Interbreeding Events and Introgression

The intermingling of these two species initiated a phenomenon known as introgression, characterized by a gradual exchange of genetic material. Until 2016, it was generally accepted that anatomically modern humans began mating with Neanderthals approximately 50,000 to 60,000 years ago. However, a groundbreaking study published in the journal "Nature" revealed that such interactions may have taken place as much as 50,000 years earlier.

New research presented in "Current Biology" suggests that this interbreeding event could date back as far as 250,000 years. A collaborative study by the University of Pennsylvania involved comparing the genome of a Neanderthal from 120,000 years ago in Siberia with the genomes of modern humans from Sub-Saharan Africa. This work sheds light on human migration patterns.

"In our statistical analysis, we aimed to ascertain whether specific genetic variants originated from Neanderthals and entered modern human populations, or the other way around," explained Alexander Platt, the lead author and evolutionary biologist at the University of Pennsylvania.

The comparative analysis of Neanderthal and modern human genomes reveals a history of genetic exchange that transpired soon after Homo sapiens migrated from Africa into Eurasia, as stated by the researchers in their findings. It is emphasized that while this group of humans has since vanished, their genetic legacy persists in the Neanderthal genome.

An Unknown Lineage of Homo sapiens

The researchers propose that a previously unidentified lineage of modern humans migrated to Eurasia over 250,000 years ago, which contradicts earlier research timelines. They theorize that when these early Homo sapiens began their mass migrations and mingled with Neanderthals, their genetic heritage already included traits from modern humans.

"This unknown group of early humans departed Africa approximately 250,000 to 270,000 years ago. They can be considered cousins to all living humans today, exhibiting a closer genetic relationship to us than to Neanderthals," remarked Alexander Platt.

Although this hypothesis is ambitious, supporting evidence has been gathered. Scientists conducted genomic analyses of 180 individuals from a dozen genetically diverse populations in Botswana, Cameroon, Ethiopia, and Tanzania.

Back-and-Forth Migrations

The research team discovered that roughly 6% of the Neanderthal genome from Siberia was derived from this extinct lineage of modern humans. They also identified about 1.5% of this genetic material in contemporary populations in Ethiopia and Cameroon. This raises the question: how did Neanderthal genes find their way to Africa, considering that the two species primarily interbred in Eurasia?

The researchers hypothesize that Homo sapiens may have returned to Africa during their migrations. "This discovery highlights the importance of incorporating diverse ethnic and geographic groups into discussions surrounding human genetics," stated Sarah Tishkoff, a geneticist from the University of Pennsylvania and co-author of the study. "We lack sequenced DNA from modern humans of such ancient origin, so identifying this lineage could provide new insights into the early evolution of humans in Africa," concluded Daniel Harris from the University of Pennsylvania.

This video discusses the intriguing question of whether early humans and Neanderthals exchanged artistic ideas, exploring their interactions through the lens of art and culture.

The second video delves into the possibility of Neanderthal migration to Africa 250,000 years ago, examining the evidence and implications of such movements in human history.