Did Upper Paleolithic Human Fossils Undergo Hybridization?

A new study published in Nature Ecology and Evolution focused on the effects of hybridization using fossil skulls and identified specific potential hybrids in the past. To understand the impacts of such hybridization and what makes us human, it is essential to investigate the effects by utilizing a range of evidence.

(Photo: Artist: John GurchePhotographer/Wikimedia Commons)
Homo Neanderthalensis Adult Male Reconstruction

Ancient DNA Evidence

It is possible to understand how our genes have evolved due to environmental adaptation by studying the genetics of ancient humans and animals using ancient DNA. According to Cosmos Magazine, the bone or tissue of a museum specimen or other sorts of preserved remains can be used to isolate ancient DNA.

In this study, the researchers examined a wide variety of Upper Paleolithic human fossils from Eurasia, which date from between 40 and 20 thousand years ago. Numerous of these people have provided ancient DNA evidence.

It reveals a minor amount of Neanderthal heritage in their genes, indicating recent hybridization with this population. Their skull bones were compared to Neanderthals, early modern humans, and more recent modern humans from Africa. Although they were human like us, according to the Natural History Museum, neanderthals belonged to a separate species known as Homo neanderthalensis.

Evidence of Hybridization

The mandible, the braincase, and the face were the three areas of the skull that the researchers looked at for telltale evidence of hybridization. These are characteristics we see in hybrids of numerous mammals, including primates: These can include intermediate morphology relative to Neanderthals or modern humans, dental anomalies, or uncommon sizes. Professor Katerina Harvati and Rebecca R. Ackermann's research revealed that faces did not exhibit signs of hybridization, unlike brain cases.

Skeletal Evidence of Hybridization

The researchers also considered whether the amount of Neanderthal ancestry in the individuals with known genetic backgrounds matched any skeletal evidence of hybridization. Since it didn't, the researchers conclude that the presence of specific genetic variations is probably more relevant than the overall fraction of Neanderthal ancestry.

Although it is well known that the groups interact in the Middle East, Harvati and Ackermann also found people from beyond the region in Western and Eastern Europe as likely hybrids.

According to Harvati, individual hybrid status should, if possible, be confirmed using genetic data. As a result, they view these identifications as testable hypotheses. Because this was the first study of its kind, the researchers hope to encourage academics to examine these fossils more carefully and integrate several lines of evidence to find hybridization in the fossil record.

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Skeletal Evidence of Hybridization

It is well recognized that hybridization promotes evolutionary innovation in other organisms, resulting in novel and varied outcomes in anything from plants to huge mammals.

Ackermann estimates that about 10% of animal species produce hybrid offspring, including bovids, bears, cats, and canids. She asserts that baboons and other close relatives of humans, primates, are examples of hybrids.

Hybridization might encourage rapid evolution when faced with novel or changing environmental conditions. The authors speculate that hybridization may have given early humans genetic and anatomical traits that offered them significant benefits as they migrated from Africa throughout the globe, giving rise to our physically diversified and hardy species.