Depression is an evolutionary conundrum. On the one hand, it’s the leading cause of disability worldwide; on the other, the genes that give rise to it have been around at least as long as modern humans have walked the Earth. That means it must play a role in our survival, though scientists don’t know what. Now, bringing them closer to the answer is a new, equally perplexing study showing that depression might be linked to navigating the social world.
There’s no one gene that can predict depression, [researcher Xenia] Gonda explains to Inverse, but her research explains the role of one important gene — the serotonin transporter gene 5-HTTLPR— to tell a bigger story about how depression may have survived over the years. This strange single gene seems to play two roles over the course of a person’s life.
In youth, it appears to help people navigate and protect themselves from stressful social environments. In adulthood, it turns its back and makes financial stress even more difficult to deal with.
…[E]volutionarily speaking this gene is useful for survival at the age when humans have babies, which is why it kept getting passed on through the generations. Its ill effects don’t kick in until people are a little older, at which point it doesn’t matter as much in an evolutionary sense.
Read full, original post: Scientists Narrow Down a Reason Why Depression Survived Evolution