Ancient Homo species left primitive cutting implements far beyond East Africa
Ancient stone-tool makers spread into largely unstudied parts of North Africa and the Arabian Peninsula surprisingly early, two new studies find. Discoveries in Algeria and Saudi Arabia underscore how toolmaking traditions enabled Stone Age Homo groups to travel long distances and adapt to different environments, researchers say.
Hominids used simple cutting and chopping implements to remove meat from animal carcasses in North Africa around 2.4 million years ago, archaeologist Mohamed Sahnouni and colleagues report online November 29 in Science. That’s roughly 200,000 years after the first known appearance of such tools in East Africa. Early members of the human genus, Homo, either continued to make these tools after moving from East Africa or independently created similar tools in East and North Africa, the scientists conclude.
Earlier excavations at two other Algerian sites, also conducted by Sahnouni’s team, had uncovered stone tools and evidence of animal butchery dating back no more than 1.8 million years.
No hominid fossils have been found at any of the North African locations. But the discovery of stone tools strewn among butchered animal remains at Algeria’s Ain Boucherit site adds to evidence that Homo evolution didn’t just occur in East Africa (SN: 12/23/17, p. 24). “Our ancestors ventured into all corners of Africa,” says Sahnouni, of the National Research Center for Human Evolution in Burgos, Spain.
Discoveries at Ain Boucherit “show that the North African savanna corridor and the East African one were connected and early [Homo] started using stone tools and eating meat basically simultaneously in both areas,” says archaeologist Manuel Domínguez-Rodrigo of Complutense University in Madrid who was not part of the research team.
Sahnouni’s group excavated stone tools and animal bones from two sediment layers at Ain Boucherit. After initial finds in 2006 and 2008, fieldwork from 2009 through 2016 produced a total of 17 stone artifacts from a lower, older sediment layer and 236 similar specimens from an upper sediment layer. Lower and upper layers also contained 296 and 277 fossil animal bones, respectively.
Identification of previously dated reversals of Earth’s magnetic field recorded in the soil and estimates of the time since sediment had been buried provided ages of around 2.4 million years for the lower layer and about 1.9 million years for the upper layer.
Fossil bones found among stone artifacts at Ain Boucherit came from savanna-dwelling animals such as elephants, horses, rhinos, antelopes and crocodiles. Incisions typical of butchery appeared on 17 bones from the lower sediment layer and two bones from the upper layer. These marks were mainly made on limb bones, ribs and skulls, suggesting activities such as skinning and removing flesh. Another four bones from the lower layer and seven from the upper layer displayed hammering and smashing marks, probably as a result of marrow removal.
Ain Boucherit hominids acquired prime parts of game either by hunting or by scavenging at fresh kill sites, Sahnouni suspects.
“The Ain Boucherit evidence could be pointing at some kind of confrontational scavenging where [hominids] were stealing kills from carnivores before carcasses were fully defleshed,” says archaeologist Ignacio de la Torre of University College London who did not participate in the study. That tactic appears most likely, he holds, since evidence of hunting in Africa around the time hominids wielded meat-cutting tools in Algeria is scant.
Long after North Africans sliced up carcasses, a different form of toolmaking headed in another unexpected direction. An African toolmaking style going back nearly 1.8 million years (SN: 10/8/11, p. 12), which included teardrop-shaped hand axes, appeared in the center of the Arabian Peninsula around 240,000 to 190,000 years ago, researchers report November 29 in Scientific Reports.
Evidence that an ancient African toolmaking style reached the Arabian Peninsula as early as 240,000 years ago includes these shaped and sharpened stone hand axes.
Archaeologist Eleanor Scerri of the Max Planck Institute for the Science of Human History in Jena, Germany, and colleagues recovered more than 500 stone artifacts at a site in central Saudi Arabia called Saffaqah. Stone artifacts included large sharp-edged flakes, blocks of stone with depressions where flakes had been pounded off and hand axes. Calculations of the time since sediment was buried provided an age range for the Saffaqah finds. Excavations by another group in the 1980s had unearthed nearly 8,400 hand axes and related implements that have not been dated or analyzed in detail.
Previous evidence, including stone tools, had suggested that the Homo genus reached a grassy, vegetated Arabia at least 300,000 years ago (SN: 11/24/18, p. 16), although the range of tools made by those ancient colonizers is unclear. Scerri and her colleagues suspect that a humanlike species already living in Eurasia, such as Homo heidelbergensis or Homo erectus, first reached central Arabia and managed to cope with increasingly cold, dry conditions. Starting around 240,000 years ago, rainy conditions allowed East African hominids to spread into the Middle East and Arabia along networks of rivers and lakes, Scerri suspects.
M. Sahnouni et al. 1.9-million and 2.4-million-year-old artifacts and stone tool-cutmarked bones from Ain Boucherit, Algeria. Science. Published online November 29, 2018. doi:10.1126/science.aau0008.
E. Scerri et al. The expansion of later Acheulean hominins into the Arabian Peninsula. Scientific Reports. Published online November 29, 2018. doi:10.1038/s41598-018-35242-5.
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