How Blood Group Differences Could Have Led to Neanderthal Extinction?
A fascinating new study suggests that a crucial difference in blood group red blood cells may have played a key role in the extinction of Neanderthals. When modern humans first left Africa, they experienced rapid evolution in their blood cells, which helped them survive. But this same evolution may have contributed to the demise of Neanderthals.
Neanderthals’ Rare Blood Group
Researchers from Aix-Marseille University in France recently sequenced the genomes of people who lived between 120,000 and 20,000 years ago. They discovered that Neanderthals had a rare Rh blood group that might have been fatal to their newborns. This discovery was published in Scientific Reports in January 2023.
Blood Groups and Antigens
Blood group types are determined by antigens, which are proteins and sugars found on the surface of red blood cells. Most people are familiar with the ABO system, which categorizes blood into A, B, AB, and O groups. Additionally, the Rh factor indicates whether blood is positive or negative, influencing compatibility in blood transfusions.
But beyond these common blood types, there are hundreds of lesser-known blood cell antigens. These variations are inherited and have played a crucial role in human evolution.
Neanderthal vs. Modern Humans’ Blood Types
The researchers found that Neanderthals had an Rh variant, specifically RhD, which is rare in modern humans. This Rh variant was not compatible with the blood types of early Homo sapiens or Denisovans. According to the study, any case of inbreeding between a Neanderthal female and a Homo sapiens or Denisovan male would have led to a condition called hemolytic disease of the newborn. This condition can cause severe health issues like jaundice, anemia, brain damage, and even death.
The Demise of Neanderthals
This incompatibility could have contributed to the Neanderthal population’s decline. Hemolytic disease would have been especially deadly because, unlike today, there were no treatments available to prevent or manage the condition. The lack of blood type compatibility could have significantly reduced Neanderthal reproduction rates, contributing to their eventual extinction.
Why Did Early Humans’ Blood Cells Evolve?
The study also found that the Rh variants present in modern humans likely evolved shortly after our ancestors left Africa, possibly while living on the Persian Plateau. This sudden diversification of red blood cells in early Homo sapiens may have been linked to environmental changes and a demographic expansion. In contrast, Neanderthals remained isolated, with little change in their red blood cell types over the last 80,000 years of their existence.
Conclusion
This research adds another layer of understanding to the extinction of Neanderthals. While we already know that environmental changes and competition with modern humans played a role, the differences in blood types could have been another factor that contributed to their disappearance. The rapid evolution of blood cells in early Homo sapiens might have helped them thrive, while Neanderthals’ lack of genetic diversity in this area could have sealed their fate.
