Your Blood Type Is Not What You Think It Is

You know your blood type. You probably learned it at some routine checkup, wrote it on a form, and never thought about it again. It felt like a category. A label. Administrative information with roughly the same significance as your shoe size. It is not. The blood type running through your body right now is there because a disease moved through your ancestors' population and killed most of the people it touched. The ones it did not kill survived for a reason they could not see, could not name, and could not know. A reason written invisibly into their blood. And they passed it forward through every generation between that moment and you. Your blood type is not a medical category. It is a survival record. In this video we trace exactly how that happened. How the ABO blood type system predates the human species entirely — chimpanzees and gorillas carry it too, suggesting something has been selecting for multiple blood types across 20 million years of primate evolution. How the Black Death shifted the genetic composition of every European population it passed through measurably, documentably, in ways still visible in skeletal remains. How blood type distribution across the world today is a precise map of which ancient epidemics killed whom and which blood variants happened to resist them. And how modern research has confirmed that the same selection pressure is still active your blood type is still conferring the resistances and susceptibilities that thousands of years of epidemic pressure wrote into it. The medical label is four characters long. The story behind it is thousands of years old. And it is running through you right now. References Calafell, F. et al. (2008). Evolutionary dynamics of the human ABO gene. Human Genetics, 124(2). — ABO system's 20-million-year primate evolutionary history. Segurel, L. et al. (2012). Balancing selection of the ABO blood group in humans and primates. PLOS Genetics. — Natural selection maintaining ABO polymorphism across primate lineages. Alfano, M. et al. (2021). ABO blood group and COVID-19: a review on behalf of the ISBT COVID-19 working group. ISBT Science Series. — Blood type and COVID-19 susceptibility across multiple population studies. Klüter, H. et al. (2021). ABO blood group and SARS-CoV-2 susceptibility. Blood Reviews. — Type O lower risk of severe COVID-19 outcomes replicated across countries. Livingstone, F.B. (1960). Anthropological implications of sickle cell gene distribution in West Africa. American Anthropologist. — Disease pressure and blood variant distribution in sub-Saharan populations. Novembre, J. et al. (2005). The geographic spread of the CCR5 Delta32 HIV-resistance allele. PLOS Biology. — Disease-driven selection shaping population genetics over historical timescales. Krause, J. et al. (2020). A genomic history of ancient Europe. Nature. — Pre and post-plague genetic composition shifts in European skeletal remains. #AncientHumans #HumanBiology #BloodType