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Once Upon a Time…

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Once upon a time, it was a good thing to be fat. No, seriously, it was. Of course, that was some time ago, and well, we were all a lot hairier and had a tendency to eat our meat raw – but it was still a good thing to be able to put on weight. It was so good, in fact, that most of those who survived the daily challenges of life, were those who could put on weight.

Okay, that was 10,000 years ago, but in reality, that’s not even a blink in terms of the evolution of the human body.

10,000 years ago, we humans – Homo sapiens– were basically foragers or hunter-gatherers. We lived off what we could find, catch or kill. According to Anna Bellisari in her article for Obesity Review:

The diet of Palaeolithic foragers was probably the most nutrient-dense and healthful in all of human history. The ‘Palaeolithic Diet’ has been reconstructed and its nutritional impact evaluated by combining archaeological data with observations of the few remaining modern foraging peoples. Daily calorie consumption was high, an average of 3000 calories per day, and meat constituted a significant 35–50% of the diet, with wild plant foods making up the remainder.

It goes without saying that if you spend your days finding, catching and killing your evening meal, there’s not a lot of time – or energy – left for kicking back for an evening of Simpsons re-runs.

Bellisari’s article goes much deeper into the history of obesity. In particular, she looks at how a range of genetic factors brought into being the Homo sapiens most likely to survive the harsh and unforgiving conditions of the time. And conditions were getting worse. Wild game became harder to find – which was a serious problem if 50% of your diet was meat. We hadn’t quite learned that farming and the cultivation of crops was a more reliable way of obtaining food, so survival wasn’t guaranteed for anybody. But if you found food, and you could eat more of it, and your body stored it automatically, then when it was harder to find food, you were less likely to starve.

But there’s more to it than simply having genes that helped us store food for another day. In fact, our very ability to think about such things, to develop language and voice our opinions can be traced back to our ability to store fat.

As Jesse Bering writes in Scientific American:

… human fatness evolved, and it was in fact a remarkable evolutionary innovation. Compared to any other primate species, human beings have substantially greater levels of body fatness and reduced levels of muscle mass… A human baby lacked [a chimp’s] muscle mass and could barely sit up at 6 months, all that baby fat was busy giving them a cognitive advantage by providing these human infants with all that stored energy for costly brain metabolism and simultaneously reducing their energy expenditure by rendering them largely immobile. In other words, human evolution underwent a sort of trade-off of brawn for brains; and genes for fatness, especially as they are expressed during the long dependent period of human infancy when babies are undergoing rapid, radical cognitive change, played a vital role in the origins of human intelligence.

Despite what the media tries to tell us, obesity – storing fat on our bodies – is not something we have invented. It’s been around a very, very long time. Jesse Bering writes:

If you’re an obese person and can trace your being significantly overweight to some combination of genetic factors—over 600 genes, markers and chromosomal regions have been associated with human obesity phenotypes using the Human Genome Obesity Map, and these heritable factors include everything from individual differences in metabolic rates to the tendency to engage in spontaneous physical activity to specific syndromes involving deficiencies of energy-regulating peptides—there’s a good chance that your genetic makeup would have given you a leg-up over your “naturally skinny” peers if only you’d been born about 10,000 years earlier. This is probably why you have these genetic contributions to your obesity today, in fact, because they helped your adipose-pocketing ancestors survive during food shortages.

So putting on fat was a good thing, and there was a very good reason our bodies had the ability to do this – so that we could survive, and our brains grow bigger, making us smarter and able to problem-solve and invent things like farming.

And it’s even possible that without the ability to put on weight, there might not be too many humans around today.

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2 Comments

  1. Glenn McCrabb says:

    An interesting post, mor from what was left out than what was left in. When you take into account the lifespan of the average human 10,000 years ago and couple that with their average body fat I think that today’s obesity crisis is still a problem.

    1. Mackenzie says:

      I agree that obesity is still an important issue, but this research does at least show that the obesity crisis today does have a heritage that goes way back beyond McDonalds. These genes don’t make people fat, but they do set up a genetic predisposition for some people to store fat much quicker and easier than others.