Evolution, not science, drives our urge for healthy foods

We poor humans believe against all reason that diet makes a big difference to our survival

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VANCOUVER, BC, Apr 28, 2015/ Troy Media/ – Healthy eating in general doesn’t have much of a scientific basis.

Avoiding fat, salt, and sugar and loading up on fibre and antioxidants is widely credited with providing major health gains, but the best studies available show that those gains are tiny at best, and more likely just imaginary.

Where does this strange and breathtaking gap between what we believe and scientific proof come from? Our brains may be set up to swallow the bait of food beliefs. Here’s what I think is going on.

Complicated relationship to “healthy” foods

We human beings, as cultural creatures, have a complicated relationship with food. Eating has all sorts of symbolic meanings: to celebrate, to enjoy, to nourish, to satisfy, to incorporate. But as it has worked its way down through biologic history, nourishment is no metaphor. Its meaning is survival.

No banana, no monkey. Food is so necessary for life that anything that enables, encourages or protects successful feeding will be an evolutionary winner and become a prominent feature of the population.

The myth behind healthy foods

Our biological ancestors would have found it complicated and dangerous to get, evaluate, hoard and share food. As early humans started to communicate and think logically, the ones who practised vigilance, calculation, planning and shared group behaviour in keeping themselves fed would have tended to be successful. And natural selection would have favoured those behavioural characteristics.

So one plausible explanation for the almost universal belief in healthy eating myths, along with an awful lot of weird pre-scientific tribal ideology, is that food’s terrible importance has caused our brains to be structured to encourage us to succeed at getting safe nourishing food. And this would include helping us to follow prevailing rules about what to eat.

There is some informed support for this. Evolutionary psychologists Leda Cosmides and John Tooby tell us “. . . a handful of consequences – food, water, pain – are “intrinsically” reinforcing (i.e., the fact that these consequences are capable of changing the probability of a subsequent behaviour is a design feature of the brain)” (My italics; ref 1). Social psychologist and food expert Paul Rozin agrees (ref 2).

It also seems reasonable that for characteristics as universally survival-promoting as effective food behaviour, we might be hard-wired to seek prevailing feelings and behaviour about food and feeding.

Solomon Katz, an anthropologist at the University of Pennsylvania, explains how food ideas could evolve. First, there is a slow, brain-biological mechanism where effective foraging behaviour is reflected in brain characteristics. There is also a faster mechanism which gives us the same kind of predispositions through folklore and learning from elders.

So there may be good evolutionary and cultural reasons why we poor humans believe so firmly and against all reason that diet makes a big difference to our survival. It is not so much that the evolved brain, forced to focus on nutrition to survive, encourages a particular type of feeding pattern (hiding food, sharing with tribe members, avoiding fish) as that our brains encourage us to search for tried and true ways of thinking about food.

This leads us to go after the meal that nourishes us and avoid a spoiled, rotten and poisonous one.

I can’t think of a better explanation for why we think we can diet our way to a long disease-free life when science clearly tells us the opposite.

Healthy foods and eating unscientific

When humans go looking for food ideas, healthy eating is doubly attractive. Not only is it the modern version of tribal wisdom, but that tribal wisdom is also popularly thought to be based on the most powerful ideology around: science.

And so we beat that tribal drum and chant the mantra: blueberries, pomegranate, coarse whole-grain good; dairy fat, red meat, pepperoni, refined flour bad. It doesn’t matter that there’s almost no scientific substance to that mythology. Instinctively and culturally, it is completely satisfying.


  1. John Tooby and Leda Cosmides, “Conceptual foundations of evolutionary psychology,” In D. M. Buss (Ed.), The Handbook of Evolutionary Psychology (pp. 5-67). (Hoboken, NJ: Wiley, (2005).
  2. Paul Rozin, “Food is fundamental, fun, frightening, and far-reaching,” Social Research, 66, 9-30, (1999).

John Sloan is a family physician whose practice is confined to home care of frail elderly people, and avoiding institutional care of these patients. He has published numerous articles and several books on healthcare. His most recent ebook is Forbidden Food: How Science Says you can Eat what you Like and Like what you Eat.

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