This year, a study published in Science and led by Tomàs Marquès-Bonet, ICREA researcher at the Institute of Evolutionary Biology (IBE), and the Centro Nacional de Analisis Genomico (CNAG-CRG) revealed novel ancient admixture events among the extant species closest to humans: bonobos and chimpanzees. This study has been then the first study to reveal admixture among the species similar to what has been reported between humans and Neanderthals and shows that admixture might have been a common occurrence during human and primate evolution.
Between 1,5 and 2 million years ago chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) split from a common ancestor and evolved important strong physical and behavioural differences. To this day, the existence of gene flow between the species has not been considered due to the Congo River that physically separates the geographical distribution ranges of the species. The studied samples, comprising 75 complete genomes of chimpanzees and bonobos sequenced at the CNAG-CRG, cover 10 countries in Africa, from the westernmost to the easternmost region of the chimpanzee range. The results have direct application to the conservation of these species because they permit the detection of the origin of chimpanzees confiscated from illegal trafficking. The researchers have found that central and eastern chimpanzees share significantly more genetic material with bonobos than other chimpanzee subspecies do. Thus, it is believed that the admixture between bonobos and chimpanzees occurred during two different episodes: the first one, less than 500,000 years ago and the second one more recently, less than 200,000 years ago.
Compared to our knowledge of the origins and population history of humans, much less is known about the extant species closest to humans, and since many predictions suggest the disappearance of chimpanzees and bonobos within the twenty-first century, this is one of the current efforts to pull together all forces in order to understand and protect the chimpanzees and bonobos before they disappear.