<link rel="stylesheet" href="//fonts.googleapis.com/css?family=Roboto%3A300%2C400%2C500%2C700%7CRoboto+Slab%3A400%2C700">Evolutionary psychology is riddled with pseudoscience - Filthy Monkey Men

Evolutionary psychology is the study of how evolution has shaped human psychology. Despite not having a particularly creative name, this discipline is critically important in understanding why humans act, think and feel the way we do. Unfortunately for those of interested in why human behaviour can be so bizarre, evolutionary psychology is a field that’s riddled with pseudoscience.

The problem

The big issue stems from how data is gathered. After all, for evolution to influence behaviour that characteristic has to be heritable (i.e., have a genetic foundation). However, establishing a definitive link between a particular behaviour and a gene would require human testing on a scale that would make the Nazis queasy.

Instead, scientists reason that since humans are almost genetically identical then behaviours with a genetic basis should also be very similar between people. So rather than conducting horrific genetic experiments they just look for “universal” behaviours instead. Everyone’s a winner.

The percentage of psychology studies conducted on populations around the world. Europe, North America and other Western (WEIRD) countries make up >90% of it.

The percentage of psychology studies conducted on populations around the world. Europe, North America and other Western (WEIRD) countries make up >90% of it.

Or at least they would be if the evolutionary psychologists were better at looking for these behaviours. A review of psychology research revealed that upwards of 90% of psychology studies are conducted on Westerners1 (and ~85% of those may be performed on undergrads only2). It’s rather hard to make conclusions about behaviours present in all humans when you’re only looking at a really narrow sub-section of humanity.

And sure enough, many of these behaviours stop seeming so universal when you start to study people who aren’t Western university students. Turns out these “universal” behaviours are actually limited to people growing up in a very specific culture3. Even optical illusions affect people from different cultures differently. Our psychology can be that different4.

All of this makes it rather hard to trust claims that evolutionary psychologists looking at Westerners have discovered evolved, universal behaviours.

The Muller-Lyer illusion. The lines are the same length; but people from different cultures have differing levels of success at figuring out this is actually the case

The rebuttal

Of course, many researchers are quick to leap to the defence of evolutionary psychology. They point out that the study which found so much research relies on Westerners surveyed psychology as a whole. Kurzban examined only evolutionary psychology research and found that the actual numbers may be far lower; indicating that only 65% of EP research used Westerners. Although there’s still room for improvement, clearly things aren’t as hopeless for evolutionary psychology as they may first seem.

The use of WEIRD (aka Western) samples by a EP journal (red) and a psychology journal (blue)

In fact, last time I wrote about the issue of sampling in evolutionary psychology several commenters pointed me towards Kurzban’s work in an effort to dispute what I was saying. However I was not convinced. Kurzban examined a single year of publications in a single EP journal. The aforementioned research into the whole of psychology studied six journals for a five year period1. In other words, I suspected Kurzban’s conclusions may not be representative of the whole of EP literature. A larger, more long term survey was needed.

The survey

So I set out to do that survey. I wanted to examine research published between 2003 – 2007 as that was the period examined in the aforementioned survey of psychology as a whole. Thus the two data sets would be comparable. I also looked at research published in 2013; for more up-to-date data.

Unfortunately many evolutionary psychology journals are relatively new,  or moved around during this period and archives were lost in the move. In the end though I was able to find 3 journals that met my criteria: Evolutionary PsychologyHuman Nature and Evolution and Human Behaviour.

So I went through all the research conducted on humans published in those journals during this period. Whilst I was doing this I also looked for whether the research was conducted on university students. Because that would just exacerbate the unrepresentative nature of these samples.

The results

The percentage of evolutionary psychology research conducted on various populations around the world

The percentage of evolutionary psychology research conducted on various populations around the world

The results of this survey are presented in that table. As it shows, on average 75% of evolutionary psychology research uses only Western (aka WEIRD) samples. I’m not sure there’s really much more I can add to that. Clearly there is a significant issue with the sampling practices of evolutionary psychology research.

