When we ask the question of whether something is "nature or nurture", we are implicitly suggesting a dichotomy, or excluded middle - it is either nature, or nurture, or a mix of both, but not a mix of both plus something else. In The Hidden Half, Michael Blastland takes us on a journey of skepticism which somehow magically reveals the presence not only of a "third factor", but shows, startlingly, that such a factor has been known to account for as much as half (!) of the variation in some traits. References to dark matter immediately spring to mind.

After reflecting on a paradigm-shifting species of parthenogenic crayfish, the author discusses, among other things, how you only have a 50% chance of developing the same mental disorder as your identical twin you were raised with is already suffering from (shared genes and environment, remember - shouldn't this be close to 100%?); the mysterious inability to transfer infant mortality reduction measures to new regions; and the still inexplicable sudden drop in teenage pregnancies in the UK around 2008.

One could see Blastland as occupying allied but opposite territory to the human irrationality parade, spearheaded by the likes of Daniel Kahneman and Dan Ariely. Blastland contends that yes, we do misunderstand the world a lot, but rather than focusing on the human weaknesses of irrationality, he draws our attention to the fact that the world is just really, really, intractably hard to understand. In that sense, you could see him loosely affiliated with Nassim Taleb.

Another way of seeing Blastland is as a voice (however inadvertantly) in the incredibly important but widely ignored literature on transfer of learning. I covered Robert Haskell's book on the topic recently, and one of the central messages was that people don't seem to be very good at transfer of learning. Blastland's position would be that the world is not very amenable to transfer of learning. Again, it's not people's fault, the world just is that way.

This book came as a powerful message to me on the limits of human knowledge (relevant to the enterprise of this podcast) and an alternative view on human irrationality and transfer of learning (relevant to its content). I would like to get a picture of a marmokrebs crayfish and put it in a frame on my desk, so that I never forget the book's central message.

Enjoy the episode.

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