Sex with humans caused a blood disease that drove Neanderthals to extinction, study finds

Did sex with modern humans kill the Neanderthals? Crossbreeding could have led to a blood disease in their babies that contributed to their extinction, study finds

  • Interbreeding with modern humans may have driven Neanderthals to extinction
  • New study found it could lead to a blood disorder in Neanderthal babies
  • This would have reduced ‘reproductive success’ and a limited number of offspring
  • It would also have been ‘quite common’ due to the species’ small gene pool

Sex with modern humans may have contributed to the Neanderthals’ extinction, as it could have caused a blood disorder in their babies, scientists have found.

The condition can cause potentially fatal anemia and is often worse in second and subsequent pregnancies, meaning it would have reduced “reproductive success” by limiting the number of offspring Neanderthals could have.

It would also have been “quite common” due to the species’ limited gene pool, researchers said, and is likely to be partly responsible for their demise.

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Theory: Sex with modern humans may have contributed to the extinction of Neanderthals because it could have caused a blood disorder in their babies, scientists have found

WHAT IS THE BLOOD DISORDERS HDFN AND WHY DOES IT HELP KILL NEANDERTHALS?

‘Hemolytic disease of the fetus and newborn’ (HDFN) is a blood disorder that occurs when a mother’s and baby’s blood types are incompatible.

Everyone has a blood type and an Rh factor, which indicates whether they have a specific protein on the surface of their red blood cells. If a person has this protein, which most people do, they are Rh positive.

However, if a woman who doesn’t have the protein gives birth to a man who does have it, the fetus may have a different Rh factor than the mother.

This can cause the mother’s immune system to attack a baby’s red blood cells, resulting in potentially fatal anemia.

The condition is rare today, affecting about three in every 100,000 pregnancies.

However, Neanderthals were particularly prone to it because they carried a specific set of genetic variants with them.

HDFN is often worse in second and subsequent pregnancies, meaning it would have decreased “reproductive success” by limiting the number of offspring Neanderthals could have.

It would also have been “quite common” due to the species’ limited gene pool, researchers said, and is likely to be partly responsible for their demise.

Scientists analyzed the blood types of three Neanderthals and found that they were particularly susceptible to “hemolytic disease of the fetus and newborn” (HDFN) because they carried a specific set of genetic variants.

The condition is rare today, affecting about three in every 100,000 pregnancies.

“The fact that these forms of genes were detected in individuals 4,000 km and 50,000 years apart suggests that this genetic idiosyncrasy – and the risk of [an] anemia fetus — would have been very common among Neanderthals,” said Stephane Mazieres, a lead author of the paper from the University of Aix-Marseille.

While HDFN may have formed when Neanderthals had sex with each other, experts said the risk was “greater” when mating with our ancestors and also with Denisovans, another extinct human species.

“These elements may have contributed to weakening the descendants to the point of their demise, especially when combined with the competition with Homo sapiens for the same ecological niche,” the researchers said.

Everyone has a blood type and an Rh factor, which indicates whether they have a specific protein on the surface of their red blood cells. If a person has this protein, which most people do, they are Rh positive.

However, if a woman who doesn’t have the protein gives birth to a man who does have it, the fetus may have a different Rh factor than the mother.

This can cause the mother’s immune system to attack a baby’s red blood cells, resulting in potentially fatal anemia.

The discovery could provide further clues as to what drove the Neanderthals to extinction about 40,000 years ago.

There are many theories as to what led to their downfall.

Experts have suggested that early humans carried tropical diseases from Africa that wiped out their ape-like cousins.

The predominant theory is that Homo sapiens wiped out the species by competing for food and habitat.

A map showing the relative dates when humans arrived on the various continents 45,000 years ago, including Europe.  Humans and Neanderthals coexisted for about 8,000 years before Neanderthals became extinct

A map showing the relative dates when humans arrived on the various continents 45,000 years ago, including Europe. Humans and Neanderthals coexisted for about 8,000 years before Neanderthals became extinct

Scientists know that Neanderthals and Homo Sapiens interbred because up to 2 percent of the DNA found in modern Europeans and some Asian humans comes from Neanderthals

Scientists know that Neanderthals and Homo Sapiens interbred because up to 2 percent of the DNA found in modern Europeans and some Asian humans comes from Neanderthals

Homo sapiens’ superior brain power and hunting techniques meant that the Neanderthals couldn’t compete.

Based on scans of Neanderthal skulls, a new theory suggests that the heavy-browed hominins lacked key human brain regions essential for memory, thinking and communication skills.

That would have affected their social and cognitive abilities — and could have killed them because they couldn’t adapt to climate change.

Scientists know that Neanderthals and Homo sapiens interbred because up to 2 percent of the DNA found in modern Europeans and some Asian humans comes from Neanderthals.

The latest study, entitled Blood Groups of Neanderthals and Denisova Decrypted, is published in the journal PLoS One.

Neanderthals, a close relative of modern humans, died out 40,000 years ago

The Neanderthals were a close human ancestor that mysteriously died out about 40,000 years ago.

The species lived in Africa for millennia with early humans before moving to Europe about 300,000 years ago.

They were later joined by humans, who entered Eurasia about 48,000 years ago.

The Neanderthals were a cousin of humans, but not a direct ancestor — the two species split off from a common ancestor — who perished about 50,000 years ago.  Pictured is an exhibition of a Neanderthal museum

The Neanderthals were a cousin of humans, but not a direct ancestor — the two species split off from a common ancestor — who perished about 50,000 years ago. Pictured is an exhibition of a Neanderthal museum

These were the original “cave dwellers,” historically stupid and brutal compared to modern humans.

However, in recent years, and especially in the past decade, it has become increasingly apparent that we are failing Neanderthals.

A growing body of evidence points to a more sophisticated and multi-talented kind of “caveman” than anyone thought possible.

It now seems likely that Neanderthals had told, buried, painted and even interbred their dead with humans.

They used body art such as pigments and beads, and they were the very first artists, with Neanderthal cave art (and symbolism) in Spain some 20,000 years older than the earliest modern human art.

They are believed to have hunted on land and did some fishing. However, they became extinct about 40,000 years ago after the success of Homo sapiens in Europe.

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