Where's the Beef? Early Humans Took It

[ramonmercado]

Getting to the top of the food chain.

Where's the Beef? Early Humans Took It
http://news.sciencemag.org/sciencenow/2 ... tml?ref=hp
by Ann Gibbons on 23 April 2012, 5:30 PM

Cool cats. The skull and jaw of two different species of extinct saber-toothed cats, which lived during the heyday of carnivores 3 million to 3.5 million years ago in the Turkana Basin of Kenya.
Credit: Lars Werdelin/© National Museums of Kenya

PALISADES, NEW YORK—When human ancestors began scavenging for meat regularly on the open plains of Africa about 2.5 million years ago, they apparently took more than their fair share of flesh. Within a million years, most of the large carnivores in the region—from saber-toothed cats to bear-size otters—had gone extinct, leaving just a few "hypercarnivores" alive, according to a study presented here last week at a workshop on climate change and human evolution at Columbia University's Lamont-Doherty Earth Observatory.

Humans have driven thousands of species extinct over the millennia, ranging from moas—giant, flightless birds that lived in New Zealand—to most lemurs in Madagascar. But just when we began to have such a major impact is less clear. Researchers have long known that many African carnivores died out by 1.5 million years ago, and they blamed our ancestor, Homo erectus, for overhunting with its new stone tools. But few scientists thought there were enough hominins—ancestors of humans but not other apes—before that to threaten the fierce assortment of carnivores that roamed Africa, or that the crude stone tools that our ancestors began to wield 2.6 million years ago could be used for hunting. Besides, it was probably much more dangerous for the puny hominins alive then, such as Australopithecus afarensis, whose brain and body were only a bit bigger than a chimp's, to grab carcasses than it was for supersized carnivores such as giant hyenas, cats, and otters to devour hominins. "One of my favorite images is of an Au. afarensis being dragged down by a giant otter," says vertebrate paleontologist Lars Werdelin at the Swedish Museum of Natural History in Stockholm.

Werdelin decided to investigate to discover when the decline began and what types of species went extinct by analyzing the jaws, teeth, snouts, and other anatomy of large and small carnivores. These features reflect the breadth of the animals' diets and the niche they occupied in the community of carnivores—an approach known as community ecology analysis. For example, many meat eaters have teeth that are specialized cutting blades, whereas omnivores that also eat fruit have crushing teeth. After comparing fossils of 78 species of carnivores that lived during five different periods of time between 3.5 million years ago (when large carnivores were at their peak) and 1.5 million years ago, Werdelin found that all but six of 29 species of large carnivores (animals that weighed more than 21.5 kilos) had gone extinct in that time. Moreover, the mass extinction began just before H. erectus appeared in the fossil record 1.9 million years ago. He also found that the community of carnivores alive 2.5 million to 2 million years ago ate a much broader range of food—with species within a community filling a wider range of dietary niches. By 1.5 million years ago, just hypercarnivores that ate only meat, such as lions and leopards, had survived while omnivores that scavenged and ate a wider range of foods, like civets, had disappeared. "Even I was surprised by the dramatic drop," Werdelin says.

Those omnivores that went extinct were in direct competition for scavenged carcasses with hominins. Perhaps hominins could scare away the relatively small civets, for example, by working in groups and throwing stones at them, says Werdelin. The results also suggest that humans were already "great at messing with the environment" by disrupting the wildlife, says Werdelin.

"Lars has applied novel methods of community ecology analysis to the problem, and that's an excellent advance," says paleoanthropologist Richard Potts of the Smithsonian's National Museum of Natural History in Washington, D.C. As a result, he says, "We are coming to a better understanding of how our species has modified the planet."

 

[EnolaGaia]

Anthropologist finds evidence of hominin meat eating 1.5 million years ago

Eating meat may have 'made us human'

DENVER (Oct. 4, 2012) – A skull fragment unearthed by anthropologists in Tanzania shows that our ancient ancestors were eating meat at least 1.5 million years ago, shedding new light into the evolution of human physiology and brain development.

"Meat eating has always been considered one of the things that made us human, with the protein contributing to the growth of our brains," said Charles Musiba, Ph.D., associate professor of anthropology at the University of Colorado Denver, who helped make the discovery. "Our work shows that 1.5 million years ago we were not opportunistic meat eaters, we were actively hunting and eating meat."

The study was published Wednesday in the peer-reviewed journal PLOS ONE.

The two-inch skull fragment was found at the famed Olduvai Gorge in northern Tanzania, a site that for decades has yielded numerous clues into the evolution of modern humans and is sometimes called `the cradle of mankind.'

The fragment belonged to a 2-year-old child and showed signs of porotic hyperostosis associated with anemia. According to the study, the condition was likely caused by a diet suddenly lacking in meat.

"The presence of anemia-induced porotic hyperostosis…indicates indirectly that by at least the early Pleistocene meat had become so essential to proper hominin functioning that its paucity or lack led to deleterious pathological conditions," the study said. "Because fossils of very young hominin children are so rare in the early Pleistocene fossil record of East Africa, the occurrence of porotic hyperostosis in one…suggests we have only scratched the surface in our understanding of nutrition and health in ancestral populations of the deep past."

Musiba said the evidence showed that the juvenile's diet was deficient in vitamin B12 and B9. Meat seems to have been cut off during the weaning process.

"He was not getting the proper nutrients and probably died of malnutrition," he said.

The study offers insights into the evolution of hominins including Homo sapiens. Musiba said the movement from a scavenger, largely plant-eating lifestyle to a meat-eating one may have provided the protein needed to grow our brains and give us an evolutionary boost.

Some scientists have argued that we became human when we became carnivorous-omnivorous creatures.

"Meat eating is associated with brain development," he said. "The brain is a large organ and requires a lot of energy. We are beginning to think more about the relationship between brain expansion and a high protein diet."

Humans are one of the few surviving species with such a large brain to body size ratio. Chimpanzees, our closest relatives, eat little meat and have far less brain capacity than humans, Musiba said.

"That separates us from our distant cousins," he said. "The question is what triggered our meat eating? Was it a changing environment? Was it the expansion of the brain itself? We don't really know."

Four students participating in the CU Denver Tanzania Field School were at Olduvai Gorge when the skull fragment was discovered.

"It was a great experience for them," said Musiba, director of the Field School and a native of Tanzania. "Hopefully, it will inspire even more students to come to Africa and help us find answers to the questions posed by these discoveries."

SOURCE: http://www.eurekalert.org/pub_releases/ ... 100312.php