A new timeline for Neanderthal interbreeding with modern humans(news.berkeley.edu)
news.berkeley.edu
A new timeline for Neanderthal interbreeding with modern humans
https://news.berkeley.edu/2024/12/12/a-new-timeline-for-neanderthal-interbreeding-with-modern-humans/
59 comments
It should also be noted another paper also came out today with new ancient DNA from a modern human whose bones carbon dated to around 45kya. The data suggests the individual was only 80 generations from the Neanderthal interbreeding event suggesting it happened around 45-49 kya. The event may have happened over a few generations realistically but I think 7000 years is unlikely due to the rapid expansion of humans out of Africa (or to be more precise an extremely successful expansion of a population of modern humans whose signal is difficult to filter out) all sharing this same introgression signature.
The wikipedia article opens with
"Neanderthals (Homo neanderthalensis or H. sapiens neanderthalensis) are an extinct group of archaic humans (generally regarded as a distinct species, though some regard it as a subspecies of Homo sapiens) who lived in Eurasia until about 40,000 years ago" https://en.wikipedia.org/wiki/Neanderthal
If Neanderthals and Homo sapiens could interbreed and produce offspring that could reproduce, doesn't that clear up any confusion about them possibly being a distinct species?
"Neanderthals (Homo neanderthalensis or H. sapiens neanderthalensis) are an extinct group of archaic humans (generally regarded as a distinct species, though some regard it as a subspecies of Homo sapiens) who lived in Eurasia until about 40,000 years ago" https://en.wikipedia.org/wiki/Neanderthal
If Neanderthals and Homo sapiens could interbreed and produce offspring that could reproduce, doesn't that clear up any confusion about them possibly being a distinct species?
A species isn't defined by if it can interbreed with other species or not. Horses and donkeys can produce offspring (although they are mule - and there's some discussion about how certain Neanderthal/Sapiens combinations could possibly also be mule, but that's not important). And Darwin's finches (https://en.wikipedia.org/wiki/Darwin%27s_finches) are defined as different species, but can technically interbreed.
By calling them "H. sapiens neanderthalensis", the authors are tipping their hand. They view Neanderthal's as a subspecies. There are those who disagree. The definition of what a species is seems to depend on who you talk to.
There are examples of animals, currently classified as different species, being able to interbreed and produce fertile offspring.
e.g. Polar bears (Ursus Maritimus) and Grizzlies (Ursus arctos horribilis) can breed to produce fertile Grolar bears[1].
TL;DR: Although Polar bears and Grizzlies appear to be very different, they diverged relatively recently and have remained distinct mainly through geographic separation. They don't interbreed much because they generally aren't in the same places during mating season. Although their physical traits have changed considerably, genetic differences haven't yet built up to the point where their offspring are infertile.
It's conceivable that the different subspecies of humans were isolated from each other in very different environments and evolved along very different lines. However, they weren't isolated from each other so long that genetic changes made it impossible for them to produce fertile offspring.
[1]https://slate.com/news-and-politics/2010/05/when-polar-bears...
There are examples of animals, currently classified as different species, being able to interbreed and produce fertile offspring.
e.g. Polar bears (Ursus Maritimus) and Grizzlies (Ursus arctos horribilis) can breed to produce fertile Grolar bears[1].
TL;DR: Although Polar bears and Grizzlies appear to be very different, they diverged relatively recently and have remained distinct mainly through geographic separation. They don't interbreed much because they generally aren't in the same places during mating season. Although their physical traits have changed considerably, genetic differences haven't yet built up to the point where their offspring are infertile.
It's conceivable that the different subspecies of humans were isolated from each other in very different environments and evolved along very different lines. However, they weren't isolated from each other so long that genetic changes made it impossible for them to produce fertile offspring.
[1]https://slate.com/news-and-politics/2010/05/when-polar-bears...
It is more like a race.
There are people with Neanderthal heretige living today. It is even used as a slur.
There are people with Neanderthal heretige living today. It is even used as a slur.
The classic elementary school definition of species is something like “x and y are different species if they cannot produce fertile offspring” which is obviously already incomplete (it causes eg two males of one species to be different species, for example) but could be made a bit more precise.
