Continual Chaos of Carnage

Do all lobsters fight for territory and dominance? No, they don't. There are lobsters and ... lobsters. Here is what Jordan Peterson wants us to believe the world of all lobsters looks like:1

Lobsters live on the ocean floor. They need a home base down there, a range within which they hunt for prey and scavenge around for stray edible bits and pieces of whatever rains down from the continual chaos of carnage and death far above. They want somewhere secure, where the hunting and the gathering is good. They want a home.

This can present a problem, since there are many lobsters. What if two of them occupy the same territory, at the bottom of the ocean, at the same time, and both want to live there? What if there are hundreds of lobsters, all trying to make a living and raise a family, in the same crowded patch of sand and refuse?

Yeah, what if?

First, he is right (sort of). Here is an account by Huber et al.2 backing Peterson's image of the lobster world:

Intraspecific encounters among clawed decapod crustaceans are characterized by a distinct shortage of diplomatic skills. With the exception of mating behavior, most interactions are agonistic in nature, escalating until one of the combatants withdraws.

Second, he is wrong. Compare with this one:

M. quadrispina is native to deep marine waters off the west coast of North America. They live in rocky areas, often crowded together on accessible surfaces. Most wild populations are deep, making studies difficult: no reports exist, even anecdotal, of agonistic interactions in the wild.

We observed no lasting dominance hierarchies among M. quadrispina in any of the seawater tables or observation tanks. They did not have territories of any kind, and were rarely agressive towards each other. Transient agonistic interactions were always resolved without lasting effects. Dominance hierarchies did not develop and the frequency of agonistic encounters did not increase during mating periods.

Sounds a bit different. What happened? Quite simple. Antonsen & Paul3 from whose work the last quote is decided to do their research on another species, because they figured a comparison might yield some insight into the serotonin system.

The lobster most frequently used for studies is the American lobster (Homarus americanus) or maybe the European lobster (Homarus gammarus, I only mention the latter because I found a nicer picture of it.) There's plenty of easily accessible American lobsters around (and maybe the behaviour of this species fits better in certain folks world view). Munida quadrispina on the other hand is a "squad lobster", also a decapod but more distantly related to the thoroughly studied lobsters and crayfish.

Some peeps might ask now, out of which filthy closet did I dig the squad lobster. Well, it was Jordan Peterson himself who set me up to it. Because he refers to Antonsen & Paul by citation of their work. He uses them to back his claim that serotonin has an effect on posture. But he fails to communicate that it is a different species altogether and he fails to mention that there is an example of a very different lobster world than he wants us to believe in. Peterson's lobster world:

The female lobsters (who also fight hard for territory during the explicitly maternal stages of their existence) identify the top guy quickly, and become irresistibly attracted to him.

And the squad lobster world:

At least in captivity, the successful male in the competition for mates was the one who got to the receptive female first, regardless of size.

And more squad lobster custom:

Frequency of aggressive displays decreased in the presence of food. Feeding was a free-for-all, success depending less on size than on speed in grabbing a piece of food and escaping to a safe spot.

Sounds almost human to me. ;)

The ancestors of Munida quadrispina and the American lobster diverged ca. 360 million years ago4. Whereas our (the human apes) line diverged from both the decapods' ancestor line in a precambrian time. That was a time when the earth was inhabited by strange and alien metazoans, most of whose decendants haven't survived the Ediacaran. There we lose the fossil track of early proto- and deutoerostomia. Estimates go for at least 550 million years, maybe much more.

So, who wants to believe that we humans are much more like the American lobster, than this American lobster is alike his squad lobster "cousin"? Peterson states:

Lobsters have more in common with you than you might think

Well, which one of them, if at all? Antonsen and Paul:

The social structure of M. quadrispina populations differs substantially from that of crayfish: aggressive acts are rare and dominance hierarchies do not exist, whereas in populations of crayfish and American lobster, aggression and fights are common and used to establish dominance hierarchies.

It is obvious now that Jordan Peterson either doesn't read his references (bad)5 or just shows his audience what he wants them to see (worse).


  1. Jordan B. Peterson: 12 Rules for Life. Allen Lane, 2018, chapter "Rule 1". 

  2. Robert Huber, Kalim Smith Antonia Delago, Karin Isaksson, Edward Kravitz: Serotonin and aggressive motivation in crustaceans: Altering the decision to retreat. Proc. Natl. Acad. Sci. USA 94 1997, p. 5939–5942. 

  3. D. L .Antonsen and D. H. Paul: Serotonin and octopamine elicit stereotypical agonistic behaviours in the squat lobster Munida quadrispina (Anomura, Galatheidae). J. Comp. Physiol. A 181 1997, p. 501-510. 

  4. I'm not an expert on crustacean phylogeny. I estimated the time of divergence from the diagram in Megan L. Porter, Marcos Pérez-Losada, Keith A. Crandall: Model-based multi-locus estimation of decapod phylogeny. Molecular Phylogenetics and Evolution 37 2005, p. 355–369. See also http://tolweb.org/Decapoda/6308

  5. See also "Brains in Dissolution" and "Sweeping Avian Diseases".