A group of scientists has found clues in blood groups that explain how modern humans managed to survive and expand from Africa to the rest of the world. Published in the journal Scientific Reports, the study compares the genes of the blood groups of Homo sapiens and Neanderthals to better understand our history as a species.
Blood groups, such as ABO and Rh, are not only used to determine what type of blood we can receive in a transfusion. They also serve as a window into the past, showing how humans adapted to diseases and new environments. This study focused on 22 Homo sapiens and 14 Neanderthals who lived between 120,000 and 20,000 years ago.
When Homo sapiens left Africa around 70,000 years ago, they carried with them new genetic variants that helped them survive in different climates and resist diseases. In contrast, Neanderthals, who had already been living in Eurasia for a long time, did not develop as much diversity in their blood groups.
One of the biggest differences between Homo sapiens and Neanderthals lies in their ability to adapt. Homo sapiens had a greater variety of genes in their blood groups, allowing them to better face new challenges. For example, sapiens carried genes that protected them against diseases in different parts of the world.

Neanderthals, on the other hand, retained older and less varied genes. One example is a gene related to the Rh system that is still present in some people in Oceania. This gene likely reached them through interbreeding between sapiens and Neanderthals thousands of years ago.
While Homo sapiens continued evolving and adapting, Neanderthals faced greater difficulties surviving in a rapidly changing world. This may have been one of the reasons for their extinction.
Genetic diversity in Homo sapiens was key to their evolutionary success, while the genetic stability of Neanderthals may have limited their ability to adapt to rapid changes, the authors explain.
The study also found genes in ancient humans that are no longer present in modern humans. These genes may be part of lineages that disappeared over time. For instance, a human named Ust’Ishim, who lived in Siberia 45,000 years ago, had unique genes that are not found in anyone alive today.
Understanding past blood groups not only helps us learn about our history but also has practical applications today. For example, understanding how these genes evolved can improve the safety of blood transfusions and treatments during pregnancy.
Additionally, studying how ancient humans protected themselves from diseases can provide insights into tackling current health issues. One well-known case is the Duffy system, whose genes help some people in Africa resist malaria.
Thanks to these discoveries, we can better understand how our species managed to conquer the world and face the challenges it encountered along the way, the researchers conclude.
SOURCES
Mazières, S., Condemi, S., El Nemer, W. et al. Rapid change in red cell blood group systems after the main Out of Africa of Homo sapiens. Sci Rep 15, 1597 (2025). doi.org/10.1038/s41598-024-83023-0
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