Evolutionary Psychology (EP) is controversial, there is no doubt, and a lot of criticism is fairly solid; it is also an intriguing and prolific source of click-baits, spurring equal amounts of excitement and criticism both in the professional and popular spheres. I’m obviously very interested in the subject, and have a well-defined opinion on the discipline as a whole:
Yes, you can always make up an evolutionary explanation for any behaviour, bias or inclination. It takes 30 seconds to imagine one, it’s fun, and dangerously difficult to substantiate it. This makes EP a tricky discipline, it is highly volatile and always at risk of becoming a sort of self-referential pseudoscientific field. However, I can’t see how our efforts to understand psychology, cognition and social interactions may aspire to produce meaningful results without taking evolution into account. At the very least, evolutionary considerations should be always used to constrain the range of possible hypotheses: if what you are proposing doesn’t make any evolutionary sense, then it’s likely that your hypothesis is downright wrong (exceptions are always possible, of course). On this, I’m 100% with Darren Burke when he provocatively asks “Why isn’t everyone an evolutionary psychologist?” (Open Access: full text via link, citation below). Therefore, much of the task of people like me (actively interested, but not actively doing research) boils down to the effort of finding and digesting good examples of EP research, and possibly promote it, or at least praise it whenever possible.
In this post, we’ll see a recent (and quite popular) example of what I consider solid EP; I will also raise a couple of points on the evolution of Righteous Indignation (see my previous post on this, with examples of EP theories that I do not like too much). To be precise, I will comment on the evolution of the sense of fairness, something that I believe is necessary to ignite Righteous Indignation (I will not explore the relation between the two concepts).
If you follow science news, you probably have heard of this already: capuchin monkeys, as well as other primates, get angry when the reward they get is manifestly unfair (compared to what their pals get for completing the same task), this isn’t exactly news, as it was reported in Brosnan and de Waal (2003 – paywalled, citation is below), but it recently surfaced again as the same authors published a review on Science (Brosnan and de Waal, 2014 – paywalled, citation is below). You can read a short commentary here, on which I’ll base my reflections.
[See it yourself: Excerpt from Frans de Waal’s TED Talk, the monkeys appear at 1:20]
The first thing to note here is that (for once!) we are not talking about a single study that got reported on the news because its results are surprising and/or bound to tickle the curiosity of the general public. This time we are commenting on a substantial amount of work, all pointing in one clear direction: what I call Righteous Indignation has a clear evolutionary origin, and similar emotions can be recognised in at least a wide range of social primates (if you are a pet owner, you probably believe that the same basic mechanism is also present in cats and dogs). This is the kind of EP that I’d like to see more of: if you want to make claims about the source of a given human trait, you’d better start looking for its origins in our close relatives, make and verify predictions on possible evolutionary homology, analogy, consider the possibility of convergence, and so forth. In other words, EP at its best is never anthropocentric: since it is almost impossible to test evolution with lab experiments, the obvious way to avoid constructing “just so” stories is to look for confirmatory evidence across the field, and this naturally means other species, whenever possible.
[As a side note, the other major alarm bells include:
– Psychological experiments that don’t explain how volunteers were recruited, this typically means “cash-starved students from the university of one of the authors”, hardly a representative sample of the human species.
– Single studies that have just been published: as we know, there is a dire need of replication (but see also: Lieberman on Edge and the excellent reaction by Neuroskeptic. Plus, of course, never forget Ioannidis “Why Most Published Research Findings Are False“). Freshly pressed studies didn’t have the chance of being reviewed by the larger scientific community, let alone replicated.]
The other reflections are far more technical, and stem from the following quote from Brosnan:
“Giving up an outcome that benefits you in order to gain long-term benefits from the relationship requires not only an ability to think about the future, but also the self-control to turn down a reward. These both require a lot of cognitive control. Therefore, we hypothesize that lots of species respond negatively to getting less than a partner, which is the first step in the evolution of fairness, but only a few species are able to make the leap to this second step, which leads to a true sense of fairness.”
At face value, this hypothesis seems absolutely flawless, but I nevertheless find it puzzling. In my direct experience, when humans are on the convenient side of an unfair deal they react in two ways:
1. At gut level, we perceive the unfairness (alert: this comes from introspection!), even when we are on the advantageous side of the deal.
2. Cognitively, we may respond to this perception, and we could decide to rebalance the deal, try to hide the imbalance, ignore it, find a justification, etc.
Seems legit? Maybe, but my point 1. is problematic: could it be that since we (humans and closest relatives) can cognitively understand the long-term implications of unfairness (roughly my point 2. above), we placed ourselves in the position to make the Baldwin effect happen?