But the actual definition is much more “a species is a group of reasonably closely related and similar organisms, capable of reproducing fertile offspring given sufficiently many individuals, and the grouping is useful for scientists to talk about”. Obviously that definition isn’t useful for a layperson to decide how to taxonomize things, but I think it’s a useful definition to have when reading about classifications of things into species.
But the actual definition is much more “a species is a group of reasonably closely related and similar organisms, capable of reproducing fertile offspring given sufficiently many individuals, and the grouping is useful for scientists to talk about”. Obviously that definition isn’t useful for a layperson to decide how to taxonomize things, but I think it’s a useful definition to have when reading about classifications of things into species.
also see “ring species”. there are types of co-habiting gulls who cannot interbreed, but if you follow breeding pairs round the world you can go from one type to the other.
Species is a human taxonomy which doesn't strictly relate well to the variety of organisms in the living world. There are lots of different definitions and ways to approach it depending on context.
The term of art here is "species concept", of which there are several, well covered in [1]. Interfertility is a feature of some, but not all.
[1] https://bio.libretexts.org/Courses/University_of_California_...
[1] https://bio.libretexts.org/Courses/University_of_California_...
In general, in biology species are not defined by the impossibility of having viable hybrids between them, but by the fact that in natural conditions they do not normally interbreed, which allows their genes to drift away, becoming more and more different with the passing of time.
For a species to exist, interbreeding must be both possible and frequent, which ensures that the entire population of the species remains uniform genetically for as long as the species exists, even when its genes may become more and more different from those of other species.
The most frequent way for a new species to appear is when there is geographic isolation between two populations, which prevents interbreeding. Then, after many generations, the genetic differences may become so great that even when the populations are reunited interbreeding will fail, resulting in hybrids that are either non-viable, or sterile, like mules.
With Neanderthals and Denisovans, the geographic separation has started the process of development of new species and they have become clearly differentiated from a genetic point of view.
Nevertheless, not enough generations had passed so that the differences would become so great as to make interbreeding impossible. Even if we know that successful interbreeding has existed, we do not know which was the percentage of success for such interbreeding, i.e. how many of the hybrids were both viable and non-sterile.
So it is a rather arbitrary choice to decide whether to call Neanderthals and modern humans as different subspecies or different species. In any case, they were easy to distinguish.
There are many closely related species between which interbreeding is easily performed in captivity, e.g. in zoos, but it almost never happens in natural conditions, where wild animals may choose partners according to their preferences, so those species are easily distinguishable, due to their genetic differences that are preserved by the lack of interbreeding.
For a species to exist, interbreeding must be both possible and frequent, which ensures that the entire population of the species remains uniform genetically for as long as the species exists, even when its genes may become more and more different from those of other species.
The most frequent way for a new species to appear is when there is geographic isolation between two populations, which prevents interbreeding. Then, after many generations, the genetic differences may become so great that even when the populations are reunited interbreeding will fail, resulting in hybrids that are either non-viable, or sterile, like mules.
With Neanderthals and Denisovans, the geographic separation has started the process of development of new species and they have become clearly differentiated from a genetic point of view.
Nevertheless, not enough generations had passed so that the differences would become so great as to make interbreeding impossible. Even if we know that successful interbreeding has existed, we do not know which was the percentage of success for such interbreeding, i.e. how many of the hybrids were both viable and non-sterile.
So it is a rather arbitrary choice to decide whether to call Neanderthals and modern humans as different subspecies or different species. In any case, they were easy to distinguish.
There are many closely related species between which interbreeding is easily performed in captivity, e.g. in zoos, but it almost never happens in natural conditions, where wild animals may choose partners according to their preferences, so those species are easily distinguishable, due to their genetic differences that are preserved by the lack of interbreeding.
To add to this, an example of 2 species which are easily distinguishable but can produce viable offspring (though the males are usually infertile) are Ligers (Lion + Tiger hybrids)
Lions and Tigers are distinct enough that I don't believe anyone has made the argument that they're the same species. Though I do now wonder if they're really as distinct from one another as different breeds of house-cats
Lions and Tigers are distinct enough that I don't believe anyone has made the argument that they're the same species. Though I do now wonder if they're really as distinct from one another as different breeds of house-cats
So where there humans walking around that had obvious neanderthal-like characteristics but not neanderthal?
What does "neanderthal" mean in this context?
eg: at some point there were humans who, genetically were 100% neanderthal and other humans who were genetically 100% not.
