Geneticists at the University of Leicester claim that the genetic Adam of chimpanzees, their ancient common ancestor, lived over one million years ago.
The study, published in the journal Genome Research, states that chimps have a far older lineage compared to humans and other great apes.
The research, funded by Wellcome Trust, involved studying a set of bonobos, chimpanzees, gorillas and orangutans.
The team were able to construct their genealogical trees based on the analyses of the animals’ Y chromosome’s DNA sequence and mitochondrial DNA, which are passed from fathers to sons and mothers to offspring respectively.
Because of two chimps, named Tommy and Moritz, the researchers figured out that chimpanzees’ Adam lived over one million years ago.
Lead author Pille Hallast, from the university’s Department of Genetics, adds that Human ‘Adam’ is about 200,000 years old and gorilla ‘Adam’ is about 100,000 years old.
Lead researcher Mark Jobling notes that this show that ancient humans have practiced a polygonous system, where only selected males can mate with most women while the rest cannot.
Jobling explains this is similar to the mating system observed in gorillas.
“The Y chromosome tree for gorillas is very shallow, which fits with the idea that very few male gorillas (alpha males) father the offspring within groups,” Hallast adds.
“By contrast, the trees in chimpanzees and bonobos are very deep, which fits with the idea that males and females mate with each other more indiscriminately.”
“It’s interesting to compare the shapes of the trees between humans and our great-ape relatives,” Jobling concludes.
“Considering both Y chromosome and mitochondrial DNA trees, humans look much more like gorillas than chimps.”
The researchers plan to study larger samples of great apes in the forest. This will provide clarifications about how their social structure and mating practices affected their diversity.