UNH geologist Will Clyde—holding a rock sample from the site of the discovery—used geomagnetic dating to determine the age of new fossils that shed light on humanity's ancient ancestors.

Geologist Dates New Fossils of Ancient Human Ancestors

By Robert Emro, CEPS

When paleontologists discovered the fossilized remains of two previously unknown species of primate in Egypt, they turned to a University of New Hampshire geologist to help date their find.

UNH Associate Professor Will Clyde put the age of the fossils at around 37 million years, making them some of the oldest human ancestors ever found. The findings are published in the latest issue of the journal Science in a paper by lead author Erik Seiffert, of the University of Oxford.

Only in the last decade have scientists suspected the true age of humanity's predecessors, called anthropoid primates. “When I was in graduate school, there wasn’t even talk of anthropoids being of this age,” said Clyde. “These fossils are filling in a gap in our understanding of anthropoid evolution.”

One of the fossils, a piece of upper jaw and part of a large eye socket, suggests that one of the new species was nocturnal, a unique trait among early anthropoids. This evidence that anthropoids had evolved such diversity in Africa as early as 37 million years ago lends support to the theory that our anthropoid ancestors originated there. Some anthropologists, however, have argued anthropoids originated in Asia, based on even older fossil finds from Pakistan, Myanmar, China and Thailand.

While his findings are sure to be embraced by those on the Africa side of the debate, Clyde is reserving judgment. “There’s not enough evidence to say one way or the other yet,” he said.

Clyde used geomagnetic dating to determine the age of the fossils. The technique relies on reversals in the Earth’s magnetic field, which occur with irregular frequency every several hundred thousand years. By matching the pattern of reversals in the rock around the fossils with the known pattern of reversals obtained from lava deposited on the seafloor by the mid-ocean ridge, he was able to establish an approximate age.

“You can think of it as a master bar code on the ocean floor. You get a little piece of the bar code from where you are working and hopefully the pattern is unique enough that you can match it up,” explained Clyde. “Of course, we have some idea of where in time we are so what this really does is allow us to nail it down more precisely.”