Thursday, August 09, 2012

Early Meat-Eating Human Ancestors Thrived While Vegetarian Hominin Died Out

Make of this what you will . . . but it seems to support the premise that humans are omnivores. Before the commentary from Katherine Harmon at Scientific American, here is the story form Science Daily.

Early Human Ancestors Had More Variable Diet

ScienceDaily (Aug. 8, 2012) — New research sheds more light on the diet and home ranges of early hominins belonging to three different genera, notably Australopithecus, Paranthropus and Homo -- that were discovered at sites such as Sterkfontein, Swartkrans and Kromdraai in the Cradle of Humankind, about 50 kilometres from Johannesburg. Australopithecus existed before the other two genera evolved about 2 million years ago.

Scientists conducted an analysis of the fossil teeth, indicating that Australopithecus, a predecessor of early Homo, had a more varied diet than early Homo. Its diet was also more variable than the diet of another distant human relative known as Paranthropus.

An international team of researchers, including Professor Francis Thackeray, Director of the Institute for Human Evolution at Wits University, will be publishing their latest research on what our early ancestors ate, online in the journal, Nature, on August 8, 2012. The paper titled 'Evidence for diet but not landscape use in South African early hominins' was authored by Vincent Balter from the Ecole Normale Supérieure in Lyon, France; Jose´ Braga from the Université de Toulouse Paul Sabatier in Toulouse in France; Philippe Te´louk from the Ecole Normale Supérieure in Lyon in France; and Thackeray from the University of the Witwatersrand in Johannesburg in South Africa.

According to Thackeray, the results of the study show that Paranthropus had a primarily herbivorous-like diet, while Homo included a greater consumption of meat.

Signatures of essential chemical elements have been found in trace amounts in the tooth enamel of the three fossils genera, and the results are indicators of what South African hominins ate and what their habitat preferences were.

Strontium and barium levels in organic tissues, including teeth, decrease in animals higher in the food chain. The scientists used a laser ablation device, which allowed them to sample very small quantities of fossil material for analysis. Since the laser beam was pointed along the growth prisms of dental enamel, it was possible to reconstruct the dietary changes for each hominin individual.

Thackeray states that the greater consumption of meat in the diet of early forms of Homo could have contributed to the increase in brain size in this genus.

Australopithecus probably ate both meat and the leaves and fruits of woody plants. The composition of this diet may have varied seasonally.

Apart from the dietary differences, the new results indicate that the home-range area was of similar size for species of the three hominin genera.

The scientists have also measured the strontium isotope composition of dental enamel. Strontium isotope compositions are free of dietary effects but are characteristic of the geological substrate on which the animals lived.

According to the results all the hominids lived in the same general area, not far from the caves where their bones and teeth are found today.

Professor Vincent Balter of the Geological Laboratory of Lyon in France, suggests that up until two millions years ago in South Africa, the Australopithecines were generalists, but gave up their broad niche to Paranthropus and Homo, both being more specialised than their common ancestor.

That is the press release from the University of Witwatersrand - and here is the commentary on that news. I do not agree with Harmon's conclusion, and she repeats the red meat = health problems nonsense (its all in how it's cooked and where it comes from). Even now, children who do not get adequate protein in development are smaller and have lower IQ scores - and there are many other sources of meat than the drug-filled factory cows the meat industry foists on the market.

Early Meat-Eating Human Ancestors Thrived While Vegetarian Hominin Died Out



early human ancestor tooth varied diet
Early Homo molar; image courtesy of Jose Braga/Didier Descouens

There has been fierce debate recently over whether the original “caveman” diet was one of heaps of bloody meat or fields of greens. New findings suggest that some of our early ancestors were actually quite omnivorous. But subsequently, our line and an ill-fated group of hominins developed very different dietary strategies. One chose meat while the other moved toward more plants.

The hominin Australopithecus, which lived from about 4 million to 2 million years ago, is presumed to be a common ancestor of both the Homo lineage, which emerged some 2.3 million years ago and gave rise to us, and to the Paranthropus genius, which is first documented about 2.7 million years ago and died out about 1 million years ago. Some have attributed the extinction of Paranthropus to an inflexible diet or limited territory, especially in the face of climactic changes.

A team of researchers led by Vincent Balter, of École Normale Supérieure de Lyon, decided to probe into some of these debates. They used lasers to analyze the enamel from fossilized teeth belonging to Australopithecus africanus, Paranthropus robustus and early Homo specimens, which were all from southern Africa. By assessing ratios of calcium, barium and strontium as well as the number of strontium isotopes, the team was able to deduce both diet and the size of the area that these individuals ranged over. The findings were published online August 8 in Nature (Scientific American is part of Nature Publishing Group).

The ancestral Australopithecus consumed a wide range of foods, including, meat, leaves and fruits. This varied diet might have been flexible to shift with food availability in different seasons, ensuring that they almost always had something to eat. Paranthropus, according to the elemental analysis, was largely a plant eater, which matches up with previous studies of tooth morphology and wear patterns. It also helps to explain the massive jaw structure they possessed, which could have come in handy for tough food stuffs and earned one specimen the nickname “nutcracker man.” Early Homo, on the other hand, went in for a meat-heavy diet—possibly enabled by the use of tools for hunting and butchering.

However, just because a meatier diet was good for our early Homo forbearers does not necessarily it will keep each of us contemporary humans alive longer. Now that we no longer have to fend for ourselves in quite the same way, increased red meat consumption has actually been linked to shorter individual life spans. So next time you’re flummoxed by food choices, don’t be afraid to go a little Paranthropus and hit the salad bar.

Katherine Harmon 
 About the Author: Katherine Harmon is an associate editor for Scientific American covering health, medicine and life sciences. Follow on Twitter @katherineharmon.
The views expressed are those of the author and are not necessarily those of Scientific American.
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