The first pair that mated had offspring with a 50-50 mixture of more or less random neanderthal and "not-neanderthal " genes (although even that is a simplification as the two parents would have had many common human genetic features).
Over the course of seven thousand years of side by side interbreeding and co-habitation there would have been individuals with ranging from 0% neanderthal to 0% "not neanderthal".
A further complication is the relationship between "features" (visible physical characteristics) and "percentage neanderthal" .. an individual may have almost no neanderthal genetics whatsoever save for that one gene that strongly codes for a "neanderthal forehead".
If there was some unique "neanderthal feature" that was clearly recognisable as neanderthal and only expressed itself within people that had some specific "neanderthal gene" ..
Then no, there wouldn't be people walking about with that specifically "neanderthal feature" unless they also had that specific "neanderthal gene".
The problem is that genetic expression really isn't this cut and dried, nor is the boxing up of humans as "this" or "that".
eg: at some point there were humans who, genetically were 100% neanderthal and other humans who were genetically 100% not.
The first pair that mated had offspring with a 50-50 mixture of more or less random neanderthal and "not-neanderthal " genes (although even that is a simplification as the two parents would have had many common human genetic features).
Over the course of seven thousand years of side by side interbreeding and co-habitation there would have been individuals with ranging from 0% neanderthal to 0% "not neanderthal".
A further complication is the relationship between "features" (visible physical characteristics) and "percentage neanderthal" .. an individual may have almost no neanderthal genetics whatsoever save for that one gene that strongly codes for a "neanderthal forehead".
If there was some unique "neanderthal feature" that was clearly recognisable as neanderthal and only expressed itself within people that had some specific "neanderthal gene" ..
Then no, there wouldn't be people walking about with that specifically "neanderthal feature" unless they also had that specific "neanderthal gene".
The problem is that genetic expression really isn't this cut and dried, nor is the boxing up of humans as "this" or "that".
Would it be like a Savannah cat (https://en.wikipedia.org/wiki/Savannah_cat)?
While that's a good looking cat, perhaps more like a Red Dwarf Cat (Felis Sapiens).
Oh there is more to humanity than that. For example the history of europe with even yamnaya, corded-ware, EHG, ANF all looked different with different heights, skin tones, skull shapes, cultures, etc as well.
And this is from around 3000 BC. Modern european as you know it (admixture wise) would likely be fully formed at around 400 BC
And this is from around 3000 BC. Modern european as you know it (admixture wise) would likely be fully formed at around 400 BC
The ~2% that is kept in some humans and I have them and am walking among you. The majority of dna has to do with non-visible changes.
Considering we only differ from chimps by about 4% in genome or less, this is really fine grained analysis.
Guess maths stats & modelling play a big role. Which means some other experts will conclude differently from same data.
Guess maths stats & modelling play a big role. Which means some other experts will conclude differently from same data.
>Considering we only differ from chimps by about 4% in genome
from what I understand, while human males differ from male chimps by about 1% in genome*, that still means that human males are more closely related to male chimps than they are to human females.
* https://knowyourdna.com/human-and-chimpanzee-dna/
from what I understand, while human males differ from male chimps by about 1% in genome*, that still means that human males are more closely related to male chimps than they are to human females.
* https://knowyourdna.com/human-and-chimpanzee-dna/
> while human males differ from male chimps by about 4% in genome, that still means that human males are more closely related to male chimps than they are to human females
These comparisons are stupid. How do you compare the similarity of books? Letter counts? Word counts? Is Romeo & Juliet more similar to Captain Underpants than its own translation into Italian?
These comparisons are stupid. How do you compare the similarity of books? Letter counts? Word counts? Is Romeo & Juliet more similar to Captain Underpants than its own translation into Italian?
No, it's like comparing editions of basically the same book ("Hominid"), with some paragraphs using slightly different wording, a phrase added or removed here and there, old typos fixed, new typos added, etc. It's still largely the same book, but the tone is different in some key places, and the finale leaves a very different impression as a result.
Homo sapiens is wildly different from apes physiologically. (Apes look more anthropomorphic in our perception than dogs or cats, but this means nothing. Humans find two dots and a circular arc to be anthropomorphic too.)
Homo sapiens are apes and are also virtually identical in physiology compared to other apes if the external comparison group is dogs or cats.
