The holiday season is a wonderful thing. But many people like me struggle in the following months to shed the pounds gained during this season. Food is actually the least of my priorities. Some people live to eat - I am definitely one of them. But I do envy people who can eat as much as they want and don’t put on weight, like a friend of mine (he can eat as much chocolate as he wants!)
A lot of our food preferences and eating behaviours may be written in our genes. The most famous example being lactose intolerance. The evolution of lactase persistence in response to pastoral behaviour, so if there is no ancestry of farming and herding written into your genes, you are unlikely to have the ability to digest milk and dairy products as a grown-up. Adult mammals do not consume milk, as a rule. Therefore living hunter-gatherers (who never had a history of herding), like the Inuit, are largely lactose intolerant.
Hannah Critchlow writes in The Science of Fate (2019) that there is a strong genetic component to our food preferences, both genetically and epigenetically. What your grandparents had for dinner may actually influence your own food choices. Certain alleles of the FTO (also known as "fatso") gene predispose people to overweight.
At the beginning of the year, I had my genome sequenced and I found out it’s written in my genes. There it says clearly: increased BMI (I bet George’s says the same):
Like George Lucas I am a bit overweight. Oh, George, what were the odds? Like you I was a skinny lad. Who would have thought then?
When reading George Lucas’ biography I marvelled at how he subsisted on the fruits of the vending machine at film academy. A diet based on chips and coke while making his first movie - that could have been me. In fact, George Lucas and I share the same personality type: INFP. Yes, introverts like us are usually thinner. In fact, extroverts are more likely to become overweight than us. They tend to eat more as they are more “energetic” - well often enough they do also move more, to be fair. Extroverts are much more likely to heave their buts out of their chair and get going. Yet, introverts like us, George, are often very picky and small eaters. And I used to be underweight until my 30s.
I come from a family with ectomorph body types, married a woman with ectomorph body type and have children with ectomorph body types. My introverted sons are extremely picky eaters, who manage to drive their mom crazy at times. My younger son would eat only a few foods like chicken nuggets, French fries and pasta (without any sauce and seasoning!). What’s more, ectomorphs don’t usually put on a lot of weight, like endomorphs do (mesomorphs generally put on weight quickly but also lose it quickly).
In fact, these body types map well onto the different ancestral subsistence types:
- Ectomorph: lightweight, low-metabolism, ideal for hunting and gathering, built for endurance (most marathon runners)
- Mesomorph: athletic, high metabolism, ideal for extreme, but short burst of energy expenditure, built for power and speed (most football players, sprinters, etc.)
- Endomorph: strong body type, ideal for long, hard routine work, built for stamina (many wrestlers, e.g John Cena)
So, why did me and George end up overweight as hunter-gatherer types? Here are the personality traits in the Big 5 that correlate with overweight (source):
- extraversion (positively correlated)
- neuroticism (is actually associated with both over- and underweight!)
- conscientiousness (negatively correlated)
Both George and I are introverts, which is actually negatively correlated with obesity. Neuroticism: yes, me definitely (and I have a hunch George is too). I do a lot of eating out of frustration and procrastination. Conscientiousness: I am admittedly low on conscientiousness, and so is probably Geroge, as this trait correlates with our P (in INFP) and impulse control. That said, genes aren’t necessarily fate, nor is your personality type. There are plenty of INFPs who are still as skinny in old age as they were when little kids.
Regarding my hunter-gatherer hypothesis, I have noticed the following trends for hunter-gatherer type (this is no way a scientific analysis though, just my personal experience). Hunter-gatherer types are the most likely to:
- have food allergies like lactose intolerance and Celiac disease
- be vegetarians (even though is probably more likely true for F/gatherer types
- be picky and small eaters in childhood
- have stomach aches more frequently in childhood
- have irritable bowel syndrome (IBS)
- be skinny or overweight
- suffer from anorexia nervosa or bulimia
- to either subsist on junk for or high-quality foods only.
Like so often in life we hunter-gather types have a tendency towards extremes. Like George in his student years, I could easily subsist on junk food, whereas my ENFJ wife wouldn’t eat anything that contains an ingredient she would disapprove of. Everything has to be fresh, organic, containing only certain types of fat, etc. She even disapproves of me eating tuna.
We are often also extremes when it comes to our weight, often skinny, but when we become overweight we look like balloons. When it comes to eating disorders INFJs (introverted, highly conscientious) are the ones who are most likely at risk for anorexia, whereas ENFPs (extraverted, low on conscientiousness) are most likely at risk for bulimia. This is also true for men who suffer from bulimia (Ed Sheeran is a famous ENFP who suffered from bulimia). A similar correlation is probably also true for junk food vs high-quality foods.
As I mentioned above, these aren’t scientific facts, just personal observations - and a lot of food for thought. I have always wondered what those real-life ectomorph hunter-gatherers would look like if they lived in our civilisation. I have found an interesting clue. Daniel Everett writes in Don't Sleep, There are Snakes about the Pirahã hunter-gatherers of the Amazon:
Often after a visit to the city of three to six weeks, a Pirahã will return as much as thirty pounds overweight to the village, rolls of fat on their belly and thighs. But within a month or less, they’re back to normal weight. The average Pirahã man or woman weighs between 100 and 125 pounds and stands five feet to five feet four inches tall. They are lean and tough.
What is amazing about this story is that obesity is virtually unknown among hunter-gatherers around the world. Only a few weeks with our lifestyle and those Pirahã hunter-gatherers start to balloon. Fortunately, they quickly return to their normal weight when they take up their natural lifestyle.
If you ever come across a man with rolls of fat on his belly and thighs and who reminds you of the Michelin Man, chances are he is a hunter-gatherer type who has spent too much time in “civilization” and not enough exercising and that he was once lean and tough in his childhood.
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