A small bit of human jawbone found in Israel has been dated to between 177,000 and 194,000 years ago. Before this discovery, most evidence suggested Homo sapiens hadn't left the African continent until 122,000 years ago.

It's a big deal. The research was published today in Science, and if it holds true, then humanity's story just got a lot more complex. (Our species is believed to have arisen around 315,000 years ago from some common ancestor with the Neanderthal in Africa.)

Location of early modern human fossils in Africa and the Middle East. The fossils from Jebel Irhoud date to315,000 years ago and are thus older than Misliya, while those from Omo Kibish (195,000) and Herto(160,000) are similar in age to Misliya (177,000-194,000). Rolf Quam, Binghamton University

Besides the skull fragment, the Misliya Cave site in Israel also contained a series of tools associated with the Levallois technique—a stone toolmaking common to early humans. We asked Israel Hershkovitz at Tel Aviv University why the discovery was important and how it puts our own origins in context.

Our Species May Be Much Older Than We Think



This skull fragment is older than any previously found outside of Africa, and that's not all. It also has more modern features than those associated with East African sapiens fossils. This might place our species something closer to 500,000 years old. "The history of our own species—Homo sapiens—is longer and probably more complicated than scientists had previously believed," Hershkovitz says.

We Can Tell Because of the Teeth

Virtual reconstruction of the left upper jaw of Misliya-1. The right (transparent) side is a mirror image of the preserved left side for visualization purposes. The dental arch is parabolic and the alignment of the anterior teeth appears very modern human like Gerhard Weber, University of Vienna

The jawbone fragment comes from the left portion of the upper jaw. The incisors and canines have features that occur only in Homo sapiens and not in our close cousin species, the Neanderthal and the Denisovan hominid. In particular, the teeth in this sample lack what's called "shoveling," which is a "thickening of the tooth crown along the edges of the inside surface of the incisor and canine." It also lacks several features commonly seen in Neanderthals, including a "cusp at the base of the tooth crown."

According to Hershkovitz, these features make this find the oldest known anatomically modern humans (compared to more primitive Homo sapiens fossils found in Africa that retain archaic characteristics).



We Might Know Where These Humans Went

In 2015, fossils of anatomically modern humans were found in China that dated to as much as 120,000 years old. That's about when we'd assumed humans were just leaving Africa. Interestingly, there's a connection between the newly announced fragment (which, remember, is 177,000 years old or older) and the Chinese fossils.

A view of Misliya Cave when approached climbing from the coastal plain. The cave is located some 90 mabove mean sea level (AMSL) and is part of a series of prominent prehistoric cave sites located along thewestern slopes of Mount Carmel, Israel. Mina Weinstein-Evron, Haifa University

There have been rival schools of thought as to how early humans migrated, especially in light of the Chinese fossils. In one scenario, humans migrated from modern day Ethiopia into Israel and then on to East Asia. In the other scenario, humans crossed over through the Arabian peninsula, into India, and up through East Asia.

As these fossils were found in modern day Israel, and have similar features to those seen in the Asian fossils, it suggests that the northern migration is the more likely scenario. "The new fossils recently discovered in China suggest that they had moved on to Southeast Asia," Hershkovitz says.

The Tools Served a Variety of Purposes

The wear on the tools shows they were used mostly for cutting and scraping plant materials. However, others were used to treat hides from deer and other similar animals in the area, or for flaking rocks to make other tools.



This May Mean Humans and Neanderthals Intermingled

As fossil evidence has accumulated, a new picture of human history has been painted: we shared the Earth with at least four different human relatives, including the Neanderthals, the Denisovans (an Asian relative of the Neanderthals), Homo erectus, and the diminutive and regionally isolated Homo floresiensis. DNA evidence shows interbreeding with the Neanderthals and the Denisovans, and the Denisovans likely mated with an ancient human ancestor—possibly Homo erectus, though its DNA has never been sequenced.

Israel Hershkovitz

Neanderthals were known to be in this area at the time. Hershkovitz says, "we think that modern humans interbred with the Neanderthals much earlier than previously thought" if the dating on these fossils is correct.

But "anatomically modern" people may have been a result of interbreeding with several human cousin species known to be living alongside modern humans. "This new discovery from Misliya Cave opens the door to demographic replacement or genetic admixture between modern humans and other local populations much earlier than previously thought," he says.

By Discovering Their Tools, We Have an Insight Into Their Lives

Hershkovitz says some African specimens have been "accidental finds" that unearthed only the fossils themselves. By finding tools in the region, we have a better idea of how the Misliya people lived. "This allowed us a glance into the lifestyle of our remote ancestors," he says.

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