7,000-Year-Old Mummies
TheSahara is a vast expanse of sand where the fight for survival can be brutal.But there was a time in the distant past when it was green and flourishing.
Backbetween 14,000 and 5,500 years ago, during the African Humid Period, the Saharahad enough water to support a way of life, rather than being one of the driestplaces on Earth. At that time, it was a savannah where early humans settled forthe favorable farming conditions. Among those people was a mysterious sub-groupwho lived in what is now southwestern Libya. Genetically, they should have beenSub-Saharan. But modern analysis shows that their genes don’t reflect that.
A teamof researchers found two 7,000-year-old naturally preserved mummies ofNeolithic female herders at the Takarkori rock shelter. Usually, geneticmaterial does not preserve well in arid conditions, but in this case, there wasenough fragmented DNA to give some insights into their past and clear up someof the mystery of human populations in the Sahara.
The Takarkori individualsdon’t share DNA with modern humans. The majority of their ancestry stems from apreviously unknown North African genetic lineage that diverged from sub-SaharanAfrican lineages about the same time as modern humans roamed outside of Africa.But the Takarkori people appear to have remained isolated throughout most of theirexistence.
These Takarkori individualswere close relatives of 15,000-year-old foragers from the Taforalt Cave inMorocco. Both the Takarkori and the Taforalt people have about the same geneticdistance from Sub-Saharan groups that existed at that time. This suggests therewas not much gene flow between Sub-Saharan and Northern Africa at the time.Also, the Taforalts have half the Neanderthal genes of non-Africans. TheTakarkori have ten times less. But, both of them still have more NeanderthalDNA than other Sub-Saharan peoples who were around at the time. Although theTarkarkori apparently had less contact with Neanderthals than their morewestern brethren, they must have had more contact than other groups in theirregion. There are also traces of evidence of the Tarkarkori mixing with farmersfrom the Levant (the east coast of the Mediterranean Sea). But otherwise, thegenes of the Takarkori reveal they were mostly isolated. Although geneticallyclose to Northwestern African foragers like the Taforalt, they were distinctfrom Sub-Saharan populations.
It appears there wasnot much genetic exchange in the Green Sahara during the African Humid Period.It was thought that farming spread through the region by migrations, but this researchsuggests another explanation. Perhaps pastoralism spread through culturaldiffusion into a deeply divergent, isolated North African lineage that was widespreadin Northern Africa during the late Pleistocene epoch. In other words, farmingspread through the exchange of practices between cultures rather than themixture of people from migrations.
The Takarkori may haveinherited their genes from a hunter-gatherer group from before animals weredomesticated and farming began. Despite being hunter-gatherers, their ancestorsmade advances in making pottery, baskets, and tools made of wood and bone. Theyalso seemed to stay in one place for longer periods of time.
Possibly the Takarkoristayed isolated because of the diversity of environments in the Green Sahara.These ranged from lakes and wetlands to woodlands, grasslands, savannas andeven mountains. Such differences were probably barriers to interactions betweenhuman groups.
Elsewhere in theSahara, there might be additional mummies or artifacts that could tell us moreabout life in the desert before it dried out.
