Africans carry huge amount of European DNA

The latest study is the first time an ancient human genome has been recovered and sequenced from Africa, the source of all human genetic diversity. Researchers successfully analyzed the complete genetic blueprint of the ancient man’s DNA, thanks to the cooler, drier climate in the cave that preserved the genome. “Now we know that…for every four people there were in East Africa 3,000 years ago, there was one person coming in from West Eurasia”.

Even Africans living today across all parts of the continent can trace at least five percent of their genome to the reverse migration back into Africa from Eurasia.

“While previous studies have documented substantial West Eurasian ancestry in a few sub-Saharan African populations, including Nigerians and KhoeSan from southern Africa, if the findings of this paper are right, they are important because they extend these claims to populations that were previously thought to have little or no West Eurasian ancestry, for example Mbuti hunter gatherers from central/east Africa”. This part of the skill is excellent for the preservation of ancient genome samples. Eurasians remained separate from Africans for nearly 3,000 years before they began coming back to Africa and may have acquired DNA from Europeans.

A comparison with modern populations around the world allowed them to see that the migrants left their genetic mark in the furthest corners of Africa.

The ancient genome predates a mysterious migratory event which occurred roughly 3,000 years ago, known as the “Eurasian backflow”, when people from regions of Western Eurasia such as the Near East and Anatolia suddenly flooded back into the Horn of Africa. But Manica and his colleagues say present day Sardinians, residents of the remote Italian island, are most genetically similar to the ancient farmers of the Near East. A well-preserved skull found in a cave called Mota in the highlands of Ethiopia provided the genetic evidence to prove the so-called “Eurasian backflow” into Africa was much larger in terms of the number of people and lasted longer than previously thought. The crops of wheat and barley in East African are coincided with the arrival of Eurasian migrants. So being able to get a snapshot from before these migration events occurred is a big step.

Dr Manica, speaking to Science in Action on the BBC World Service, said: “The petrous bone is really hard and does a really good job of preventing bacteria getting in and degrading this DNA”.

Commenting on the research, Dr Carles Lalueza-Fox, from the Institute of Evolutionary Biology in Barcelona, Spain, said: “What is nice is that it places in time the origin of the Eurasian backflow into Africa already detected a few years ago from modern genome data, and it turns out to be the farming”.

The study was led by the University of Cambridge but the DNA recovery and sequencing involved researchers based at Trinity College Dublin and University College Dublin. “These new techniques will keep evolving, enabling us to gain an ever-clearer understanding of who our earliest ancestors were”.