Wednesday, 24 August 2011

Why Vegetarians Are More Intelligent than Meat Eaters


What an awful article, devoid of reason, ill-constructed, unreferenced, and quite aside from anyone's opinion on the topic at hand, a fine example of really bad science.

Another evolutionarily novel value is vegetarianism. It is exceedingly unnatural for humans to be vegetarian.

Humans are naturally omnivorous. We are evolutionarily designed to eat both animal meat and plants. Anyone who eschewed animal protein and ate only vegetables in the ancestral environment, in the face of constant food scarcity and precariousness of its supply, was not likely to have survived long enough and stayed healthy enough to have left many offspring. So such a person is not likely to have become our ancestors. On the other hand, anyone who preferentially ate animal protein and fat in the ancestral environment would have been much more likely to live longer and stay healthier. They are therefore much more likely to have become our ancestors.

Ok, with you so far.

The Hypothesis would predict that more intelligent individuals are more likely to choose to become a vegetarian than less intelligent individuals.

Eh? Wait a minute, you've just been telling us how those that avoided eating meat were likely to die and not pass on their genes. From that information, you hypothesize that more intelligent individuals are likely to become vegetarian??

(I wouldn't usually use double question marks, but I was going to write "?!" and then the chess-player in me realised that in chess notation, "?!" means "a dubious move, but one that is hard to refute", which would be inappropriate here. So I went with "??" instead, which means "Blunder".)

This indeed appears to be the case. Among the British respondents in the National Child Development Study, those who are vegetarian at age 42 have significantly higher childhood general intelligence than those who are not vegetarian at age 42. (Childhood general intelligence was measured with 11 different cognitive tests at three ages before 16.) Vegetarians have the mean childhood IQ of 109.1 whereas meat eaters have the mean childhood IQ of 100.9. The difference is large and highly statistically significant.

Which is of course why they cited their source, to show these statistics. Oh wait, no, they didn't.

And if correct? Correlation / causation, come on, get a grip. We need more pirates.

The fact that the difference in childhood IQ between vegetarians and meat eaters is larger among men than among women makes sense in light of the historical division of labor between the sexes. Throughout evolutionary history, men have traditionally hunted animals for their meat while women have traditionally gathered plant food. So vegetarianism – a complete and total eschewal of animal meat – should be even more evolutionarily novel and unnatural for men than for women. Women are 60% more likely to be vegetarians than men are (3.33% vs. 2.07%).


Since it's even more evolutionarily novel and unnatural for men than for women, it is more likely to have been adopted by those with a masochistic death-wish, which is not necessarily a strong corollary of intelligence.

Childhood general intelligence has a significantly positive effect on the likelihood of vegetarianism at age 42, even net of a large number of social and demographic factors, such as sex, whether ever married, whether currently married, education, income, religion, religiosity, social class at birth, mother’s education, and father’s education, both in the full sample and among men and among women separately. There appears very little doubt that more intelligent children are more likely to grow up to become vegetarian as adults in the United Kingdom. One standard deviation (15 points) increase in childhood IQ increases the odds of adult vegetarianism by 37% among women and by 48% among men.

Here, since there appears to be a correlation (assuming the numbers are correct, which I wouldn't count on, given some other numbers on the site that are clearly incorrect), I would offer an alternative explanation, since theirs doesn't make sense.

My offered (and more likely) possible explanation is that poor people can't afford to be fussy eaters, and uneducated people don't read much. Therefore, it's less likely that they will find it convenient to be vegetarian, or read so many rhetoric-heavy logic-light arguments for vegetarianism.

In case you're wondering, yes, I'd suggest that poor uneducated people are less likely to be intelligent, because:

a) Poverty and lack of education mean a person is less likely to pursue things that will increase their intelligence
b) Those who are poor and uneducated but intelligent will rise above those conditions

[anecdotal aside]

I was born into:

a) considerable poverty (I remember as a child being scolded for not leaving a paper towel out to dry for reusal, as "we couldn't afford the wastage", being scolded for, when washing dishes not turning off the hot tap in between individual dishes ("we couldn't afford the wastage"), the woman who passed for a mother wrapped anything she could find as presents for birthday, Christmas, etc - I was the poorest kid at a rather poor poor-kids' school)
b) terrible education (my first school was the worst of the worst, and has long since been closed down - enough said); I lived with my single mother who was unable to teach me almost anything of value due to her own absence of intelligence or useful knowledge.

However, the squalor of my youth gave me (as it failed to do for many) a thirsty ambition to excel beyond that world, and I withdrew into my bedroom and my mind; I read what books I could get my hands on, educated myself, won a scholarship to a good school, and set about my general path to world conquest etc.

For what it's worth, last I had it checked, my IQ was 142.5. It's probably higher now, as I understand the ability to solve those little puzzles usually goes up rather than down as one applies problem-solving skills in life in general.

I'm not vegetarian, and furthermore, when I don't get enough animal-source protein and fat, my blood sugar levels drop and so does my intelligence.

[/anecdotal aside]

Interestingly, the strong association between childhood intelligence and adult vegetarianism is not replicated in the US.

I'm going to guess that it has something to do with the sample size.

Vegetarians in early adulthood do have significantly higher childhood intelligence in junior high and high school, but the difference is not large (101.5 vs. 99.3). And it is only significant among women (101.4 vs. 98.5), not among men (101.7 vs. 100.1). This is very strange given the historical division of labor noted above. The significant effect of childhood intelligence on adult vegetarianism among Americans disappears entirely once mother’s or father’s education or religion is statistically controlled.

Funny, that.

It is not at all clear to me why the difference in childhood intelligence between vegetarians and meat eaters is so much larger and stronger in the United Kingdom than in the United States. Apart from the national differences between the UK and the US, the two samples also come from different generations. The British NCDS respondents were all born in March 1958, whereas the American Add Health respondents were born between 1974 and 1983. I am not sure if it is the national differences or generational differences, or something entirely different, that account for the observed difference in the association between childhood intelligence and adult vegetarianism.

Yep. Could be those things, or... sample size.

So, you were going to tell us "Why Vegetarians Are More Intelligent than Meat Eaters".

I'm still waiting.