Did Your Brain Evolve to Be Depressed?

An evolutionary explanation of mental illness

Dana G Smith
Elemental
Published in
4 min readFeb 9, 2021

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Credit: Image by cuppyuppycake / Getty Images

This is a modified excerpt from Inside Your Head 🧠, a weekly newsletter exploring why your brain makes you think, feel, and act the way you do, written by me, Elemental’s senior writer and a former brain scientist. Subscribe here so you won’t miss the next one.

I’m fascinated by the field of evolutionary psychology, which you can think of as the eventual landing site of virtually every line of questioning about human behavior that starts with “why.”

Why do we give gifts for holidays and birthdays? Because we’re a social species that is hardwired to express altruism in order to increase our own chances of survival. Why do humans have tribal tendencies that can span everything from sports team affiliations to race? Because our prehistoric ancestors had to make instant judgments between friend and foe in order to survive. Why do we plan fantasy vacations to Hawaii during a pandemic? Because our brains evolved to prioritize future events so that we could appropriately prepare for them and increase our odds of survival.

These are, of course, vast oversimplifications of extremely complicated concepts that have many biological and cultural contributors. But there is a sort of satisfaction and sensibility that comes from the ultimate answer of “our ancestors evolved to be this way because it helped the human species survive.”

This rationale gets tricky, however, when discussing behaviors and traits that are thought to be disadvantageous today, most notably mental illnesses like depression.

A quick test to determine whether a behavior is inherently human and potentially evolutionarily selected for is whether it can be found in multiple places and times. Depression passes this test as depressive or melancholic symptoms have been found in virtually every continent and culture, including hunter-gatherer societies, and described for thousands of years. Depression is also extremely common, by some estimates afflicting up to half of the population over the course of their lives.

This fact raises the question of whether there might be an evolutionary advantage of depression, the rationale being that the condition would otherwise have been…

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Dana G Smith
Elemental

Health and science writer • PhD in 🧠 • Words in Scientific American, STAT, The Atlantic, The Guardian • Award-winning Covid-19 coverage for Elemental