Jawbone Fossil Found in Israeli Cave Resets Clock for Modern Human Evolution

Amanda Borschel, Times of Israel, January 25, 2018

A jawbone found in a cave in Israel’s Mount Carmel region has reset the clock on human evolution.

The fossil, the earliest known record of Homo sapiens outside of Africa, was discovered in 2002 during an excavation of the prehistoric Misliya Cave. After 15 years of intensive research by an international team of multidisciplinary scientists, the unique remains of an adult upper jawbone, complete with several teeth, has been dated to 170,000-200,000 years ago.

“This has changed the whole concept of modern human evolution,” said Prof. Israel Hershkovitz of the Department of Anatomy and Anthropology at Tel Aviv University’s Sackler Faculty of Medicine. The research was published Thursday in the prestigious Science magazine.

Based on fossils found in Ethiopia, for the past 50 years scientists have believed that modern humans appeared in Africa, the “cradle of humanity,” roughly 160,000-200,000 years ago. The earliest record of migration outside of Africa was dated to around 90,000-120,000 years ago, through fossils discovered at digs in Israel’s Skhul and Qafzeh caves almost 90 years ago.

With this Misliya cave jawbone, however, the history of human evolution is being rewritten.

“The entire narrative of the evolution of Homo sapiens must be pushed back by at least 100,000-200,000 years,” said Hershkovitz, the head of the Dan David Center for Human Evolution and Biohistory Research at TAU’s Steinhardt Museum of Natural History.

The Misliya fossil not only resets the date for Homo sapien evolution and migration, but also spurs the mind-blowing implication that modern humanity did not evolve independently but rather alongside — and intermingled with — many other hominin groups, such as Neanderthals, he said.

The dating of a modern human fossil to 200,000 years ago “implies that the biological history of our species must be pushed back to half a million years ago,” Hershkovitz told The Times of Israel on Thursday. “It implies that our species didn’t evolve in isolation… The species was involved with a very long interaction with other groups.”

“Our species,” said Hershkovitz, “is a genetic mishmash of several hominins.”

Archaeological findings from the cave support this “mishmash” theory by providing an even earlier sedimentary-layered context for modern human settlement — by about 50,000 years. Therefore, modern human settlement in Israel could arguably be dated to even 250,000 years ago.

According to University of Haifa archaeologist Prof. Mina Weinstein-Evron of the Zinman Institute of Archaeology, “Miss Lia,” as she fancifully calls the fossil from the Misliya site, was discovered in a layer well after the indications of first modern human settlement there. (There is no way to ascertain the gender of the fossil.)

Speaking with The Times of Israel just hours after the press announcement of the revolutionary find, Weinstein-Evron reminisced that when she and Hershkovitz first drew up plans ahead of commencing the joint dig in 2001, their stated (modest) goal was to look for the origins of the modern Homo sapiens. With the discovery of “Miss Lia” in the Mount Carmel region, which is rife with indications of paleolithic settlement, she said, “we have found something even more surprising.”

During 10 years of excavations, along with the jawbone, the team uncovered some 60,000 flint tools, which span the human history of development from chunky primitive hand axes to purposefully knapped, lightweight, technologically advanced projectiles and thin knives.

During artifact analysis, researchers were able to discern the different lingering flora and fauna on the tools.

“The new zooarchaeological data from Misliya Cave, particularly the abundance of meat-bearing limb bones displaying filleting cut marks and the acquisition of prime-age prey, demonstrate that early Middle Paleolithic people possessed developed hunting capabilities. Thus, modern large-game hunting, carcass transport, and meat-processing behaviors were already established in the Levant in the early Middle Paleolithic, more than 200,000 years ago,” according to a 2007 Journal of Human Evolution study from the dig.

“They had a delicatessen in the cave,” said Weinstein-Evron, who listed auroch and other deer steaks, hares, ostrich eggs and wild boars as among the foodstuffs found in the caves. “They supped on ham and eggs,” she joked.

Likewise, said Weinstein-Evron, the team discovered the world’s first signs of the use of organic padding for the settlers’ seats next to the communal hearth.

In addition to the genetic analysis of the bone, archaeological findings confirmed that Homo sapiens “lived in parallel with other types of humans a lot longer than thought,” she said. Fossil records have indicated that Homo sapiens are a very diverse group. Now, she said, it is much more likely that the species is made up of a mix of hominin groups.

“We are researchers, not ‘finders,’” said Weinstein-Evron. “The minute we uncover one thing, it is the beginning of looking into something else.”

Dating and typifying the fossil took 15 years and a team of inter-disciplinary international scientists who together confirmed the groundbreaking fossil’s properties and its dating to circa 170,000 to 200,000.

Back in 2002, the jawbone fossil was discovered in “petrified soil,” said Hershkovitz. It was removed as a block out of the cave and taken to the laboratory, where the year-long process of sediment removal commenced.

“It is a frustrating process that takes a lot of time. It must be done step by step in order not to damage the fossil. It took about a year just to clean and prepare it for study,” he said.

Next, the fossil’s dating began. “This is the critical issue, we had to be absolutely sure,” he said, so it was decided to use the next several years to implement several different methods to date the bone, as well as sediment from the excavation site.

“It takes years, working almost day by day on the specimen,” he said. Some of the dating processes are time dependent, explained Hershkovitz, such as a radiation dating technique which requires a year.

The team, he said, had no idea about how old the jawbone would turn out to be. “The first thing that caught our eyes was that the layer we were excavating was from the early middle paleolithic period, which in Israel is 250,000 to 140,000. So we were quite sure the specimen was older than 120,000,” the oldest known Homo sapien fossil outside of Africa until that time.

The dating completed, he said, “we had to prove that the specimen belongs to our species, Homo sapiens.” To that end, the bone was scanned for 3D analysis.

Tel Aviv University’s Dr. Rachel Sarig participated in the analysis. “In the Misliya specimen we used the most advanced methods, using micro CT analysis, which actually allowed us to dig into the tooth, to virtually peel the layers of the bone and other teeth, we could look into the tooth into the dentin layer and analyze the shape of the dentin of the roots of the tooth and of the enamel crown.”

Sarig said the specimen displays “modern characteristics.” “It has more modern features which are similar to modern populations than to other ancient populations such as the Neanderthals,” said Sarig.

According to Tel Aviv University’s Dr. Hila May, there are five features that indicate the maxilla jawbone is of the Homo sapien species. These include the small parabolic dental arch, the location of the incisive foramen, where the anterior part (zygomatic arch) enters to the maxilla, the ridge where the anterior part of the zygomatic arch enters to the maxilla, and the orientation of the floor of the nasal cavity, May enumerated in a video put out by Tel Aviv University.

In the video, Weinstein-Evron sits at a table in front of an array of tools which were discovered in the cave. She pointed out the rugged, large hand axes, then the lighter, more precise and sophisticated flint tools, a clear visual representation of the evolution of the human species.

“We found evidence for everything in the cave… And from Mount Carmel, apparently these modern humans with their industry, colonized slowly and slowly, all of the old world,” said Weinstein-Evron.

As to who these early modern humans were and what they were capable of, Hershkovitz said, is impossible to know based purely on this upper jawbone.

“But judging from the sophistication of their tools, which were formed using a very unique technique, that attests to their intellectual capabilities. I personally believe they were as smart as we are today, but that’s just a guess,” said Hershkovitz

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