Evolution theory is food for thought

AS I eye the copious vittles being prepared for Christmas, I remember reading that our jaw muscles are much weaker than those of our ancestors.

The next time I go to the circus I will worry about the girl hanging from the flying trapeze by her teeth. While our jaw muscles extend only to our ears — one can feel them, by clenching and unclenching one’s teeth — those of the apes, our cousins, run to the tops of their heads.

One theory holds that this has happened because, after harnessing fire, we began to cook our food rather than eating it raw. Fire was, no doubt, utilised by early man. It could be captured from trees struck by lightning, from volcanic vents or from grassland set on fire by the sun’s heat magnified by shards of glass-like obsidian. Also, early man might have come upon hot springs and tossed in the carcass of an animal by way of experiment.

Eating cooked food caused our jaw muscles, mouths, teeth, stomach and intestines to shrink.

However, according to Dr Richard Wrangham, Harvard Professor of Biological Anthropology and author of How Cooking Made Us Human, the energy that would have been expended in chewing raw food was usefully diverted to increasing brain size. It is generally agreed that the change from a vegetable to a meat diet made hominoids cleverer. The more intense the source of protein, the more fuel for intellectual growth. Wrangham tells us it was the cooking that worked the magic. Chewing raw meat saps much of its energy benefit, while cooking vegetables allowed mankind to utilise varieties not palatable otherwise. Volunteers fed only on raw meat and vegetables grew weaker and slowly starved and more than half the women on such diets became infertile. However, might this not simply be a result of the anatomical changes in modern man?

It is obvious that these changes have occurred not only in our food-processing equipment but in our overall physique. We do not have the barrel bodies, short legs, simian arms of our primate cousins or even the pronounced brow ridges of relatively recent Cro-Magnon man, now more accurately called EMHs, Early Modern Humans. Skulls of EMHs found in France had a cranial capacity 15% larger than ours. Have we less grey matter or are brains, like computers, becoming more efficient as they shrink?

It may be that the explanation for the larger skulls was tougher food, albeit cooked but caught or gathered in the wild, and a colder climate. We are less hairy than our ancestors and Wrangham postulates that our development of fire for heating may account for this; also that human society may have developed from sitting around the fire — chewing the fat, so to speak — and that the genders may have been separated because the women had to keep the home fires burning while the men went off hunting for something to cook.

Other recent DNA developments indicate that Neanderthal man — who also had larger brains than ours — were closer to us than previously believed. It had been thought that we, Homo sapiens, wiped out Homo neanderthalensis. Bill Bryson, in his book, Mother Tongue, notes that the Neanderthal voice box lacked the sophistication of ours and thinks this would have given us the upper hand. According to Robert McCarthy, an anthropologist at Florida Atlantic University, writing in New Scientist in 2008, “They [Neanderthals] wouldn’t have been able to produce these quantal vowels that form the basis of spoken language.”

However, humans and Neanderthals coexisted for 30,000 years. In a US journal, Proceedings of the National Academy of Sciences, 2006, researchers posited Neanderthals were not slaughtered by us but became extinct by absorption — by interbreeding with humans — and that we have traces of the Neanderthal in our blood.

The unique genetic makeup and language of the Basques have led to suggestions that Neanderthals and humans may have interbred in northern Spain. According to a respected DNA expert, Dr ZH Rosser, the populations most closely related to the Basques are in Cornwall, followed closely by Wales, Ireland and Scotland. Genome profiling reveals that Neanderthals had fair skin and freckles and that the red hair gene (rufiosity) had Neanderthal origins.

Evidence of Neanderthals has been found in Britain but not yet in Ireland. Were the Firbolg Neanderthals? Perhaps they boiled elk off-cuts in fulacht-fias and invited the newly arrived Celts to dinner.