An international group of Israeli and American researchers has discovered a vertebra from a hominin species dated to 1.5 million years ago that lived in the Jordan Valley. The bone was from a child aged 6-12 and is the most ancient evidence of a human presence in today’s Israel, as well as the second oldest human remain found outside of Africa.
The stunning find shines light on the most ancient human migrations out of Africa by offering a sign that multiple waves of different hominin species left the continent, the researchers said in an article published Wednesday in the prestigious peer-reviewed Scientific Reports journal.
“We now have unambiguous evidence of the presence of two distinct dispersal waves,” said the researchers.
Human evolution can be traced back around 6 million years through fossil and DNA evidence. Hominins are primates that are modern humans’ direct ancestors or closely related to us. Homo sapiens, our modern form, does not appear in the fossil record until around 200,000 to 300,000 years ago.
Evolution is not a straight path, but a tree, with many branches leading nowhere. It occurs on a long continuum and there have been many hominin species that went extinct, the most famous being the Neanderthals. (The famous ancient skeleton dubbed “Lucy,” found in Ethiopia in 1974, was a pre-Homo sapiens hominin from 3.2 million years ago.)
Around 2 million years ago, there is evidence that some archaic human species began to leave Africa. The first human remains of groups that left Africa were found in modern Georgia in the Caucasus region and are dated to around 1.8 million years ago. Archaeologists found their remains and tools at a site called Dmanisi.
The new vertebra found in Israel is evidence of a second wave out of Africa by another species hundreds of thousands of years later, the researchers said.
Archaeologists found the tiny bone in 1966 at a prehistoric site called ‘Ubeidiya, near Kibbutz Beit Zera, just south of the Sea of Galilee. During these previous excavations from 1960 to 1999, archaeologists uncovered ancient stone and flint tools that resemble finds in eastern Africa; extinct animal bones including sabertooth tigers, mammoths and giant buffalo; and bones from species no longer in the region, including baboons, warthogs, hippopotamuses, giraffes and jaguars.
For the new study, researchers renewed excavations at the site and made use of new technology to better classify and date previous finds.
The ancient child’s vertebra was discovered while examining fossils from the previous excavations that are kept at the Hebrew University of Jerusalem. The bone had previously been examined but had not been identified.
They identified it as a human lumbar vertebra, from the lower part of the back, dating to 1.5 million years ago.
The researchers said there is an ongoing debate over whether humans left Africa at once, or in multiple waves, and the new find supports the second theory, since it appeared to be from a different human species than the skeletons in Georgia.
Stone tools found in Georgia and at the Israeli site were also different. Researchers initially believed they were produced by two different cultures, but in the new report, the archaeologists said they were likely made by different species.
The new study also uncovered that the two known sites of early human habitation had divergent climates that contributed to the distinct cultures.
“One of the main questions regarding the human dispersal from Africa were the ecological conditions that may have facilitated the dispersal. Our new finding of different human species in Dmanisi and ‘Ubeidiya is consistent with our finding that climates also differed between the two sites. ‘Ubeidiya is more humid and compatible with a Mediterranean climate, while Dmanisi is drier with savannah habitat,” said Prof. Miriam Belmaker of the University of Tulsa, whose grant facilitated the new excavations.
The Israeli researchers’ analysis showed the bone found in Israel was from an individual who was between 6 and 12 years old at his time of death. He was tall for his age, and would have reached around 5 feet 9 inches tall (180 cm) as an adult.
His size was similar to other large hominins in eastern Africa around the time. The species in Georgia was shorter, the researchers said.
“It seems, then, that in the period known as the Early Pleistocene, we can identify at least two species of early humans outside of Africa,” said Dr. Alon Barash of Bar Ilan University, one of the lead researchers.
“Each wave of migration was that of different kind of humans — in appearance and form, technique and tradition of manufacturing stone tools, and ecological niche in which they lived,” he said.
The study was led by researchers from Bar-Ilan University, Ono Academic College, the University of Tulsa and the Israel Antiquities Authority.