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December 17, 2006

The Missing Variable: Philosophy

By Gus Van Horn from Gus Van Horn,cross-posted by MetaBlog

Great. Thanks to sloppy journalism about a statistical study, everyone who knows a crusader for vegetarianism can look forward to being called an idiot. Again. And with "proof", this time. From the first linked article:

Frequently dismissed as cranks, their fussy eating habits tend to make them unpopular with dinner party hosts and guests alike.

But now it seems they may have the last laugh, with research showing vegetarians are more intelligent than their meat-eating friends.

Yep. These are the first two lines of the article: all many people will have time to read, all any leftist needs to know, and all that will fit into any of the sound bites we're all going to be subjected to non-stop from every direction in the broadcast media. Prepare to have it beaten into your skull that vegetarians have been proven, once and for all, to be more intelligent than everyone else.

And we all know that intelligence is exactly the same thing as infallibility.

Essentially, the news articles I have seen on this are fluff used to disguise one small detail about the study they are so busy touting: The study doesn't really prove anything about the intelligence of vegetarians or any implications about it concerning the alleged merits of vegetarianism.

There was no difference in IQ between strict vegetarians and those who classed themselves as veggie but still ate fish or chicken.

However, vegans - vegetarians who also avoid dairy products - scored significantly lower, averaging an IQ score of 95 at the age of 10.

Researcher Dr Catharine Gale said there could be several explanations for the findings, including intelligent people being more likely to consider both animal welfare issues and the possible health benefits of a vegetarian diet. [bold added]

Got that? All this study (third link) shows is that people who consider themselves vegetarians (even if they are not) scored a few points higher on IQ tests -- as children. We'll even ignore that pesky group of nine vegans who were below average intelligence overall.

And on top of that, the paper admits that:

[S]ome attrition has occurred in the cohort over time. The participants at the 30 year follow-up did gain significantly higher IQ scores at age 10 than those who did not take part, although the size of the differences was modest (0.3 of a standard deviation). Unless the relation between childhood mental ability and vegetarianism is in the opposite direction in non-participants, little bias will have been introduced in our study.

Given that "some attrition" means that over a third of the original 17,198 subjects did not report on vegetarian status as adults and that the article's own literature review admits that "Findings are mixed" in previous studies that attempted to link vegetarianism to educational attainment (which is a "strong correlate of mental ability"), this finding has to be viewed as a preliminary addition to "mixed" evidence at best.

But let's entertain the possibility for a moment that Gale et al. are right, as I suspect they are. Future studies vindicate them. What have they shown? We'll start with some of their own ruminations:

Although the vegetarians in this cohort were, on average, more intelligent, better educated, and of higher occupational social class than the non-vegetarians, these socioeconomic advantages were not reflected in their income. It may be that ethical considerations determined not just their diet but also their choice of employment. Compared with non-vegetarians, vegetarians were less likely to be working in the private sector and more likely to be working in charitable organisations, local government, or education: 17% of the vegetarians worked in education compared with 9% of non-vegetarians. When asked, as part of the follow-up survey, what they thought of the statement "The government should redistribute income," 50% of vegetarians said they agreed compared with 41% of nonvegetarians, and this proportion was even higher among male vegetarians (61% v 42%). Such views may not be compatible with a career in the more lucrative employment sectors. [bold added]

In other words, the vegetarians are more left-wing than non-vegetarians! This comes as no surprise since those who are more intelligent generally remain in school longer, where they are subjected to more of the same relentless left-wing indoctrination than their counterparts. I would have loved to see a statistical analysis of that! Or even the slightest acknowlegement of that fact in the news media.

Credit the scientists, at least, with providing what Paul Harvey would call, "the rest of the story". The paper openly admits the objections one might raise to its conclusions and even states several times that vegetarianism is often chosen for "ethical" (i.e., philosophical) reasons regardless of any alleged health benefits.

Although our results suggest that children who are more intelligent may be more likely to become vegetarian as adolescents or as young adults, it does not rule out the possibility that such a diet might have some beneficial effect on subsequent cognitive performance. Might the nature of the vegetarians' diet in this cohort have enhanced their apparently superior brain power? Was this the mechanism that helped them to achieve the disproportionate number of higher degrees? Benjamin Franklin and George Bernard Shaw, both ardent vegetarians, would have us believe so. According to Shaw in an article published in The Star in 1890, "A mind of the calibre of mine cannot derive its nutriment from cows."

...

Alternatively it is possible that the link between childhood IQ and vegetarianism in later life is not on a causal chain of mechanisms related to health. People with a higher IQ may well differ from those with less superior brain power in many of their lifestyle decisions: for instance, choice of newspaper, type of books read, preferred form of entertainment. The association between IQ and vegetarianism may be merely an example of many other lifestyle preferences that might be expected to vary with intelligence but which may or may not have implications for health. [bold added]

The bit about the study not "ruling out" an intelligence boost due to vegetarianism is worth noting. The study has nothing whatsoever to say about whether a vegetarian diet might yield the benefits to intelligence alleged by some famous vegetarians in the past: Those who called themselves vegetarians started out that way and there was no difference between real and fake vegetarians among that group!

In other words, this study reinforces the point that it is a person's philosophy that affects whether they make a lifestyle choice -- such as to become a vegetarian -- that may conflict with their own self-interest and whose benefits (if any) have not been firmly established.

It is too bad that the news media have chosen to pretend that science has vindicated vegetarianism. In fact, this study can only point to a correlation between a mildly higher IQ (whatever that means) and a desire to be known as a vegetarian! Not only can it merely "not rule out" the notion that vegetarianism enhances cognitive function, it cannot even state that actual vegetarians really did start out as more intelligent.

Journalism about science really makes me want to pull my hair out sometimes.

-- CAV

Originally posted by Gus Van Horn from Gus Van Horn, ReBlogged for David Veksler