Israeli fossil discovery changes evolution timeline

GILLIAN KLAWANSKY

Not only does this make it the oldest human fossil ever found outside of Africa, it also means that modern humans lived outside of Africa up to almost 80 000 years earlier than was previously believed.

As South African Jews, we’re deeply rooted in Africa and Israel. But we’re not the only ones. The very dawn of humanity is believed to have been in Africa, and from there, the first Homo sapiens, aka humans, migrated to the Middle East.

Yet now it seems that this happened much earlier than was originally thought. “Previously, the earliest modern humans found outside of Africa were from Qafzeh and Skhul, caves in Israel, and dated back to about 120 000 years ago,” says Sarah Wurz, associate professor at the archaeology department at Wits University.

So, what does a human jawbone fossil discovery in Israel mean when it comes to current theories about modern human evolution? “Early modern humans were much more widespread outside of Africa at a far earlier date than previously thought, indicating a more complex geographical evolutionary history that includes multiple diffusion events out of Africa,” explains Wurz.

This pushes back the date of the very origins of the human species. Scientists can only speculate as to why the first Homo sapiens may have left Africa. “While it’s not known why populations migrate, one theory is that they follow the migratory prey that’s been hunted,” says Wurz. Seasons are also often associated with such migration.

Clues as to how these humans survived were also found in the cave, in the form of more than 60 000 flint tools ranging from hand axes to more sophisticated small knives – suggesting the evolution of the population’s hunting skills, and perhaps even their intellect.

The jawbone fossil –with eight teeth still embedded  – was discovered in 2002 as part of an excavation project called Searching for the Origins of the Earliest Modern Humans. Yet it took an international team of multidisciplinary scientists almost 16 years to determine its age.

“Dating is a very time-consuming activity, and dating laboratories are involved in many projects that need dates,” explains Wurz. “Ground-breaking studies cannot be published without good dates. In this case, three separate laboratories dated the specimen, because of the importance of the find. This increased confidence in the dating results, and made the publication of the results easier.”

The findings also suggest that modern humanity didn’t evolve in isolation, but rather, alongside and interacting with other hominin groups, such as Neanderthals, reports The Times of Israel.

This is not the first time that experts have had to adjust their evolution clocks. “Theories of human evolution need to change and be updated frequently because of new findings,” explains Wurz. “With the success of DNA analysis, it’s now accepted that there was interbreeding with other groups such as the Neanderthals and Denisovans in the evolutionary history of Homo sapiens.

“Also, it’s very likely that modern humans evolved earlier than 200 000 years ago, and there was thus much more opportunity to migrate from Africa. Recently, 300 000-year-old remains of modern humans were found in Morocco and genetic studies show that the divergence date of early modern humans in southern Africa is also close to this date.”

The jawbone fossil discovery therefore fits in with the timelines suggested by these studies – meaning, the human species is indeed much older than was originally believed. In fact, according to Tel Aviv University paleoanthropologist Israel Hershkovitz, who led the jawbone study, Homo sapiens may even have originated up to 500 000 years ago.

As for the relevance of such findings to our lives today, it’s all about what brings us together as opposed to what draws us apart.

“Findings like these help us to understand our deep evolutionary roots – that we all come from small populations that lived long ago,” says Wurz. “Racial differences are much younger than the first humans. As a species, we are therefore much more alike than we are different.”