Acting for the survival of the species (a falsehood)

Spread the love

Today’s falsehood is the idea that individual animals act for the benefit of their own species.

Let me give you an example. When I was a kid, I watched a nature show about cougars. The show ‘documented’ a single female cougar going about doing cougar-things and being generally cougar-like. At one point she had cute little baby cougar kittens.

Then a flood came. The stream near her chosen lair swelled its banks and threatened to drown the kittens. So, she carried one of the kittens up the hill to a new lair. She went back to get the second kitten, and the flood waters were even higher and closer to the den, but she managed to save that second kitten. When she went back to get the third kitten, it was not at all clear that she would make it in time. It seemed inevitable that the third kitten would be carried off to it’s death by the torrent. As the mother cougar approached the flood and all hope seemed to diminish, the narrator said “The mother cougar, driven by an instinct to save her species, searched desperately for any sign of the third kitten, who represented the next generation of cougars.” (Or words to that effect.)

At the last second, the mother cougar spotted the kitten, who had already run partly up the hill, and brought it safely to the lair. (We presume that all kittens always survive, which is why we are up to our necks in cougars.)

Within biology, many of the falsehoods being discussed here actually affect practicing scientists. We’ll see an especially good example of this later with the “reproductive success is maximized by fitness” fallacy. We’ve already seen it with the “Evolution has stopped for humans” fallacy. But the “Survival of the species” fallacy never directly affects actual biologists because it is literally almost the first thing you learn about selection, evolution, organismic biology, or whole organism biology. Individuals act in their own (inclusive) self interest. The appearance of altruism is usually underlain by selfish motives. If there is any group-level selection at all (and most biologists think there is not, or at least not much) it is certainly not operating at the level of the species.

The mother cougar was not trying to save cougars when she desperately searched for the third kitten. She was, rather, doing two things simultaneously.

1) She was, at some ultimate level not cognizant to her in any way, trying to increase the likelihood of the survival of her own genes. Or, more accurately, some of the genes she carried were busy saving themselves, and for this particular event, the other genes were free-riding. During some other episode of her life, perhaps as hunger drives her to hunt, different genes are perhaps busy saving themselves while the others are free-riding. I’m sure you get the picture.


2) She was, at the more immediate, or as we like to say, proximate level, her behavior was a response to some kind of limbic and endocrine attachment syndrome whereby mothers bond to and do things for their offspring, similar to the kinds of deep neurological systems that may facilitate the orientation of offspring to their mothers, and in the case of these kittens, the neuro-muscular system that causes a kitten to go limp when picked up by the nape to be carried by mom, instead of squirming around, flying out of mom’s mouth, and dropping fatally into the rushing river.

That the saving of the individual kittens would possibly help the survival of the species is a side effect of her behavior at both the proximate and ultimate level.

This idea can be tested, and has been tested, both in theoretical constructs and in field studies. It is often possible to construct alternative testable hypotheses, one based on an instinct to help the species, or some other large group, and the other to at selfishly. Below, I recommend texts you may wish to consult for excellent overviews and evidence along these lines.

The bottom line is this: A variant of a gene (an “allele”) that confers a trait that results in group-level or species-level survival or reproduction at the expense of the individual will have lower fitness than an allele that instead confers a trait that results in individual survival or reproduction. One of the classic examples of this phenomenon is the prudential restraint in egg laying among colonial nesting birds.

Some bird species — such as gulls, terns, boobies, and the like — nest communally and from these nests forage for nearby resources to feed themselves and their growing young. So, there may be dozens, hundreds, or even thousands of gull nests on well protected cliffs overlooking the ocean, and the gulls will go down to the ocean (one member of the pair at a time, the other staying behind to protect the egg or chick from the other gulls) to feed, and bringing back food for the mate and/or offspring.

The following has been noted (slightly oversimplified here):

1) The number of eggs that a pair will have in a nest varies, let’s say from 3 to 5.
2) The number of eggs each pair has in a given year is the same, with most of the birds laying 3, 4, or 5 eggs.
3) The number of eggs, higher or lower or median, appears to vary with the availability of resources. When there are lots of resources, more eggs are laid, when resources are scarce, fewer eggs are laid, to the extent that this can be assessed by the birds.

Two different hypotheses have been proposed to explain these behaviors.

A: The birds are practicing prudential restraint for the benefit of the group. By holding back on egg laying, the demand on the local resources will be lowered now and over the near future when the offspring fledge, so there will not be as much competition for resources and more members of the group will survive. This is group selection, and taken just one step more, survival of the species.

