Please, Not Another Bias! The Problem with Behavioral Economics is a transcript of a talk given by Jason Collins. In it, he discusses the link between behavioural economics and evolutionary biology. Perhaps “link” is weak – I think Collins is suggesting that behavioural economics is really a subfield of evolutionary biology.

Its a great read which raises plenty of thought provoking examples. In an attempt to crystallize my own understanding of the article, I’ll try to give you, dear reader, a concise summary of each point, and provide a little bit of critique where I found some. Let me know if I interpreted anything wrong, and please feel free to challenge me on my critiques!

Ecological rationality

When we consider common flaws in human judgement, behavioural economists call them “biases”. Gigerenzer suggests that these biases are really just the side-effects of using a decision heuristic in a situation in which the heuristic wasn’t going to work very well.

We care about this because it forces us to think critically about why we’re seeing an example of flawed human behaviour instead of simply calling it a bias and moving on.

Evolutionary rationality

Collins points out that many human propensities are inextricably linked to behaviours and objectives that are inherent to the way humans evolved. Note that if you are a human on earth today, that’s because your ancestors have survived long enough to reproduce. Surviving and reproducing is what humans do and have always done, so we can reasonably suggest that our decision making revolves to some extent around those objectives. (I have no reason to doubt then, that Collins’ behavioural economics applies to all creatures, and in fact, he uses preying mantis as an example later on.)

Of course, the modern world is very different from the one that our early ancestors lived in, so it’s no surprise that evolutionary models fail sometimes. Thanks to Gigerenzer, we ought question why these models fail, but if they do, we’ll call it mismatch.


Over and over again, Collins’ examples involve men and women and mating preferences. I wonder how evolutionary biology accounts for the spectrum of sexuality. Do the models still hold?

Regardless, Collins draws a line between men and women. Men’s reproductive patterns are dictated by nearly infinite sperm, no cost of child bearing, lower chance of child rearing (another cost) while women generally face the exact opposite case.

Thanks to these evolutionary traits, men stand to gain much higher evolutionary rewards from reproductive “success”. This leads men to go the extra mile (and take risks) when attracting a mate, which explains why skateboarding guys are more likely to hurt themselves doing ridiculous tricks in front of an attractive girl.

An attractive girl being in viewing distance is an example of ecological rationality. Skateboarders might normally decide that they would avoid going too crazy on the half-pipe, but the environment changes when a girl walks in, and the heuristic starts to fail. (I tried looking for the hot babe bias but it wasn’t there).

Present bias

This is a traditional problem that is explained simply by stating that humans overvalue present rewards and devalue future rewards, even if they are identical when the future is consistently discounted. Collins’ example is easy to understand.

If I asked: “Do you want one apple today, or two apples tomorrow?”, the answer would vary between people. But if I ask: “Do you want one apple a year from today, or two apples a year from tomorrow?”, then most people would pick two apples, even though they are exactly the same choice if we discount the one year consistently.

Collins seems to suggest (maybe not exclusively) that mating opportunities create present bias. He cites a study where men showed stronger present bias after being shown images of attractive women. He then points out the extreme example of preying mantis, whose mates decapitate them immediately after sex. The mating opportunity creates a very high present bias towards reproducing, but that makes sense because reproduction yields evolutionary rewards.

Costly signalling

This was my favourite point. Peacocks risk being noticed and eaten by virtue of having a flashy tail, so why have they evolved to keep those tails? The evolutionary reasoning is that it indicates to potential mates that they are the fittest; despite being attractive prey, they’ve survived, and that makes them fit candidates for reproduction.

Collins’ main example of human costly signalling is conspicuous consumption. Why would people ever spend ridiculous amounts of money on an impractical watch or an unreliable sports car? Its because those things are (costly) signals to potential mates. Costly signals are strong signals because they are costly – its uncommon that “unfit” individuals have the resources to waste on costly signals.

Concluding thoughts

I’m swayed by these examples, but I suspect that they were selected under the influence of confirmation bias (hehehe). I’m curious to hear examples that don’t apply to mating. I’m also wary of the “mismatch” concept, because I imagine it is hard to know how strong the evolutionary ties to a specific model are. I’m specifically wary that “mismatch” is used to blame the environment more than it is used to blame the evolutionary model, and at the end of it all, I have to admit that the evolutionary links might be a little tenuous at times.

All that said, I’d like to thank to Jason Collins for giving me a first real taste of behavioural economics and promptly superseding it with the theories of evolutionary biology.