Diet and evolution: can we afford to go back to our roots?

  • July 15, 2013

"About 2.5-million years ago there were two groups of hominins"

Our culinary obsession and huge appetite for food is having a detrimental impact on the planet, with a serious global focus on food security and sustainability.

In 2006 the United Nations issued a warning, linking animal farming to high greenhouse gas emissions and other environmental damage, and implying that eating meat in the volumes we do equals disaster in the long run.

According to the Mail & Guardian, a report by the United Nations' Food and Agriculture Organisation claims that by 2050, with a projected world population of 9-billion, we won't be able to feed everyone at current levels of food production. The reporter proposes eating insects as part of our staple diet – a practice called entomophagy, already quite common around the world.

The global warming phenomenon has sparked a wave of ethical eating spin-offs, from farmers' markets to organic and free-range produce and popular eating plans like the Paleo diet. The diet advocates a higher intake of protein, fibre, omega-3 fats and more vitamins, minerals and antioxidants, combined with fewer carbohydrates, processed, salty foods and acidic foods.

The diet, which is believed to improve health, minimise the risk of chronic disease and encourage weight loss, is based on modern foods that mimic those consumed by pre-agricultural, hunter-gatherer Paleolithic ancestors. The era in question is from about 2.5-million years ago until about 10 000 years ago, when humans started cultivating crops and raising animals for food. It is here that we notice a rise in the occurrence of heart disease, obesity, cancer, diabetes and other inflammatory ailments.

But were our ancestors fit and healthy? According to critics of the Paleo diet, our ancestors did not live beyond 40 – in fact, death before 15 was far more common – and they may not have had the best immune systems or sanitation, leaving them open to parasitic infestation, high cholesterol and other bacterial/viral infections.

According to one Scientific American writer, it is ludicrous to promote a single Paleo diet as there were four different types of hunter-gatherers across the globe and no definitive optimal diet. The Paleo diet is described as one "founded on privilege rather than logic".

Going back to the meaty debate, according to a Worldwatch Institute survey, people in South Africa eat in excess of 17kg of beef, 24kg of poultry and 4kg of mutton per year.

Although human beings have long been omnivorous, there has always been a split in our tendencies. According to Brendon Billings, Maropeng's Bone Detective and University of the Witwatersrand scientist, about 2.5-million years ago there were two groups of hominins who would not have looked entirely human, but who walked upright.

Less meat, and more fruit and vegetables?

One group preferred vegetables, but they did eat a bit of meat. Everything they ate was raw, and they had very different jaws to ours – big, powerful jaws for crushing seeds, hard nuts and other vegetation. "Basically, this animal had a tough consistency in the diet," says Billings.

The other group ate a balance of meat and vegetable matter, and it is believed that they were able to make fire, or as Billings suggests, perhaps they were foraging and would opportunistically find a carcass that had been caught in a veld fire or fire caused by lightning. So they could eat cooked food. They had much smaller jaws and teeth, more similar to ours.

"This animal had a less consistent dependence on harder foods," Billings explains, adding that recent data of micro-wear on tooth structure indicates that both groups had a similar diet but the one (robustus) is more consistent with a harder, tougher diet than the other (gracile australopithicines).

No guesses as to which group would evolve into human beings. Our direct ancestors, archaic modern humans, thought to have derived from Homo ergaster, share the same genus as our own species, Homo sapiens. Fossil records indicate that their evolutionary line came to an end just over 1-million years ago.

Scientists say that eating meat was essential as the intake of protein and the synthesis of the muscles and brain, led to the brain developing over the next 2-million years. Protein ingestion never resulted in brain development per se, but provided the means to accommodate a developing brain. Interestingly, Billings says insects provided a good supply of protein to accommodate the needs required to sustain a developing brain.

The earliest fossil evidence of controlled fire in southern Africa – the first ever South African “braai” – was discovered at Swartkrans and dates back about 1-million years. The latest thinking is that perhaps there may be an evolutionary need to change the way we eat.

While diet may have played a big part in our evolution, the big question now is whether we choose to evolve in order to save our environment. Time, perhaps, to ponder on the wise words of Albert Einstein: "Nothing will benefit human health and increase chances of survival of life on Earth as much as the evolution to a vegetarian diet."

For more interesting food facts, visit www.maropeng.co.za or visit www.worldwatch.org. To book for the next Bone Detectives Tour on 27 July, followed by dinner with Brendon Billings (special B&B hotel rates apply) contact 014 577 9000. Please note this tour is for adults only, and commences at 18h00 with welcome drinks at the Maropeng Boutique Hotel.

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