B: Individual birds (or pairs of birds, but really, probably just the female) lay the number of eggs that matches some perception about the availability of resources, and the birds are essentially tracking the resources and producing the number of offspring that makes sense, economically/ecologically, that year.

One way to test this is to place extra eggs in a small number of nests. If only a few extra eggs are placed overall (but say one per nest), that will not measurably affect the overall availability of or competition for resources by the group, but it may severely affect the birds with the loaded-up nest. Extra egg experiments have been done, and when extra eggs are added to the nest, the final number of offspring fledged goes down rather than up. In other words, the number of eggs in an individual nest is adjusted as needed for the individual’s fitness, not the group’s fitness.

Another fact worth noting is that if both parents in these colonial nesters leave the nest alone, the neighboring birds tend to eat the eggs or chicks as a snack. So much for survival of the species. One would think that if you could prudentially restraining one’s reproduction as an evolutionary strategy, one would prudentially restrain one’s snacking behavior for the same purpose.

It is interesting to note that the survival of the species fallacy has other forms in other areas that are very important. The survival of the species problem is the same problem as the tragedy of the commons problem. It is also the same thing as the “agency effect” or the “agency problem.” It is also worth noting that the early work on this problem was tied to some of the important early work that moved theory from evolutionary biology over to economics. The economists have been playing with this kind of theory … called game theory … ever since.

ResearchBlogging.orgAn interesting paper representing the overlap between economics and evolutionary biology with respect to this issue is “Economic man and selfish genes: the implications of group selection for economic valuation and policy.” From the abstract:

A basic tenet of socio-economics is that economic behavior is shaped by social bonds and cultural context. A relevant controversy in evolutionary biology is group selection and the related issue of altruistic behavior, that is, behavior neutral or detrimental to the individual but positive for the survival of the group. In this paper we examine the parallel controversies surrounding “economic man” and “selfish genes” with particular emphasis on the policy implications of group selection. We argue for the replacement of standard welfare economics with models of human behavior in the spirit of “consilience” between economic theory and the best available science from other relevant disciplines.

(Source:Gowdy, J. (2004). Economic man and selfish genes: the implications of group selection for economic valuation and policy Journal of Socio-Economics, 33 (3), 343-358 DOI: 10.1016/j.socec.2003.12.026)

As promised, here are a few suggested readings that will cover this topic (and other topics). Most of these are available used.

Genes in Conflict: The Biology of Selfish Genetic Elements

The Selfish Gene: 30th Anniversary Edition–with a new Introduction by the Author

Sex, Evolution and Behavior

Homicide (Foundations of Human Behavior)

Social Evolution

Natural Selection and Social Theory: Selected Papers of Robert Trivers (Evolution and Cognition Series)

More Falsehoods !!!

This post is one of a series on the topic of falsehoods. The following is a list of falsehoods posts in order:

Have you read the breakthrough novel of the year? When you are done with that, try:

In Search of Sungudogo by Greg Laden, now in Kindle or Paperback
*Please note:
Links to books and other items on this page and elsewhere on Greg Ladens' blog may send you to Amazon, where I am a registered affiliate. As an Amazon Associate I earn from qualifying purchases, which helps to fund this site.

Spread the love

17 thoughts on “Acting for the survival of the species (a falsehood)

  1. While it is correct that it is a falsehood it should be noted that humans really do seem to actually sometimes act for the survival of the species as a whole. It seems to be that this is somewhat due to our instincts to help out our tribal group and we’ve just generalized our tribal groups a lot.

  2. Or, we ignore variation and randomness (using “randomness” in the modern sense of the word as teenagers use it these days) in non-human animals, but we attribute lofty motives to it when it occurs in humans.

    I’m just sayin’

  3. I know what you mean. Or people who have themselves sterilized prior to having children … the ultimate prudential restraint. Aside from any social judgments (related to “oh, that’s so random”) it just has to be understood that “non-darwinian” behavior can first be explained by the fact that in all animal systems we see lots of non-darwinian behavior. Socially, culturally, etc. we may classify that behavior any way we like, and think anything we like of it, but as long as it is below a certain (vague) level of frequency, it falls within ‘darwinian’ expectations.

  4. One example which used to be cited was the sentry bird. a bird who sits on a high branch watching for predators while the rest of the flock is feeding. Supposedly: (1)the exposed sentry bird is more vulnerable to predators, and (2) the sentry bird misses out on feeding. I think (2) has been demonstrated not to be true. I have never bought (1) because no predator is going to go for an alert bird who is shouting, “I see you.”

