Evolutionary psychiatry

Published on March 31, 2022   38 min

A selection of talks on Genetics & Epigenetics

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Hi, everyone. Randy Nesse here, with a talk about evolutionary psychiatry. I've spent most of my career as a professor of psychiatry and psychology at the University of Michigan. Six years ago I moved to Arizona State University to start the Center for Evolution in Medicine.
What is evolutionary psychiatry? It's a subsection of evolutionary medicine, and what is evolutionary medicine? It's simply using the basic science of evolutionary biology to better understand disease and to better treat patients. There's nothing alternative about it. It's just like using genetics or anatomy. The thing that's different is that we have not been using evolutionary biology either for medicine in general or for psychiatry in particular.
There are two questions to ask about a disease. The traditional one is, what's the mechanism? What's broken? How can we fix it? A whole separate question is, why does natural selection not do a better job of designing the system so it wouldn't fail? Why are we vulnerable? That's the question that is at the core of evolutionary medicine.
Why did natural selection leave us vulnerable to disease? This was the topic of a book I wrote with George Williams that got a lot of other people interested in asking that question, and here are some answers. First of all, it has limits, mutations. It can't be prevented. It can't start fresh. That's the traditional explanation for why natural selection leaves us vulnerable, but there are others. Another one is that natural selection is just too slow to protect us against things that change fast, especially pathogens that evolve fast. Nowadays, our societies evolve much faster than we can, leaving us vulnerable. Thirdly, natural selection doesn't maximize health. This is very surprising and disturbing. It maximizes reproduction, often at the expense of health. All traits are tradeoffs with costs, so nothing can be perfect in the body. This idea is that evolutionary medicine thinks everything is perfect, but the opposite says that nothing can be perfect. Finally, a lot of defensive responses like pain and fever seem like they're diseases or problems, but they're useful responses.