Big Fish, Little Fish

Today’s newsletter (which I enthusiastically recommend as an excellent source of news about all branches of science) had an interesting item about social hierarchies in fish. As is so often the case with discoveries of organizing principles in nature, the research is likely to help us understand not just the particular system under examination (in this case reef colonies of gobies), but ourselves as well.

The study, led by a Dr. Marian Wong, of the ARC Centre of Excellence for Coral Reef Studies, at James Cook University, in Townsville, Queensland, followed the mating habits of a population of gobies on the Great Barrier Reef. These fish observe strict hierarchical rules for mating; only the largest female and the largest male are eligible. Others must wait, and they are surprisingly compliant about it. From the article:

In fact the subordinate fish deliberately diet – or starve themselves – in order to remain smaller than their superiors and so present no threat that might lead to their being cast out, and perishing as a result.

“Many animals have social queues in which the smaller members wait their turn before they can mate. We wanted to find out how they maintain stability in a situation where you’d expect there would be a lot of competition,” says Dr Wong.

In the case of the gobies, only the top male and top female mate, and all the other females have to wait their turn in a queue based on their size – the fishy equivalent of the barnyard pecking order.

Dr Wong found that each fish has a size difference of about 5 per cent from the one above and the one below it in the queue. If the difference in size decreases below this threshold, a challenge is on as the junior fish tries to jump the mating queue – and the superior one responds by trying to drive it out of the group.

Her fascinating discovery is that, in order to avoid constant fights and keep the social order stable, the fish seem to accept the threat of punishment – and adjust their own size in order to avoid presenting a challenge to the one above them, she says.

“Social hierarchies are very stable in these fish and in practice challenges and expulsions are extremely rare – probably because expulsion from the group and the coral reef it occupies means almost certain death to the loser.

What is interesting about this is the appearance of stable “basins of attraction” — in this instance, having to do with size — into which the system automatically sorts itself. The appearance, from random input settings, of these sorts of attractors (or perhaps “resonances” might be a better metaphor), is common among complex dynamic systems, without regard to the details of any physical substrate. The phenomenon seems, rather, to be simply a general principle of organization that can take many forms: size ratios between predators and prey, heights of trees and understory in mixed forests, interactions of planetary orbits, flow patterns of chaotic fluids and weather systems, and so forth. Whenever you have complex systems that are far from equilibrium, from stasis, interesting stable regularities simply emerge.

We humans engage in this sort of social behavior also. Hierarchies of class, of power, of social position, are extremely stable, with quite discrete levels, and people are careful, generally, to avoid flamboyant violations of etiquette that might endanger their security. What is worth noting is that although we would probably prefer to ascribe this behavior to psychological factors and conscious decision-making that are almost certainly not in the cognitive repertoire of small tropical fish, the patterns are equally evident in both species. The fact that such stable, socially enforced hierarchical ranking is common not only to practically all human cultures, throughout all of human history, but also to gobies, is yet another humbling reminder that despite all our vaunted powers of Reason, and freedom of Will — and notwithstanding our pitiable yearning to be the favored children of God, to be the celebrity performers for which the stage of Creation was built — we are really, in more ways than we would like to admit, just some middle-sized fish in a fairly small pond.

You can read the Physorg article here, and the original paper can be purchased from the Royal Society, here.

Related content from Sphere
  1. If memory serves, Townsville was also the home of the PowerPuff Girls.


  1. “yet another humbling reminder that despite all our vaunted powers of Reason, and freedom of Will […] we are really, in more ways than we would like to admit, just some middle-sized fish in a fairly small pond.”

    True, of course, but only so far. To paraphrase clumsily, ‘consciousness doth makes kings of us all’! At least, compared to Gobies, that is; although they might not care to admit it!

    Posted June 27, 2007 at 5:59 pm | Permalink
  2. Malcolm says

    Hi David, and thanks as always for visiting.

    Well, yes, you are right, of course; we are more than gobies.

    I find it more necessary to push back in one direction than the other, however; we humans seem not to suffer, as a species, from low self-esteem, and could do well with being taken down a peg or two.

    Posted June 27, 2007 at 6:09 pm | Permalink
  3. Yes, I know what you mean and of course we do share many characteristics of other organisms but, like the late, great David Stove, I am somewhat resistant to the notion that we can be reduced to just another species of animal. I am a ‘fundamentalist agnostic'(!), so whilst I am prepared to look for signs of God in the development of Mankind, I do so without much hope of discovery. However, that does not preclude the fairly obvious (to me) fact that as humans we do possess characteristics that are unique to our species and which seem to stem from our self-consciousness. Despite the best efforts of the neo-Darwinists, their convoluted explanations of why, for one example, in our species alone, a perfect stranger would risk his/her life in saving another, remain unconvincing and sometimes absurd.

    Posted June 28, 2007 at 7:10 am | Permalink
  4. Malcolm says

    Hi David,

    Oh, I completely agree that we are very special mammals, but I think that the underlying qualitative distinctions between us and our nearer cousins are due solely to the direction our evolutionary path has taken.

    I don’t at all think that evolutionary descriptions of morality are absurd, or convoluted; in fact I think they make a great deal more sense than any religious accounts. Keep in mind that the field of evolutionary psychology is only a few years old, and is, in partnership with tremendous strides in cognitive neuroscience and molecular genetics, advancing as swiftly as any area of science ever has. And even if these fields didn’t show such immense promise, the mere fact that some portions of the scientific edifice are yet unbuilt provides not the least shred of positive evidence for the existence of supernatural beings.

    It is important to keep in mind that, due to the uniquely developed human abilities you mention, social interactions play a larger role among h. sapiens than any other species, and the picture is not as simple as critics of naturalistic accounts of morality would like us to think, in order to reject it. Yes, there are soundly explicated adaptive reasons for many universal aspects of human nature, but the ocean of ideas in which our minds are marinated from birth forward plays a significant role as well.

    Posted June 28, 2007 at 10:26 am | Permalink