The vast majority of evolutionary psychology research is potentially inapplicable to non-Westerners. This effectively undermines so many EP ideas it isn’t even funny. So much of our knowledge about the evolution of human behaviour may have to be discarded.

On the plus side, a statistical comparison with the results for the entirety of psychology (which as previously mentioned, uses Western samples in ~95% of cases1) reveals that evolutionary psychology uses Westerners significantly less often. Although I think that’s small comfort in this case. Oh; and it turns out EP research utilises university students about 40% of the time, which is half the rate (~80%2) of psychology as a whole. Again, not sure this is really a cause of celebration.

In short, evolutionary psychology’s reliability is contingent upon the fact its results can be applied to all of humanity. Yet the fact that 75% of research only studies Westerners means that this may not be the case. For all we know 3/4 of EP is basically pseudoscience.


  1. Arnett, J. (2008). The neglected 95%: why American psychology needs to become less American. American Psychologist, 63(7), p.602.

  2. Sears, D. (1986). College sophomores in the laboratory: Influences of a narrow data base on social psychology’s view of human nature. Journal of personality and social psychology, 51(3), p.515.

  3. Henrich, J., Heine, S. and Norenzayan, A. (2010). Beyond WEIRD: Towards a broad-based behavioral science. Behavioral and Brain Sciences, 33(2-3), pp.111–135.

  4. Henrich, J., Heine, S. and Norenzayan, A. (2010). The weirdest people in the world?. Behavioral and brain sciences, 33(2-3), pp.61–83.

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        Just trying to break even really, since i now have to pay for hosting. Ive tried to minimize the impact of the ads. None will ever appear in the middle of an article, for example. If theres one that you think is still located in an annoying position ill see what i can do

        Artem Kaznatcheev · 12th March 2015 at 6:27 pm

        I’d be interested to know more about this (maybe I’ll email you).

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        Adam Benton · 14th March 2015 at 11:15 am

        A lot of ads reward you based on people actually clicking them. As such the link between viewership and revenue isn’t as strong as you might think (up to a certain size; once a site gets very big people start paying just for the eyeballs). Obviously having more viewers increases the chances one of them will click through; but still, some of my most profitable days have been my least busy.

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Lucky Phoumala · 31st December 2014 at 12:52 am

Great article Adam, thanks for taking the time to conduct the research! I’m still currently an undergraduate student (sociology/psychology) however have recently become interested in becoming a research psychologist, with the hope of evolutionary psychology being a specialisation of mine.
Do you still think I should follow this path? It seems like it’d be rather difficult to acquire a sample that could be considered close to being representative of the whole human population.

    Adam Benton · 1st January 2015 at 11:45 am

    Oh definitely. Psychology needs more awareness of this issue. Perhaps one of the most disturbing things i found (and plan on writing a post next week about) was that there was no change over time. Despite all the furore, study and debate people are still relying on WEIRD popularions as much now as they were in the early 2000s.

    And of course, theres also the fact that research only on westerners isnt useless. It can be a great preliminary investigation to identify candidates for further study. The issue is that that study is rarely done

Anonymous · 31st December 2014 at 3:00 am

“psEUdoscience.” It wouldn’t bother me normally, but it is in your title. Other than that, good to see the reliance on e.p.’s WIERD samples quantified.

    Adam Benton · 1st January 2015 at 11:49 am

    Thanks for the correction and the praise

Andre Salzmann · 1st January 2015 at 11:41 am

I studied both psychology and archaeology. So this is an interesting article.

Firstly, it would be a good thing if a site like this could re-numerate the author
for his input to the extent where he could maintain and expand it, not having
to do it only at his own costs. Nothing wrong with that.

Secondly, a while ago a fellow South African wrote on this site that it is an amazing
experience living in this country and being able to observe peoples that are so different
from one another. We have Europeans, Negroids, San, Griequas and some that
are still closely related to the Standlopers (Beachwalkers) from the 1650’s. Obviously
to the extent that one can distinguish these peoples visually. Living intimately with
these peoples, one can distinguish there behavior intellectually. ( This is the
makings of a very interesting and energized life if one is sensitive and interested).