    I suppose the example these days would be sentry Meerkats.

  5. Jim, Sentry Meerkats are a bit different as I understand. They are more similar to bees. The meerkat clans are generally very genetically similar. So acting to help save close relatives selects for their own genes. This isn’t the same as acting to preserve species at all.

  6. Or you could use the example of people arguing against healthcare for everyone. If you can’t afford your own, why should I help you. Doesn’t exactly sound altruistic to me

  7. Thank you for writing this series!! This one was one of my favorites. For some people, it’s hard to admit that we are always just being selfish.

  8. Good one. Lately it’s all been about the polar bears. Oh, here’s another good one: mountains “thrusting up” through the earth’s crust. I once spent time explaining how it was an illusion and that erosion was what took everything but the harder pointy bits we see. Their response: “Oh, I like my description better as it captures the sacredness of creation better.” Wah!

  9. Greg, do you happen to have a ref for that Meerkat study?

    I’ve been digging through a lot of alarm calling lit recently, and group selection as the main factor is pretty much ruled out in the cases with actual data. Nepotism towards direct offspring is supported in several species… suggesting Meerkats, prairie dogs, etc might be optimizing based on a slightly broader kin selection (though I don’t know the data there).

    Sherman (1977) had a good turn of phrase: [under certain hypotheses] “alarm calls are phenotypically but not genotypically altruistic.”

    PS: Shelly & Blumstein (2005) did a phylogenetic analysis of alarm calling in a bunch of rodent species. Being diurnal is much more closely associated with alarm calling than being social. It looks like alarm calling evolved in diurnal rodents, some of which then went on to evolve sociality. Signaling “I see you” to potential predators seems like the most plausible evolutionary origin.

    PPS: The ‘cost’ of being a sentry is almost certainly not increased risk of predation for most species. However, sentries aren’t out foraging for themselves and being alert may incur some additional metabolic costs.

  10. I don’t recall where I got the idea sentry birds do not lose out on foraging. I pose the testable hypothesis that sentry birds already have full crops when they pull sentry duty.

  11. I don’t know which (if any) bird species have sentry birds while the flock is feeding. I do see mixed species feeding flocks and wonder if the various component species contibute sentrys. Is there a bird behavior student in the house?

  12. Well, let me discuss something I do know about. As a young person in the Texas Hill Coountry, during deer season, I would take my 22 and go out in the pasture deer hunting. I would go about an hour before dark, work upwind, moving very slow, making no quick motions, stopping every 10 steps or so to carefully look around. Even so, the deer would usually detect me before I saw them. One would give a loud snort, all the white tails would go up, and they were out of there. So much for deer hunting that day. Occasionally, I would be successful, and get a clear heart shot. My hunting method was not very productive, but is more fun and challenging than putting out some corn and harvesting deer from a stand.

  13. Thank you for writing this series!! This one was one of my favorites. For some people, it’s hard to admit that we are always just being selfish.

    I’m not sure how you mean this but said like this you are also speaking in a misleading or confused way. We are not “always just being selfish” in a psychological sense by any means. The issue is that the behavior that puts ourselves is neutral or risky for us while benefiting others in many cases has an evolutionary advantage that has led to our tendency to act that way being selected. But that tendency to act that way is what many of us really, genuinely, psychologically feel inclined by when we have altruistic mindsets. It’s just that the altruistic mindset was “selfishly” advantageous enough for the genes of those with that altruistic psychological mindset that that altruistic mindset has been to a certain extent selected.

    To project into a simplified evolutionary story, at some point there could have been humans who genuinely didn’t care enough to risk for others in any circumstances and those who genuinely did care enough to risk (at least in certain contexts). When the genuine desire to risk in the rights sorts of contexts (like for close kin) proved advantageous for propagating the genes of those with that genuinely felt desire and those with no feeling of desire to risk led to less successful propagation of genes, those with the genuine desire kept propagating that genuine desire. The only thing “selfish” about our normal set of evolutionarily fit altruistic inclinations is that it turned out to be to our ultimate biological advantage to have them and that that accounts for why we and not our sociopathic cousins predominate. But this does not mean that I need to know that my every altruistic inclination is *really* deep down selfish. I was bred to have the inclination because of its ultimate utility to my ancestors (and likely to me) but I still am motivated by it on a first-order level by a genuine interest in it.

    I belabor this point here .

Leave a Reply

Your email address will not be published. Required fields are marked *