New Fossil Evidence Suggests Early Humans Left Africa 50,000 Years Earlier than Previously Thought

Illustration by Natalie Dye | Staff Illustrator

Jessica Gang

Recent analysis of a remarkably well-preserved jawbone that researchers discovered in Israel reveals that Homo sapiens may have begun their exodus from Africa more than 50,000 years earlier than scientists originally estimated, potentially disproving the popularly accepted “Out of Africa” theory.

A team of researchers who worked in Mount Carmel, Israel published findings in Science magazine on Jan. 25, 2018. The researchers documented the 2002 discovery and subsequent dating that scientists did on the jawbone. While collecting sediment samples from the Mislaya Cave on the western slopes of Mount Carmel, researchers excavated a jawbone with eight teeth still embedded in it.

Alongside the teeth, researchers also uncovered abundant animal remains and evidence of hearths that suggested a rich stone-based industry. A decade of meticulous analyzing and dating the fossil and the surrounding materials place the fossil at approximately 177,000 years old, making it the oldest human fossil found outside of Africa.

Although the jawbone was discovered in 2002, it was not completely dated until 2015, according to the paper published in Science magazine. Researchers were surprised by their initial findings, so they chose to corroborate the results by applying four separate dating methods to the dentin of the teeth, the tooth enamel, sediment attached to the jaw, and remains from the hearth found beside the fossil.

The four separate experiments all yielded consistent results. Thermoluminescence tests — a method for approximating the age of pottery and sediment — revealed flint samples in the hearth area near the jawbone were around 179 (+/- 49) thousand years in age, which helped researchers draw their final conclusions.

If we have modern humans here 200,000 years ago…we have to think about what happened to these people, how they interacted or mated with other species in the area,” said Mina Weinstein-Evron, one of the study’s authors and an archaeologist at the University of Haifa, according to the Smithsonian website. 

The jawbone findings present evidence that seems to conflict with the “Out of Africa” theory of human exodus from Africa, which was developed in the mid 1980s and was widely accepted among scientists until recently. The “Out of Africa” theory states that hominids left Africa in a mass exodus around 60,000 to 70,000 years ago. The theory was authenticated by DNA research by genetically analyzing the descendants of people from Europe, Asia, Australia, and the Americas.

However, there is an increasingly large amount of evidence that supports an earlier origin of our species. Fossils found in June 2017 at the Jebel Irhoud archaeological site in Morocco suggest that modern-looking humans are up to 350,000 years old. Excavations in China also uncovered fragmentary evidence of mating between Neanderthals and Homo sapiens as early as 113,000 years ago.

“It’s not that surprising that [researchers] are going to start seeing [fossils] outside of Africa,” said anthropologist Shara Bailey to the Washington Post. Bailey is a member of the research team that excavated Jebel Irhoud, and she said the amount of evidence supports an early origin. 

But the Mislaya Cave findings bring up more questions than answers, according to Israel Hershkovitz, an anthropologist at Tel Aviv University and the study’s lead author. Hershkovitz hopes to answer these questions: how and why did early hominids travel to Israel? And did the traits that early hominids possessed in the past impact later human evolution?