The three parts of this article first confirm the communication, and then say why
There must have been genetic exchange between Homo sapiens and Neanderthals
———— modern humans do contain other ancient human DNA————
Today, there are about 2% Neanderthal components in the human body, and it is impossible without genetic communication.
(Neanderthal restoration)
Earlier this year, Nature had a roundup on human origins that was well written
All non-African individuals studied so far contain around 2% Neanderthal ancestry
Not only that, but the article also believes that the neanderthal ingredients in homo sapiens may have been as high as 10% in the body of Homo sapiens.
the proportion of Neanderthal DNA in humans might originally have been as high as 10%
In fact, not only Neanderthals, but also Denisovans, who contribute, such as Melanesians, who have 3-6%
Similar to Neanderthals, Denisovans interbred with anatomically modern humans. About 3–6% of the genome of some groups of people, including Melanesians in Oceania, can be traced to a Denisovan-like ancestor。
(Schematic of denisovans)
———'ve been apart for a long time———
But these ancient humans are indeed a little far away from us.
The figure above provides a more vivid picture of the separation of these human beings.
I marked the ancient humans in the red box Neanderthals, Denisovans, and unknown Terran compositions. They separated from us for more than 400,000 years (even 600,000 years in the picture).
So, it's embarrassing.
What exactly is the relationship between Homo Sapiens and Homo neanderthalensis?
Although we have done a lot of research on the Nepalese people, such as measuring the genome and building a database
However, there are multiple views at this time.
Some people think that the two are subspecies, just like the Qinling giant panda and the Sichuan giant panda, such as Yan Bo, who holds this view.
A significant number of people still insist that Neanderthals are a species, not a subspecies
Neanderthals and modern humans belong to the same genus (Homo) and inhabited the same geographic areas in Asia for 30,000–50,000 years; genetic evidence indicate while they may have interbred with non-African modern humans, they are separate branches of the human family tree (separate species)
(Abbreviation, Neanderthals and modern humans belong to the human genus, and genetic evidence suggests that they are independent species)
—————— reproductive isolation is the only criterion for subspecies——————
When defining subspecies, there is a reproductive isolation item. However, reproductive isolation does not mean infertility.
If isolation occurs before fertilization, it is called pre-fertilization reproductive isolation, including geographical isolation, ecological isolation, seasonal isolation, physiological isolation, morphological isolation and behavioral isolation; if isolation occurs after fertilization, it is called reproductive isolation after fertilization, including heterosis inactivity, heterosis and heterosis decay.
The isolation of many subspecies is only geographical isolation, and once they are gathered together, they can snap and grow.
At this point, the question arises, is reproductive isolation the only criterion for subspecies? Even, are there intermediate species?
In fact, in nature, it is indeed so magical, so the creatures rule all kinds of disobedience.
There is a content called the intermediate form, which should be seen from this name, which means that this is a transitional state.
In nature, the emergence of species occurs gradually, then, it may be that there is a species that is about to become a new species, but has not yet formed.
A review of nature review genetics in 2014 seehausen-Genomics and the origin of species
The article elaborates on the existence of this intermediate pattern.
The ab two diagrams are two mechanisms for establishing reproductive isolation. In the same graph, the left side is the group that has not yet differentiated, the right side is the group that has been completely differentiated, and the middle one is the transitional state. In the same picture, on the left are the groups that have not yet begun to differentiate, on the right are the two species that have completed the differentiation, and in the middle are the specific processes of speciation. The Latin section below the figure is the name of some species
In other words, in living things, there is such a transitional form.
The most typical is the existence of ring species Ring species - Wikipedia
The so-called ring species: all two groups that are geographically adjacent can be hybridized, and those that are not adjacent cannot be crossed, and there is a pair of such groups/species called "end points" that cannot be crossed.
Gull birds, for example, are like this
The picture below is 7 kinds of gull birds, 1 and 2 can be snapped, 2 and 3 can be snapped, but 1 and 3 are not ok, 1 and 4 are not ok, and so on. It turned out to be 1 and 7, and I didn't even know my mother...
（The Larus gulls interbreed in a ring around the arctic. 1: L. fuscus, 2: Siberian population of Larus fuscus, 3: L. heuglini, 4: L. vegae birulai, 5: L. vegae, 6: L. smithsonianus, 7: L. argentatus.）
————— Conclusion—————
From the above discussion, we can see
1, modern Homo sapiens and Neanderthals have actually been separated for a long time (hundreds of thousands of years), distributed in the African continent and Eurasia, as shown in the figure below, which is the geographical isolation in the real reproductive isolation
2, at the genetic level, the difference between the two to the separrate species
3, Neanderthal itself can produce genetic communication with modern people
So, I think the relationship between Homo sapiens and Neanderthals should look like this:
[Above subspecies, below species] may be a transitional form between subspecies and species.
ps: species are defined by reproductive isolation, although simple and crude, but often difficult to implement, and there are many problems, with the development of genetics, there will inevitably be new taxonomy.