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Evolution favoured early meat eaters
Aug 24, 2012

 

One of the great joys of summer is to throw a slab of meat on the grill, which is a throwback to the days when meat eating became a key factor in the evolution of modern man. The popularity of barbecuing was emphasized last weekend when over 10,000 people attended the Winnipeg Free Press Pit Masters Championship at the Red River Exhibition Park, and partook of slow cooked and smoked ribs, pork, brisket and chicken. 
But it’s interesting to note than vegans (do not consume animal products) deny meat eating influenced human evolution, insisting that hominins (humans and their bipedal predecessors) were always vegetarians and so should remain so to this day. That is an argument made in Kathy Freston’s book, Shattering the Meat Myth: Humans are Natural Vegetarians. But to believe Freston is to ignore millions of years of evolution, as well as the evidence behind the evolution. The early hominins who were solely vegetarians lost the evolutionary battle, while the early meat eaters thrived and evolved into the subsequent Homo genus that led to Homo sapiens (modern man).
A team of researchers led by Vincent Balter, of Ecole Normale Supérieure de Lyon, analysed the enamel from fossil teeth  — ratios of calcium, barium and strontium levels allow scientists to determine the types of food consumed and where — belonging to Australopithecus africanus (one of several australopithecines that lived four to two million years ago), Paranthropus robustus and early Homo species, which were all from South Africa (Scientific American article by Katherine Harmon, August 8, 2012). Their research found that the hominin Australopithecus africanus which lived from three million to two million years ago, consumed a wide variety of foods, including meat, leaves and fruits, allowing them to be more flexible and shift with food availability in different seasons. The result was that they always had something available to eat. 
On the other hand, Paranthropus, which lived between 2.7 million and one million years ago, was primarily a plant eater and as such had a limited range. This hominin is noted for its large sagittal crest atop the skull with was used to anchor the large jaw muscles needed to chew rough fibrous plant material. Because of its massive jaw structure and big grinding molars, one specimen of Paranthropus was nicknamed the “nutcracker man.” But this is a bit of a misnomer, as carbon isotope ratio studies of Paranthropus teeth show it consumed a high quantity of grasses and sedges, rather than nuts. It was eating at the same table as the ancestors of zebras, warthogs and hippos, according to a 2011 University of Utah study. In addition, Paranthropus needed a really big gut to process the plant material (fossil rib cages show that its belly protruded), since grasses and sedges are nutritiously poor and consuming a higher volume such food is required. The 1.3-metre-tall hominin can be likened to today’s gorilla, a plant eater that has to eat conspicuous amounts of plant stuff and thus has an enormous digestive system, resulting in a large protruding belly — the proverbial pot-belly of all pot-bellies. 
Meanwhile, 1.4-metre-tall meat-eating Australopithecus possessed teeth that had diminished in size. Large grinding teeth aren’t needed when you can scavenge soft meat from carcasses on the African plains nor find fruit in trees. Australopithecus still had a large gut, as it  consumed more fruits and plants than meat — animal carcasses to scavenge are not always available — but the hominin was headed toward the evolution of a new species, while Paranthropus was an evolutionary dead end.
Australopithecus gave rise to Homo Habilis (Handy Man) about 2.5 million years ago, which was the species in a direct evolutionary path to Homo sapiens. Habilis lived at the same time as Paranthropus and had one great advantage — it made tools. Paranthropus didn’t need stone tools as it had those massive grinding molars, so the great technological leap forward was limited to those who had to butcher a carcass to obtain meat and crack open bones to extract fat-rich marrow (tell-tale cut marks on bones from stone tools provide the evidence of butchering). All that Paranthropus required to get at starchy roots and tasty termites was a stick, which chimpanzees, with their similar brain size, employ today to catch termites. 
It’s also quite likely that Australopithecus hefted flaked stone tools to smash bones of scavenged carcasses to extract the marrow, and thus obtained a savory energy boost.
Meat is a concentrated form of energy and provided the calories needed to fuel the requirements for the evolution of a larger brain. Essentially, we didn’t evolve to eat meat, but evolved because we ate meat. New species of hominin came and went, but those that ate meat led to modern man. In the case of Habilis, its brain was 30 per cent largerr than its ancestor Australopithecus. The tests by the scientists also revealed that Habilis ate more meat than Australopithecus.
Meat also meant the expenditure of less energy in foraging for and consuming food. If modern man followed the vegetarian diet of Paranthropus, “The daily mountain of fruit and vegetables would mean a six-hour chewing marathon,” wrote Clare Kingston in BBC Horizon on March 2, 2012.
The discovery that meat could be cooked over a fire may have happened accidentally, but it was “arguably the biggest increase in the quality of the diet in the whole of the history of life,” according to Harvard professor Richard Wrangham. The discovery of cooking is attributed to a fire-making species of the genus Homo, and occurred some 1.8 million years ago. Homo erectus had an even bigger brain than Habilis, as well as a smaller jaw and teeth.
“Cooking makes our guts smaller,” added Wrangham. Cooking breaks down cells so that less processing by the digestive system is required, which also includes cooked vegetables. In early hominins, cooking meat and the resulting smaller gut freed up energy to increase the size of the brain. And with its small gut, Erectus could run more efficiently than its ancestors. Professors Peter Wheeler and Leslie Aiollo from Liverpool John Moores University found that the reduction in our digestive system was exactly the same amount that our brains grew; that is, 20 per cent.
But an all-meat diet isn’t what humans evolved solely to eat. Any healthy diet has to be balanced with fruits and vegetables, etc. And for the herbivores in the crowd, there are also equally healthy alternatives to animal products, which guarantee the appropriate amount of protein and vitamins are being consumed. 
Today, with diversity of year-round food available, we have a choice between being omnivores or herbivores, although hominin evolution favoured the former and not the later. So don’t feel guilty if you want to take advantage of the remaining days of summer by throwing a slab of red meat on the grill — it’s a natural thing to do.