A new study, published in the journal Earth Science Reviewshelps resolve one of the longest-running controversies in paleoanthropology: when did early hominins arrive in Europe?
Archaic hominins. Image credit: Ninara / CC BY 2.0.
“Chronology of Homo migrations out of Africa have expanded significantly in the last four decades,” said University of Barcelona paleoanthropologist Luis Gibert and his colleagues.
“In 1982, the oldest evidence of Homo in Asia it has been paleomagnetically dated to 0.9 million years ago in Java and 0.7 million years ago in Europe in Italy.
“Forty years later, early chronology Homo beyond Africa it extended to 1.8 million years ago in the southern Caucasus, 1.7–2.1 million years ago in China, and 1.5 to 1.3 million years ago in Java.
“In Europe, several sites occur in layers with meters of reversed paleomagnetic polarity, indicating that they are older than 0.77 million years ago.”
In their research, the authors used magnetostratigraphic dating, a method that uses the status of the Earth’s magnetic field at the time the sediment was deposited, to determine the age of five paleontological localities in the Orce region of Spain.
“This technique is a relative dating method based on the study of the reversal of the planet’s magnetic poles due to the internal dynamics of the Earth,” they explained.
“These changes do not have a specific periodicity, but are recorded in minerals and make it possible to determine time periods from different magnetic events.”
“The peculiarity of these sites is that they are layered and within a very long sedimentary sequence, more than 80 m long,” said Dr. Gibert.
“Normally, the sites are found in caves or within very short stratigraphic sequences, which do not allow you to develop long paleomagnetic sequences in which you can find different magnetic reversals.”
Key date sites showing worldwide distribution of hominins before 1 million years ago (orange color) and possible dispersal routes. The figure shows sites with Oldowan technology (black dots) older than 2 million years in Africa and older than 1 million years in Eurasia. White dots indicate the oldest Acheulian sites in Africa (over 1.5 million years old) and in Eurasia (between 1 and 0.8 million years old). The oldest Oldowan and Acheulian tools are located in East Africa over 2.5 million years ago and over 1.7 million years ago, respectively. In Asia, the oldest Oldowan and Acheulian occur in the Caucasus 1.8 million years ago (7) and in the Levant Corridor 1.2 million years ago (9) respectively. In Europe, the oldest Oldova and related hominins occur in Spain (1, 2) with a debated age of 1.6–0.9 million years. Image credit: Gibert et al., doi: 10.1016/j.earscirev.2024.104855.
Their results show that the oldest Orce sites, which lack evidence of hominin activity, are 1.6 million years old and 1.35 million years old.
Three sites containing evidence of early hominins occur at 1.32 million years ago (Venta Micena), 1.28 million years ago (Barranco León-5), and 1.23 million years ago (Fuente Nueva-3).
These chronologies suggest that the Strait of Gibraltar acted as a filter bridge for African species such as hominins, Theropithecus oswaldiand hippos during the Early Pleistocene.
“This new dating would add to other evidence that would tip the balance in favor of the colonization of Europe via the Strait of Gibraltar, rather than the alternative route: the return to the Mediterranean via Asia,” the scientists said.
“We also support the hypothesis that they arrived from Gibraltar because no older evidence has been found anywhere else along the alternative route.”
“Our results point to a diachronism between the oldest occupation of Asia, at 1.8 million years, and the oldest occupation of Europe, which would be 1.3 million years ago, so African hominids would have arrived in Europe southwest more than 0.5 million years later, leaving Africa for the first time about 2 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 (the Bosphorus Strait, the Dardanelles, the Sea of Marmara) and to the west ( Strait of Gibraltar),” said Dr. Gibert.
“Humanity arrived in Europe when it had the technology needed to cross sea barriers, as happened previously a million years ago on the island of Flores, Indonesia.”
“In this sense, the Gibraltar route currently requires crossing up to 14 km of sea route, but perhaps in the past this distance was shorter at certain times due to the high tectonic activity in this region and the fluctuations in sea level that favored migrations. “
“We identified other migrations of African fauna through Gibraltar at the earliest times, between 6.2 and 5.5 million years ago when the Strait of Gibraltar was very narrow.”
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Louis Guibert et al. Magnetostratigraphic dating of the earliest hominin sites in Europe. Earth Science Reviews, published online July 2, 2024; doi: 10.1016/j.earscirev.2024.104855