Evrim Yazgin
Cosmos science journalist
A new geological dating technique might just have settled one of the longest running debates on human evolution and expansion – when and where did the first hominids arrive in Europe?
Hominids are the group of primates which includes modern humans, chimpanzees, gorillas, and orangutans plus all their immediate ancestors.
Sites at in the Baza basin in Granada have yielded ancient human remains since at least the 1980s. A new study, published in the Earth-Science Reviews journal, provides evidence that these are the earliest known hominids to have made it to Europe.
Finding the oldest evidence of hominids on the Iberian Peninsula suggests they first expanded out of Africa into Europe via the Strait of Gibraltar to the west, not via the Asian route to the east.
New geological dating analysis is reported in the study which tests the rocks from the site in the Orce municipality of southern Spain.
The technique is based on palaeomagnetism – the record in rocks of the direction of Earth’s magnetic field which has flipped at least 183 times in the last 83 million years, or every 450,000 years on average. While there is no specific periodicity to the flips, the record of the swapping of the magnetic poles can be used to establish time periods from different magnetic events.
Researchers were able to identify 5 magnetic events which helped place 3 Orce sites with human presence between 1.77 and 1.07 million years ago.
They were then able to narrow down the timeframe to a margin of error of 70,000 years.
According to the researchers, the 3 human sites had ages of 1.23, 1.28 and 1.32 million years respectively.
And there is further evidence at the Orce sites found by the researchers which points to these early European hominids coming directly from Africa, rather than via Asia. This includes stone tools similar to those found in northern Africa and animals like hippopotamus and primates related to those in Africa and not found anywhere else in Europe.
These animals, the researchers suggest, crossed the Strait of Gibraltar between 6.2 and 5.5 million years ago.
“We also defend the hypothesis that they arrived from Gibraltar because no older evidence has been found at any other site along the alternative route,” says Lluís Gibert, lead researcher and a lecturer at the University of Barcelona in Spain.
This is despite a study earlier this year which suggests the oldest hand tools found in Europe were uncovered in Ukraine and dated to about 1.42 million years old. The authors of the new study write that “this chronology is supplied at 68% of confidence interval and should be taken with caution until additional dating is done.”
This compares to the 95% confidence interval of the dating of the Orce sites.
The researchers note that their results suggest hominids left Africa for Europe about half a million years after they arrived in Asia where the oldest evidence for human occupation dates to about 1.8 million years ago.
“These differences in human expansion can be explained by the fact that Europe is isolated from Asia and Africa by biogeographical barriers that are difficult to overcome, both to the east (Bosphorus Strait, Dardanelles, Sea of Marmara) and to the west (Strait of Gibraltar).
“Humanity arrived in Europe when it had the necessary technology to cross maritime barriers, as happened a million years ago on the island of Flores (Indonesia),” says Gibert.