The logical conclusion of mutations being selected by ecological circumstances
should be that different human products developed in different geological areas of
the world. Ice periods in Europe must have necessitated different emotional,
intellectual and cultural attributes than did ares that were permanently warm
and lush or permanently arid and harsh. One just has to take note of the adaptions
observable in the same species in wildlife to realize this.

Therefore, is it correct to group all humans together for EP studies. Should EP
students not study universally evolved human attributes and specific “racial”
attributes ? Geographically induced attributes? I think it would lead us to understand
the “human condition” better and help us to manage it better.It would be quite
disruptive for them to eventually again discover that they have missed the point.

    Adam Benton · 2nd January 2015 at 3:03 pm

    When you look at the bodies of people from different places we do see evidence of different adaptations for different environments. Europeans, for example, tend to be a bit short and squat which appears to have been a way to retain heat during the ice age.

    So it’s not exactly unreasonable to think that behaviours have undergone similar changes. The physical differences aren’t that major so I’m not sure they’d be significant psychological differences, but very minor ones may well exist.

    The issue is, as I said at the beginning of this post, is trying to link behaviour and genes. That’s easy enough when looking at universal traits since people live in different cultures, environments etc. Thus if there is a trait that is still the same it’s likely evolved and not culture, environment etc.

    Yet obviously most Europeans live in a similar environment, culture etc. So if you find a trait present in all Europeans, can we say it’s evolved or is it just the result of the European culture?

    In other words, it might be impossible at this time to reliably figure out if there are such differences between populations, even if they do exist

sergeimorozov · 1st January 2015 at 9:21 pm

I agree 100%.
Moreover, survey data cannot be trusted too, because “Man is not a rational animal, he is a rationalizing animal” (c) Robert A. Heinlein. Men cannot answer survey “as is” in a result. They rationalize own subconscious answers.

    Adam Benton · 1st January 2015 at 11:17 pm

    Im going to have to disagree, since most studies are not simple survegs

Artem Kaznatcheev · 12th March 2015 at 6:24 pm

Although I share your reservations on the reliance on WEIRD participants. I do have a bone to pick with you on this article. Especially when you write:

After all, for evolution to influence behaviour that characteristic has to be heritable (i.e., have a genetic foundation). … scientists reason that since humans are almost genetically identical then behaviours with a genetic basis should also be very similar between people.

There are definitely some that reason as above, but I would need to be convinced that this is the most common reasoning. For most evolutionary explanations, it does not matter if the transmission is genetic or cultural, in fact one of the biggest parts of Henrich’s work (that I linked to above) is arguing that cultural transmission is particularly important and can be studied with the models of evolutionary biology.

Looking for the basis of human behavior (solely or primarily) in genetics seems unreasonably reductive to me. The effect of culture for how we perceive and function in the world is immense, and culture is highly heritable although the transmission is not genetic.However, just because the transmission isn’t genetic doesn’t mean that we can’t apply evolutionary arguments. For instance, you just wrote about language tracing; you can do similar studies for culture tracing. Of course, as this is done, it is important for the evolutionary psychologist to become mindful of when their models have to depart for those used for genetic evolution.

Finally, I think classifying something as pseudoscience based simply on the type of data they use seems to me like a bit of an over-reach as well. However, it is cool that you went through all these articles and cataloged them. It would have been interesting if you also subdivided them on what kind of tools and mathematical or mental models they used to interpret their results. How many of the WEIRD studies actually drew conclusions about genetic evolution from their datasets?

    Adam Benton · 14th March 2015 at 11:20 am

    You’re not wrong. Over the course of this research I encountered a myriad of EP ‘justifications’; and I won’t claim to have statistics about which is the most popular. However, at the end of the day the net result was the same. With a few exceptions, they all contained a justification for the use of WEIRD research. Whether it was genetics, adaptive lag etc. So when writing the post I tried to keep things simple and discuss one.

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