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Moroccan fossils show Human ancestors’ diet of game

New fossil finds from the Jebel Irhoud archaeological site in Morocco do more than push back the origins of our species by 100,000 years. They also reveal what was on the menu for our oldest-known Homo sapiens ancestors 300,000 years ago: Plenty of gazelle meat, with the occasional wildebeest, zebra and other game and perhaps the seasonal ostrich egg, says Teresa Steele, a paleoanthropologist at the University of California, Davis, who analyzed animal fossils at Jebel Irhoud.

Moroccan fossils show Human ancestors’ diet of game
The mandible Irhoud 11 is the first, almost complete adult mandible discovered at the site of Jebel Irhoud. It is very robust 
and reminiscent of the smaller Tabun C2 mandible discovered in Israel in a much younger deposit. The bone morphology 
and the dentition display a mosaic of archaic and evolved features, clearly assigning it to the root of our own lineage 
[Credit: Jean-Jacques Hublin, MPI-EVA, Leipzig]
Steele, who studies how food sources and environmental change influenced human evolution and migration, was part of the international research team that began excavating at the site in 2004. She is the co-author of one of two papers featured in Nature: "Human origins: Moroccan remains push back date for the emergence of Homo sapiens."

Jebel Irhoud has been well known since the 1960s for its human fossils and for its Middle Stone Age artifacts, but the geological age of those fossils was uncertain.

Moroccan fossils show Human ancestors’ diet of game
View looking south of the Jebel Irhoud site in Morocco. The remaining deposits and several people excavating them 
are visible in the center. At the time the site was occupied by early hominins, it would have been a cave, 
but the covering rock and much sediment were removed by work at the site in the 1960s 
[Credit: Shannon McPherron, Max Planck Institute for Evolutionary Anthropology]
The new excavation project -- led by Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and Abdelouahed Ben-Ncer of the National Institute for Archaeology and Heritage (INSAP) in Rabat, Morocco -- uncovered 16 new Homo sapiens fossils along with stone tools and animal bones. The remains comprise skulls, teeth, and long bones of at least 5 individuals.

Thermoluminescence dating of heated flints yielded an age of approximately 300,000 years ago -- 100,000 years earlier than the previously oldest Homo sapiens fossils.

Moroccan fossils show Human ancestors’ diet of game
Two of the newly discovered fossils in situ. In the center of the image, in a slightly more yellow brown tone, is the crushed 
top of a human skull (Irhoud 10) and visible just above this is a partial femur (Irhoud 13) resting against the back wall 
[Credit: Steffen Schatz, Max Planck Institute for Evolutionary Anthropology]
Analysis of the animal fossils provided additional evidence to support the date. Dating of rodent remains suggested they were 337,000 to 374,000 years old.

Steele sifted through hundreds of fossil bones and shells, identifying 472 of them to species as well as recording cut marks and breaks indicating which ones had been food for humans.

Moroccan fossils show Human ancestors’ diet of game
Jaw bone of a gazelle from Jebel Irhoud, Morocco. The site contains the oldest-known skeletons of modern humans.
 UC Davis anthropologist Teresa Steele studied animal bones from the site, showing that our ancestors ate lots
 of gazelle and other game as well as ostrich eggs [Credit: Teresa Steele/UC Davis]
Most of the animal bones came from gazelles. Among the other remains, Steele also identified hartebeests, wildebeests, zebras, buffalos, porcupines, hares, tortoises, freshwater molluscs, snakes and ostrich egg shells.

Small game was a small percentage of the remains. "It really seemed like people were fond of hunting," she said.

Moroccan fossils show Human ancestors’ diet of game
Nicks on the edge of this piece of bone show that it was used to retouch the edge of a stone tool 
by gently striking against it [Credit: Teresa Steele/UC Davis]
Cuts and breaks on long bones indicate that humans broke them open, likely to eat the marrow, she said. Leopard, hyena and other predators' fossils were among the finds, but Steele found little evidence that the nonhuman predators had gnawed on the gazelle and other prey.

Steele said the findings support the idea that Middle Stone Age began just over 300,000 years ago, and that important changes in modern human biology and behaviour were taking place across most of Africa then.

"In my view, what it does is to continue to make it more feasible that North Africa had a role to play in the evolution of modern humans."

Author: Kathleen Holden | Source: University of California - Davis [June 07, 2017]

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1 comment :

  1. The arch in the jawbone is incredible, very derived and evolved. Nowhere near the neander/sapiens common ancestor. If this fossil is 310,000, and more likely 340,000 then Sapiens must be 550,000 y/o. The refinement of this mandible pushes dates way, way back. In agreement w/genetic and molecular dates.


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