For years, scientists have mostly been in agreement with the timelines for the so-called “Out of Africa” theory of modern human origin; Homo sapiens had most likely evolved in Africa, then migrated en masse to what is now known as Asia approximately 60,000 years ago. But a new study suggests that this diaspora took place at a much earlier time, and that there might have been multiple migrations, as opposed to one singular wave.
The “Out of Africa” theory has been around for slightly less than 100 years, with scientists basing their timelines on early hominin fossils found in South Africa in the 1920s. According to Discover magazine, such ideas were initially met with disdain and ridicule, but were eventually accepted by most experts in the years that followed, as more fossils were found in eastern Africa, hinting at the region being a possible “cradle of humanity.”
While the new study does not dispute the idea that modern humans originated from Africa, it significantly revises the timeline of the great migration from Africa to Asia, while also suggesting the possibility that there was more than one migration that took place. According to the paper published earlier this week in the journal Science, discoveries from the last decade point to a series of migrations out of Africa that happened between 70,000 to 120,000 years ago. This new theory is based on fossils that researchers found in southern and central China, dating back to the newly proposed timelines for the migrations.
“The initial dispersals out of Africa prior to 60 000 years ago were likely by small groups of foragers, and at least some of these early dispersals left low-level genetic traces in modern human populations,” explained researcher Michael Petraglia of the Max Planck Institute for the Science of Human History, as quoted by Phys.org.
“A later, major ‘Out of Africa’ event most likely occurred around 60 000 years ago or thereafter.”
Aside from revising old theories by hinting at multiple migrations, the researchers also discovered more evidence pointing to interbreeding between modern humans and Neanderthals, Denisovans, and other hominin groups. According to Quartz, these findings offer more proof of frequent interactions between modern humans and other groups while in Asia.
With the new “Out of Africa” theory suggesting several instances of interaction and possible interbreeding between Homo sapiens and hominin groups, University of Hawaii researcher and study co-author Christopher Bae said in a statement that the spread of modern human behaviors is more complex than once thought, and may not have taken place in a “time-transgressive” fashion, where such behaviors were spread over time as Homo sapiens migrated from west to east.
Given the proverbial thickening of the “Out of Africa” plot suggested by the new study, there are still several questions that do not have a definitive answer. This has prompted the authors of the paper to call for more complex human dispersal models, and for additional research to be carried out in various parts of Asia that have yet to be explored. The researchers also believe that materials gathered before the advent of modern analytics need to be reviewed once again, in hopes of gleaning more information about what might have happened when Homo sapiens migrated from Africa to Asia.