I’ve been getting a tremendous amount of pushback from Jordan Peterson cultists on this video about his ‘lobster’ claims — it’s my most popular (or should I say, unpopular) one yet. I’m seeing a lot of “context!” and “strawman!” and “he really meant to say…” and “you need to watch these 6 hours of videos to understand” kinds of comments. No one cares that his reasoning is flawed or his evidence is weak or wrong, all that matters is that he comes to the conclusion they like — they sound exactly like creationists, or Sam Harris fans. It’s more than a little ugly, and rarely have I seen a more unpleasant collection of people using poorly understood evolutionary justifications for bad science since the last time I looked at an evolutionary psychology article.
Interestingly, though, a colleague independently came to the same conclusions and made very similar arguments. He remains nameless, unfortunately, because no one wants that troop of Peterson’s baboons flinging feces at them, but he did allow his arguments to be posted.
In case you want to use this, here’s an updated write-up. You don’t need to attribute it to me (“a handsome biologist” will do) as I don’t care to engage with you-know-who’s fanbois.
The lobster (i.e., arthropod) and human (i.e., chordate) lineages did not diverge “350 million years ago”. They already existed as separate phyla by the Cambrian (~550 million years ago). Molecular divergence estimates are on the order of 800 million years ago. This error jumps out immediately to anyone with even a basic knowledge of evolutionary history.
All bilatarian animals, including all the non-social ones, have serotonin. Some plants, fungi, and amoebae produce versions of serotonin. Serotonin has several functions — in humans, most of it is found in the gastrointestinal tract. It’s not particularly surprising that lobsters and humans both use serotonin as a neurotransmitter, nor that this would be involved in the neurobiology of any particular behavioural system. There are only so many neurotransmitters, and it is pretty likely that any innate behavioural system is going to evolve to be regulated by the same basic ones. Social hierarchies are almost surely examples of homoplasy across phyla, as is the co-option of serotonin in affecting various behavioural systems.
That anti-depressants “work on lobsters” is not very surprising given the pharmacology of serotonin reuptake inhibitors, which we might expect to work on any neurons that use serotonin as a neurotransmitter. This does not imply that the neural systems of lobsters and humans are especially similar beyond this, however. For one, lobsters don’t even have brains in the same sense as vertebrates. We share some superficial similarities in neural biochemistry (as do pretty much all animals), that’s about all.
Leaving aside the comparison of deeply divergent lineages, there is enormous variability in social structures even among our closest primate relatives. Bonobos have promiscuous sex and matriarchy as part of theirs. The point is that even where hierarchical systems have a presumed genetic basis, this is a rather malleable trait evolutionarily and the specific forms of social hierarchies can be quite different even among species with brains that are extremely similar.
Of course, innate tendencies and genetic hardwiring are at best only part of the story in a complex, cultural primate like humans. Consider language. The physical and neural structures involved in language use are encoded genetically. Which language we learn is cultural. Social behaviour is similar. Yes, there can be genetic underpinnings based on brain chemistry, but how this manifests in a given human society may be greatly dependent on cultural influences. We could also have a culturally-driven system that is enabled because there is a neurological system that can support it. Nature via nurture and nurture via nature.
Moreover, culture can easily override genetic programming in humans — we see examples of this all the time. One of the great things about human brains and human societies is that we can overcome our most base biological impulses through a combination of personal choices and societal norms. In fact, modern society would not function were it not so.
This is an unremarkable example of convergence. Anyone with any competence and basic training in evolutionary biology would come to the same conclusion.