I am a huge NPR fan, or perhaps, more like an NPR junkie of sorts. If I’m home, NPR is on the radio as my background noise.
One of the programs I really like is Shankar Vedantam’s Hidden Brain. This morning he was talking about a study on stress that found that people who dance together, with the same choreography, have a reduction in their perception of pain, as well as reduced stress. Neat stuff. The report was based on a study published in the journal Evolution and Human Behavior by Bronwyn Tarr, Jacques Launay, and Robin I.M. Dunbar (article’s title is, “Silent disco: dancing in synchrony leads to elevated pain thresholds and social closeness”)
One thing in particular in Vendantam’s reporting caught my ear, and that was the language he used to describe evolution, and specifically selection for a particular trait.
Near the end of the short report, Vedantam says, “When experiences feel good, that’s usually a signal that they have served some kind of evolutionary purpose. So the brain evolved to find certain kinds of food tasty because eating those foods had survival value for our ancestors.“
People use this kind of framing all the time, but I think it leads to a misunderstanding of evolution because it is backwards. The brain didn’t evolve itself a new characteristic in order to do better at the natural selection game.
Instead, there is naturally occuring variation in a population because mistakes are made in DNA replication during the process of reproduction (i.e., when sperm and egg cells are made).
If one variant leads to a behavior or a response that leads to the individual having more or healthier offspring compared to individuals who don’t have that variant, then over time, that variant will become more and more common.
The more accurate way to have said the second sentence would be, “People who got a psychological bump from eating foods that are particularly healthy tended to eat more healthy food. In the long-run, they were healthier and ended up with either healthier offspring, or more of them, or both. Over time, the genetic mechanism that underlies the psychological boost will have increased in frequency in the population as a consequence.”
Wordy, I know. But that’s evolution. There isn’t any intentional directionality to it.