A fable is a fictional story, featuring animals or other creatures, with the purpose to deliver a moral lesson. So, what is Jordan Peterson's own take of his lobster story1? Or, in his words:
Why is all this relevant?
At this point he could say that he wants to deliver a moral lesson. But instead he goes on in science jargon:
First, we know that lobsters have been around, in one form or another, for more than 350 million years. This is a very long time. Sixty-five million years ago, there were still dinosaurs. That is the unimaginably distant past to us. To the lobsters, however, dinosaurs were the nouveau riche, who appeared and disappeared in the flow of near-eternal time. This means that dominance hierarchies have been an essentially permanent feature of the environment to which all complex life has adapted. A third of a billion years ago, brains and nervous systems were comparatively simple. Nonetheless, they already had the structure and neurochemistry necessary to process information about status and society. The importance of this fact can hardly be overstated.
Okay, he insists that lobsters living in a lobster society are scientifically relevant for humans living in a human society.
I don't mind a comparative approach in general. It can yield fruitful insights. And that's of course one of the reasons why biologist do observe and experiment on lobsters. But Jordan Peterson isn't interested in learning from comparison. He wants to make a moral point, and ignores the complex differences involved.
If Peterson wants to claim that similarities between lobsters and humans are homologues (inherited from the same ancestor) he should not refer to the time when the first lobsters appeared on earth, but rather to the time when our last common ancestor lived. And that was much earlier than 350 million years ago. And it is doubtful if this ancestor had any kind of a social life. (For an estimate of the times see also "Continual Chaos of Carnage")
Serotonin and its receptors are in fact a very general feature of animals. One could say that evolution was conservative in respect to these molecules. But a transmitter as serotonin delivers a signal. And the meaning of the signal depends on the targeted nerve cells or tissues. Whereas serotonin and its receptors might be more or less well conserved throughout the animal kingdom, the structure of the central nervous system is much less so. If you compare the nervous system of lobster and human you won't find many (if at all) homologous structures beyond the level of single cells. So it's rather disputable if the different parts of the nervous systems of lobsters and humans trigger the same behaviour in response to serotonin. And there are in fact significant differences. I could just cite a textbook, but let's take one of Peterson's references2:
In vertebrates, lowered levels of 5HT (endogenous or experimentally induced) or changes in amine neuron function that lower the effectiveness of serotonergic neurons generally correlate with increased levels of aggression (Raleigh et al. 1991, Miczek et al. 1994) whereas in invertebrates, the converse is believed to be true (Kravtiz 1988, Beltz et al. 1983, Ma et al. 1992).
Whereas Peterson's American lobsters follow an aggressive, agonistic tactic that's not the case for every other species. Different tactics are in use3:
To reach and maintain dominant rank in social hierarchy, individuals use specific tactics that include mixture of affiliative, cooperative, and aggressive behavior. The intensity of each of these behaviors depends on species, its social organization, and ecological niche. While general aggressiveness and physical strength defines position of the individual in the social hierarchy of simply organized groups, these characteristics are insufficient in communities where cooperative skills are required (Kiser et al. 2012).
Peterson must be aware of this, the quote is again from one of his own references. And I think we can safely assume that with us humans the majority lives in "communities where cooperative skills are required" instead of "simply organized groups". Peterson instead chooses to give a solely struggle-for life, competitive scenario to his readers.
Here is an example of a study on humans. The subjects had a bias to be quarrelsome. They were given tryptophan, a precursor to serotonin, which increased the serotonin level (at least in this group of quarrelsome subjects)4:
Tryptophan treatment significantly decreased quarrelsome behaviours in all participants. Agreeable behaviours were increased and dominant behaviours decreased in the men.
Another example with normal humans who were treated with an reuptake inhibitor (SSRI, which increases serotonin levels in the synaptic cleft)5:
While collaboratively solving a puzzle, SSRI-treated partners scored higher on an affiliative behavioral composite consisting of increased suggestions, decreased commands, and decreased unilateral solution attempts at week 1 of testing.
Peteron's lobster story is either the worst science I have seen since a long time. Or it is in fact a fable that is not to be taken literally, and its only purpose is to drive home a moral lesson. Take your pick.
p. s. There's an article worth reading with a similar gist by Leonor Gonçalves on The Conversation: Psychologist Jordan Peterson says lobsters help to explain why human hierarchies exist – do they?.
Jordan B. Peterson: 12 Rules for Life. Allen Lane, 2018, chapter "Rule 1". ↩
Robert Huber, Kalim Smith, Antonia Delago, Karin Isaksson and Edward A. Kravtiz: Serotonin and aggressive motivation in crustaceans: Altering the decision to retreat. Proc. Natl. Acad. Sci. USA 94 1997, p. 5939–5942. DOI: 10.1176/ajp.155.3.373 ↩
Ania Ziomkiewicz-Wichary: Serotonin and Dominance. T. K. Shackelford, V. A. Weekes-Shackelford (eds.): Encyclopedia of Evolutionary Psychological Science. Springer, 2016. DOI: 10.1007/978-3-319-16999-6_1440-1 ↩
Marije aan het Rot, Debbie S. Moskowitz, Gilbert Pinard and Simon N. Young: Social behaviour and mood in everyday life: the effects of tryptophan in quarrelsome individuials. J. Psychiatry. Neurosci. 31 2006, p. 253-262. URL: http://jpn.ca/vol31-issue4/31-4-253/ ↩
Brian Knutson, Owen M. Wolkowitz, Steve W. Cole, Theresa Chan, Elizabeth A. Moore, Ronald C. Johnson, Jan Terpstra, Rebecca A. Turner and Victor I. Reus: Selective Alteration of Personality and Social Behavior by Serotonergic Intervention. Am. J. Psychiatry. 155 1998, p. 373-379. DOI: 10.1176/ajp.155.3.373 ↩