In the social sciences, unintended consequences is a term used to describe an unexpected positive or negative effect of a particular action. This is obviously the wrong word to use in the context of evolutionary systems but I am looking for something that has a similar concept. It may be related to concepts in dynamical systems theory.

For example, if we look at one trait or a group of traits, we may be able to see how this adaptation benefited a population. However, the mutations that occurred along the way would no doubt alter other systems/properties of the organism. In many cases these effects would be negligible. I am looking for any cases where the effect of one set of adaptation leads to another comparably impactful (either positive or negative) effect for the population.

The following is more theoretical and controversial but I am particularly interested in larger, more complex traits such as behavior (which may be considered the product of many different evolutionary adaptations and molecular changes) and any "unintended consequences" that could occur as a result of such a behavior. For example, empathy may be considered a very complex trait that has an evolutionary advantage (post hoc we might say it evolved because it allows specific kinds of communication in social groups) but it may also cause populations to react incorrectly (with regards to survival) in threatening situations when an empathetic response is not the most optimal response. I realize I am treading in vague territory here and it may be controversial to reduce empathy down to the molecular level as I have done in this example. But if there is any work at least related to this idea on a basic level I would be interested.

In summary, I am looking for either the term that describes this sort of analysis, if it exists, or some major examples that may help me do further research on the topic.

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    $\begingroup$ There is a lot of text here. I have tried to answer the question "Where has a seemingly beneficial/detrimental evolutionary change had the seemingly opposite affect?" $\endgroup$
    – James
    Commented Aug 22, 2016 at 5:11
  • $\begingroup$ You have addressed my question correctly. There is a lot of text because I wanted to make sure I was clearly stating what kind of answer I was looking for. Sorry if this made it more confusing. $\endgroup$
    – syntonicC
    Commented Aug 22, 2016 at 5:17
  • $\begingroup$ I get what you are trying to say, but want to point out that the terminology is poor - there are no intended or unintended evolutionary consequences of mutation, evolution is a random process, not driven by intentions $\endgroup$
    – rg255
    Commented Aug 23, 2016 at 7:12
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    $\begingroup$ Slightly more tangentially, you might also enjoy reading about the Baldwin effect in this context. In particular, since you mentioned dynamical systems, you might like Geoffrey Hinton's famous model of it. (That's the same Geoffrey Hinton who's now very famous in the field of deep learning.) $\endgroup$
    – N. Virgo
    Commented Oct 22, 2016 at 4:22
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    $\begingroup$ There is also a field of research from the 90s called "adaptive dynamics" which gets pretty directly at the kind of thing you're talking about, where an evolutionary response is not the optimal one. In fact they claim that in particular ecological contexts a species can end up at a fitness minimum instead of a maximum, and that this can lead to speciation. Those papers tend to be quite impenetrably mathematical, but if your background is dynamical systems that might not be a problem for you. $\endgroup$
    – N. Virgo
    Commented Oct 22, 2016 at 4:27

1 Answer 1



Evolutionary systems do not have these exact terms as far as I'm aware (although I'm not a behavioral expert) This mainly is because generally speaking we must stop thinking about traits in terms of "advantageous" or "intentional consequences" when discussing evolution. However there are countless examples where a seemingly detrimental evolutionary trait flourishes, or when a seemingly beneficial trait can be exploited by other species. Here I point out two simple, well known examples that might be what you're looking for.

Physiological disease trait emerges

The most well known is sickle cell anemia (SCA); a disease that also reduces susceptibility to malaria. In areas of the world with high instances of malaria, there are also high instances of SCA (Piel et al 2010).

Behavioral altruistic trait exploited

For behavioral studies I think humans would be too vague... (okay, I know very little about sociology) But there is one story that springs to mind from another animal. Birds are ideal models for behavioral studies.

The cuckoo and warbler are an endless evolutionary arms race in terms of camouflage and behavior. The cuckoo parasitises the nest of the warbler with a single egg in a clutch of 3 or so warbler eggs. The warbler parents will watch the newly born cuckoo kick the other eggs out of the nest, and then continue to feed the cuckoo chick thinking it is their own. The reason is thought to be because the warblers respond to the feeding call of their chicks (altruistic, albeit from parent to chick), however the cuckoo chick can mimic this call much more intensely than an entire brood of warbler chicks (altruism is exploited)(Davies et al 1998). By the end, the tired parents are feeding a chick three times their size.

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