The first anatomically modern humans arose in Africa but through a series of complex migrations they came to live throughout Europe and Asia as well. There’s also evidence of a migration back into Africa. These migrations are not well understood though as DNA is very fragile and easily degrades in the hot African climate. Because of this, ancient DNA (also known as aDNA) has never been extracted from bones of an early African human though.
But this has changed though with the first ever extraction and sequencing of DNA from an ancient human living in Africa. In a study published Thursday in the journal Science, scientists revealed they have sequenced the genome of an ancient man that lived in modern day Ethiopia about 4,500 years ago. The man has been called Mota, named after the cave the remains were found in.
By comparing Mota’s DNA with that of people living in Africa today, researchers found evidence of a back migration from Europe and Asia to Africa that occurred about 3,000 years ago. When the back migration occurred, early Eurasians and Africans bred and their genes were mixed. Evidence of this can be seen in the DNA of todays Africans. But the Mota genome didn’t contain any of the European DNA because he lived about 1,500 years before the migration. This is strong evidence of a back migration. What caused the migration of the Eurasians, who were Neolithic farmers, is unknown.
This migration back into Africa has certainly left its mark; 20% of the genome of Africans living in Ethiopia is of Eurasian origin. Furthermore 5-6% of DNA of people in some other African countries also comes from these Neolithic farmers.
The bone that provided the DNA was a petrous bone, which is located just below the ear. This small bone is very hard and can protect DNA better than most bones. The hot and humid climate in Africa normally makes it very difficult for DNA to remain intact.
“We have the complete blueprint, every single gene, every single bit of information that made this individual that lived 4,500 years ago in Ethiopia,” said Dr. Andrea Manica, who was one of the scientists who published the study.
This discovery is the just the beginning of understanding the complex migration patterns of early humans. Hopefully more samples of DNA can be extracted from other bones and give us a more clear idea of how humans got to where they are today.