Nature's magic Book

- Natural Selection and Social Theory is a collection of Triver's most impactful papers, and all together, they're quite impressive. Trivers made foundational contributions to sociobiology and evolutionary biology and his papers are a joy to read.


- He writes eloquently on the mystery of cleaning symbiotes, small fish that dart fearlessly into the jaws of their hosts, cleaning off parasites to feed themselves. He has a beautiful way of demonstrating the puzzle he's aiming at: why don't hosts eat their cleaning symbiotes after they've been cleaned? Why have the host fish evolved sophisticated warning signals to communicate to cleaners when they'll close their mouth? Kin selection can explain kin-targeted altruism, but not altruism between two different species.


- He lays out a number of ecological factors that make this kind of reciprocal arrangement possible, and begins to sound quite like an economist in the process. Three factors are key: the repeated interactions between specific hosts/cleaners, the cost of searching for a new cleaner, and the benefits both parties get from the arrangement. All together, this has allowed natural selection to shape host and cleaner into arrangements that resemble that of a businessman and his long-time shoe-shiner.


- The book is replete with plausible explanations for many wondrous natural phenomena, from warning calls to weaning conflict to the logic of self-deception. Trivers mixes clever mental models and experimental evidence, and the end result is quite accessible, though when he gets deep into the thickets of selection in ant colonies, it gets tricky. The closer he sticks to model organisms and experimental evidence, the more firm his conclusions seem-- as he admits throughout, the sections on evolutionary psychology are more speculative, less amenable to firm experimental conclusion.


- This is a moderate weakness of the book, made less serious by its publication date. It has been about 40 years since Trivers did much of his work and in the last 10 or so, there has been a growing recognition by psychologists that much of the social psych opus was riddled with error (see: Replication Crisis). Though I'm no expert, I've kept up with the evo psych literature enough to know they have some similar problems. Most of the literature on female sexual preferences changing through a menstrual cycle seems to be noise. Digit ratios as markers of hormone exposure seem to be similarly shaky. Fluctuating Asymmetry seems to have held up a bit better, but I'm not up to date enough to know.


- So I would take much of the sections on human psychology as entertaining speculation, though the existence of self-deception seems obviously true. Overall 4/5.