have an unmatched ability to learn vocalizations (Egnor and Hauser, 2004, Hammerschmidt and Fischer, 2008). The acquisition and extensions of neural circuits making voluntary control of vocalizations possible is thought to be a hallmark in the evolution of human speech (Jürgens, 2002, Krubitzer, 2007).”
I wonder how much the FoxP2 gene in songbirds differs from that of humans and mice. Do mockingbirds have a different version of it than other songbirds? I wonder if a humanized version of FoxP2 could be tried in birds, too? Just thinking out loud.
Not sure what you are trying to say here, but I would add that no scientist thinks that the two mutations in FOXP2 explain all of the differences between chimp and human intelligence. It’s just a possible piece of the puzzle.
Correct. FOXP2 is just one piece of the larger puzzle. The NOTCH gene family is also thought to play a role:
http://www.sciencemag.org/news/2018/05/trio-genes-supercharged-human-brain-evolution
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