Why our common ancestor with chimpanzees keeps getting further away — SkimNews
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- João d'Oliveira Coelho, a biological anthropologist at Gorongosa National Park in Mozambique, published a meta-analysis in the journal Primates on June 18 synthesizing 202 estimates of the human-chimp split from the late 1960s through the 2020s.
- The study found the average estimated split has moved from about 6 million years ago in early studies to roughly 8.5 million years in recent ones — meaning humans and chimps have been evolving separately for 2.5 million years longer than once thought.
- D'Oliveira Coelho's own team placed the split between 8.69 million and 7.28 million years ago, though he emphasized that won't be the final word and that claims of a really recent split can be ruled out.
- Improved chimp genome data has driven much of the revision: the first draft arrived in 2005, with a much more complete version roughly 20 years later that filled in missing pieces and corrected errors.
- Discoveries of key early hominin fossils also forced the revision — Orrorin and the oldest Ardipithecus were described in 2001, with Sahelanthropus following in 2002 at about 7 million years old, yet it wasn't until around 2015 that average genetic estimates became older than that date.
- D'Oliveira Coelho blamed the lag on poor communication between physical anthropologists and geneticists, and on geneticists being "overconfident" about their data and methods.
Why it matters: By synthesizing 202 estimates, the study gives paleoanthropologists a tighter anchor — a split closer to 8.5 million years ago — that should prevent geneticists from drifting back toward the obsolete 4-million-year figure still found in some recent textbooks alongside hominin fossils that contradict it. The 7-million-year-old Sahelanthropus, Orrorin and Ardipithecus now sit firmly inside the divergence window rather than floating above it.
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