The Baldwin effect is an old idea, interesting, controversial and very difficult to verify empirically. In a nutshell, it stands for the following mechanism: take a given species that has a certain amount of phenotypic plasticity (individuals can adapt to incidental circumstances, behaviourally or otherwise), when a new and sufficiently stable situation is established, individuals will exploit their plasticity to adapt to the new circumstances. This fact (in itself!) generates a new (secondary?) selective pressure, specifically because the individual plasticity allows a given number of individuals to exploit a new ecological niche. Under these circumstances, natural selection will be able to positively select individuals that are genetically predisposed for the new environment, establishing a surprising chain of events: new circumstances -> individual adaptation -> genetic adaptation. It’s a sort of secondary implementation of Lamarckism (!) that can be interpreted in at least two ways. At face level, it suggests that individual adaptability speeds up evolution, but to me, it’s more about the self-limiting properties of individual adaptability. I should probably write an entire essay on the subject, but the basic hunch is as follows: the genetic adaptations made possible by the Baldwin effect tend to reproduce the original individual and plastic adaptation at the genetic level; but since the individual adaptations were possible because of the (genetically encoded) plasticity of individuals, the establishment of the new genetically encoded trait is, by necessity, reducing the original plasticity!
Going back to the original subject: humans can undoubtedly understand the long-term implications of unfairness, and individuals can decide to re-balance unfair deals even when they would otherwise get the direct benefits and may thus exploit the more beneficial and long-lasting collaborations. This could be the first (individual) adaptation in the Baldwinistic chain of events (as Brosnan seem to suggest). As such, this mechanism may promote the emergence of a genetically encoded preference towards fairness (accounted here in my point 1., the gut feeling). In other words, once we accept the existence of the gut feeling reaction (and assume it is congenital) the chain of events proposed by Brosnan looks like a text-book implementation of the Baldwin effect. The problem is that I’m not so sure: accepting this interpretation requires to infer that the great apes (or some direct ancestor of theirs) are able to cognitively grasp the benefits of long-term collaboration, and consciously (!) choose to forego long-term exploitation. I’ve said that humans can do this, but I must also admit that a fair number of people are specifically unable to act accordingly (I can see a fair amount of systematic and long-lasting exploitation in society as a whole). Therefore I find the idea that other primates are consistently able to outsmart humans a little weak (possible, but doesn’t look likely). As a result, the interpretation offered by Brosnan feels somewhat unconvincing, and would like to propose an alternative sequence of events.
To do so, I first need to reconsider my position expressed in a previous post. I have (hastily/stupidly) suggested that: hierarchies are ubiquitous, as newly born mammals are pre-programmed to follow the lead of their parents. Therefore RI finds its initial selective pressure already inside the typical family structure, where siblings compete for the favours of their parents. This may not be entirely wrong, but I have no doubt that Brosnan has a point when he speculates that an important tipping point is reached when collaborative networks start to regularly extend beyond the circle of genetic relations.
Accounting for Brosnan’s observation, my updated/extended sequence of events becomes:
I) Members of a social species collaborate extensively, but collaborations do not routinely extend to non-relatives.
II) This establishes the need for individuals to protect themselves against systematic unfairness. The specular, selfless reaction is not particularly useful at this stage, due to considerations on inclusive fitness (skipped, as they would require a full-length post).
III) Classic evolution operates and leads to an innate sense of fairness, instantiated initially as a negative reaction to damaging deals.
IV) Sociality and collaboration evolve, and start including non-relatives. This presumably is mirrored with an increase of cognitive functions such as better theory of mind and related abilities.
V) The initial sense of fairness is available for extension, and at the same time, its pre-existence generates a selective pressure: because of III, individuals that get the low side of a deal react defensively, jeopardising long-term collaborations. This causes a selective advantage that favours the individuals that act fairly.
VI) The new selective pressure establishes an extension of III, allowing individuals to re-balance deals even when this requires renouncing to their own (unfair) advantage.
VII) Eventually, human cognition catches up, and reaches the level that allows us to (occasionally and) rationally understand why the VI strategy makes sense.
A few final observations:
- Yes, you (my readers) are allowed to accuse me of proposing yet another “just so” story. But still, if you disagree, I’d appreciate hearing a more elaborate explanation. Note also that the sequence above does seem to justify the available evidence, both in terms of observed differences between species and in terms of how evolutions typically operates (incrementally).
- My alternative explanation categorically excludes the Baldwin effect, but I admit (and somewhat expect) that the whole chain may be mixed up a little bit. Biology is messy, so it could be that elements of VII started appearing earlier on, peppering the sequence with some Baldwinistic contributions along the way.
- This whole reflection serves as a reminder: it’s hard to reach solid conclusions! The interpretation offered by Brosnan may be entirely correct, as may be mine, and anything in between (most likely?). It’s no surprise that the Baldwin effect remains controversial: this stuff is hard to explore rationally and even harder to verify empirically.
Burke D. (2014). Why isn’t everyone an evolutionary psychologist?, Frontiers in Psychology, 5 DOI: http://dx.doi.org/10.3389/fpsyg.2014.00910
Brosnan S.F. & de Waal F.B.M. (2003). Monkeys reject unequal pay, Nature, 425 (6955) 297-299. DOI: http://dx.doi.org/10.1038/nature01963
Brosnan S.F. & . de Waal F.B.M. (2014). Evolution of responses to (un)fairness, Science, DOI: http://dx.doi.org/10.1126/science.1251776
Ioannidis J.P.A. (2005). Why Most Published Research Findings Are False, PLoS Medicine, 2 (8) e124. DOI: http://dx.doi.org/10.1371/journal.pmed.0020124