And more specifically they are comparing human one who has two copies of chapter x to human 2 who has a new chapter y and the chimpanzee who also has a chapter y, and saying aha look how different males are.
> still largely the same book
What is your metric?
The point is our measures of genetic “distance” aren’t precise enough to make statements like OP’s. At least half of it is eukaryotic operating code, and much of the remaining is “junk” DNA we’re only beginning to understand
What is your metric?
The point is our measures of genetic “distance” aren’t precise enough to make statements like OP’s. At least half of it is eukaryotic operating code, and much of the remaining is “junk” DNA we’re only beginning to understand
Imagine running a diff but with nucleotides.
I thought geneticists already do that?
> Imagine running a diff but with nucleotides
That's my point. Two different books of similar length in the same language will probably diff more closely than the same book translated. (Even if we limit ourselves to the same character set.) That says nothing about the content, just the encoding.
That's my point. Two different books of similar length in the same language will probably diff more closely than the same book translated. (Even if we limit ourselves to the same character set.) That says nothing about the content, just the encoding.
The analogy breaks down because there’s really only one language when it comes to interpreting nucleotide sequences.
How could that be? The only genetic difference is the presence of the Y chromosome. If it were the same size as all the others, it would be a 1/46 difference, so about 2%. But it is smaller than all the others, so maybe 1% or even less difference . The other 45 chromosomes are the same for men and women.
The point is that females have 46 full chromosomes and males don't.
If you take into account that one of the 46 is essentially inactivated in females, that's obviously another story; but as far as nucleotides go, the genetic difference between male and female humans is 1/46th.
If you take into account that one of the 46 is essentially inactivated in females, that's obviously another story; but as far as nucleotides go, the genetic difference between male and female humans is 1/46th.
2.2% > 1%
what is the best explanation for this closeness? the only two species capable of engaging in organized warfare? humans and chimps.
how likely is it that an intelligent entity that precedes humanity came along and decided to chose chimpanzees to breed with?
anybody telling you they know what happened before the time we had written records are selling you something.
how likely is it that an intelligent entity that precedes humanity came along and decided to chose chimpanzees to breed with?
anybody telling you they know what happened before the time we had written records are selling you something.
> anybody telling you they know what happened before the time we had written records are selling you something.
Right, so plate tectonics didn't happen because nobody wrote it down when America and Africa gradually separated? Supernovas didn't happen in the past because even though we can see the remains, nobody wrote it down thousands of years ago? (except for when they did, as for SN 1054)
Right, so plate tectonics didn't happen because nobody wrote it down when America and Africa gradually separated? Supernovas didn't happen in the past because even though we can see the remains, nobody wrote it down thousands of years ago? (except for when they did, as for SN 1054)
do plate tectonics have DNA?
Actually there's very little material to go by as experts say. Fossils of apes are rare and those with DNA are rarer.
Point is media and charlatans will use these research, add their own bs & start unscientific fads, racial theories or paleo diet sort of scams.
That's the concerning part - research can go on, present new info etc that's welcome.
Point is media and charlatans will use these research, add their own bs & start unscientific fads, racial theories or paleo diet sort of scams.
That's the concerning part - research can go on, present new info etc that's welcome.
Humans and Chimps became separate species around 6 million years ago.
https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_...
https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_...
I'll take reasoned theory with bounds and uncertainties over pre-historic fanfiction.
So did homo sapiens invent writings ?
Yes. A very long time after Neanderthals were extinct though, so I don't see the relevance.
Ah i think writings is nessessary for not being extinct.
>Ah i think writings is nessessary for not being extinct.
Give the poor quality of your writing, are you sure you're not extinct?
Give the poor quality of your writing, are you sure you're not extinct?
I am not sure.
>Ah i think writings is nessessary for not being extinct.
Tell that to the sharks[0].
[0] https://www.nhm.ac.uk/discover/shark-evolution-a-450-million...
Tell that to the sharks[0].
[0] https://www.nhm.ac.uk/discover/shark-evolution-a-450-million...
[deleted]
I always thought of the interbreeding of Homo Sapiens and Neanderthals as being a sort of “one off event” or something. I mean, obviously not literally just once, but maybe some little era, part of the process of us wiping them out.
But, 7000 years is a while. I mean, how long has our current civilization lasted? I guess it depends on how you define it. But certainly that coexistence, whatever it was, lasted longer than any countries or other institutions have…