The blood groups of Homo Sapiens shed light on the reasons for its evolutionary success

The blood groups of Homo Sapiens shed light on the reasons for its evolutionary success
The blood groups of Homo Sapiens shed light on the reasons for its evolutionary success

Analysis of the blood groups of the first Homo sapiens D'Eurasie shows that they have acquired a new palette of blood groups just after their release from Africa 60,000 years ago, contrasting with that of Neanderthals. This diversification would have occurred in the Middle East and could endow Homo sapiens of a new adaptive arsenal. This is revealed by the study made by our team from the biocultural, law, ethics and health anthropology laboratory. This study has just appeared in the review Scientific Reports.


The Upper Paleolithic (around 45,000 to 10,000 years before the present), known for its caves decorated with Chauvet, Cosquer, Niaux and Lascaux, is a pivotal period of human evolution. Eurasia, then occupied by Neanderthal et Denisovasees arriving Homo sapiensover 45,000 years ago. Cohabitation lasts until the disappearance of Denisova in Asia and Neanderthal In Europe, a few 35,000 years ago.

Despite their seniority and fragmentary bone remains, previous studies have succeeded in obtaining DNA in more than 60 individuals from these three human lines. From these sequences, our team wanted to see how the transition from Neanderthal has Homo sapiens was manifested for blood groups.

What are blood groups?

Blood groups (like O+ or A-) are labels on the surface of red blood cells which define a “type” of red blood cells. When a type of red blood cells come into contact with a person who does not have it, as in a transfusion error or pregnancy, this can cause a sometimes lethal reaction to the receiver or the newborn. For the latter, it is the hemolytic disease of the newborn. It occurs when the blood groups of the fetus differ from those of the mother. The latter can then create antibodies against these blood groups which she does not know. During the following pregnancies, the mother's antibodies can destroy the red blood cells from her fetus.

Blood groups are grouped into families called systems. Groups A, B, O and AB belong to the ABO system. The positive and negative “rhesus” belong to another system, called HR. To date, there are 47 systems of which are truly crucial in transfusion. In our study, we are focused on 10 of these systems.

Why take an interest in blood groups today, when they have been known for almost a century?

When the scientific community did not yet know how to read the DNA sequence, the blood groups indirectly made it possible to study human genetic variability. Thus, they revealed the history of the population of the earth by Homo sapiensthe stigma of adaptation to tropical climates and the inanity of the concept of race. For example, it was the blood groups which, in the 1950s, demonstrated the Asian origin of all the Amerindian populations of the American continent. These elements are gathered in the works of Arthur dying of 1976 and that of Luca Cavalli-Sforza from 1994.

But from the 1990s, the emergence of molecular biology preferred to them mitochondrial DNA and the Y chromosome. These genetic markers have more genetic variation and are only transmitted by a single parent, respectively the woman and the Man, which allows generations to be raised without losing genetic information. Blood groups are then relegated to their main application, blood transfusion.

It is the advent of paleogenetics and sequencing of total genome that will restore the anthropological interest of blood groups. Indeed, molecular biology provides access to immense diversity. The blood groups which appeared to be identical are actually coded by a wide variety of their gene. For example, groups A, B, AB and O do not come from 4 versions of the ABO gene, but from more than 350 forms of this gene! And their geography is revealing of the story ofHomo sapiens. By reading the genes of the blood groups, our team notably refined the history of the population of America, that of Central Asia by the nomads of the Mongolian steppes (Gengis Khan) and the contact with Neanderthal.

Finally, large amounts of genetic data are now available with more than 10,000 old genomes. But despite first convincing results, the genetic and anthropological reading of blood groups is recent and still concerns few research teams in the world.

How to determine prehistoric blood groups

For old subjects, if red blood cells are not preserved, bone or dental fragments may contain organic matter with DNA. And this DNA has already been sequenced. These sequences are available online on platforms such as the European Nucleotide Archive or the server of the evolving genetic department of the Max Planck Institute. Some of these DNAs are of excellent quality, that is to say complete and and for which the community is very confident on the content of the sequence.

We know the genes of the blood groups, the chromosomes that carry them, their contact details, and the mutations behind the blood groups. So we downloaded each genome and asked to see the DNA sequence for each position of interest. Then, we compared each prehistoric sequence with the current human sequence used as an international reference. To do this, we used special bioinformatic commands and alignment tools or sequence comparator. Then we transcribed the sequence of interest, the number of times it has been sequenced and statistical clues to guarantee the likelihood of the result.

-

In the end, we were able to obtain usable results for 22 Homo sapiens And 14 Neanderthals, aged 20,000 to 120,000 years, and located in Western Europe, Central Europe, Siberia and East Asia.

In Eurasia, the current distribution of blood groups comes from the first sapiens on the continent

The study shows thatHomo sapiens experienced intense diversification after its release from Africa, 60,000 years ago, with blood groups that Neanderthals do not have. The latter have notably kept the same ancestral blood groups for 80,000 years! The two lines therefore have completely distinct blood profiles.

This genetic diversification would have occurred between 60,000 and 45,000 years. A recent study has shown that the Persian plateau would be the region of incubation for archaeological cultures and genetic lines of the first Homo sapiens. Before conquering Eurasia, Homo sapiens would then have marked a stop on the Persian set, long enough to develop new technologies and genetic mutations. Blood groups of the first Homo sapiens would therefore have known this phase of diversification.

These new blood groups, such as a particular O group and certain rhesus, are now widespread in Eurasia up to more than 40 % while they are absent in Africa. The current geography of blood groups in Eurasia is not recent, but therefore dates back to “Out of Africa”.

Are these blood groups advantageous for the first sapiens?

If the appearance of a mutation is chance, its destiny then is two factors: drift and natural selection. Drift is again by chance. The mutation has no effect and its presence in the population fluctuates randomly over the generations. Natural selection is the impact of the environment such as altitude or pathogens on genetics.

Nowadays, certain blood groups give an advantage in the face of pathogens such as cholera, malaria, one of the gastroenteritis viruses and we have seen it recently, COVVID. We then imagine that the blood groups found in the first Sapiens were able to provide them with a new arsenal to deal with the new environments encountered during its expansion around the world. On the other hand, it is too early to decide on the responsible pathogens (s).

The fascinating story of Neanderthal's “rhesus”

Neanderthals share the same “rhesus” gene. Parent of one of the African “rhesus”, it is today almost unprecedented worldwide with the exception of two cases in Australia and Papouasie-Nouvelle-Guinea. Oceania is also the region of which the populations have the most important Neanderthal and Denisovian genetic heritage, up to 6 %. Thanks to this Neanderthal “rhesus”, we have updated the evolutionary scheme of this blood group: the Neanderthal gene has in reality encrusted in the genome by mixing, probably after Africa beforeHomo sapiens Do not migrate to Oceania over 50,000 years ago.

Eurasia settlement model by Homo sapiensseen by blood groups.
Stéphane Mazières

In practice, “rhesus”, like that of Neanderthal, are involved in the hemolytic disease of the newborn. Our study shows that the first Sapiens Eurasia do not have it. In the event of a mixture between a sapian man and a Neanderthal woman, there would therefore be a risk of losing the child. The Neanderthal “rhesus” could therefore have contributed to their decline when the Homo sapiens.

Lost genetic lines

The Siberian individual of Ust'-Ishim, dated approximately 45,000 years, is known to carry a disappeared genetic line, and this shows in our study. It has unique blood groups, not found among more recent prehistoric populations. Like the results published in December 2024 in magazines Science et Natureour study confirms that the population of Eurasia was not a continuous process, but rather a series of waves interspersed with replacements and local extinctions.

The red blood cell has many variations in response to malaria. But the origin and dates of these biological adaptations remain discussed. Access to ancient genomes offers an opportunity to explore another story: relations between prehistoric humans and infectious diseases.

-

--

PREV The Casablanca-Settat region approves the strengthening of infrastructure
NEXT Dordogne, what will the weather be like this Friday January 24?