D: What were you like as a teenager, Yaël?
Y: I was your standard leather jacket‑wearing, school‑skipping, motorcycle‑riding teenage rebel.
Y: Well, for about a week. If I were to pick a single word to describe my teenage years, I'd pick "erratic."
D: You and worms have that in common. When they're adolescents, they're wishy‑washy and unpredictable; when they're adults, their behavior becomes much more efficient and competent. A group of scientists figured that out after testing roundworms' responses to a chemical called diacetyl, which shows up in their diets. Humans register it as "buttered popcorn smell." Scientists put the worms in a dish with a drop of diacetyl on one end, and a neutral odor on the other. Adolescent worms eventually got to the food, but they definitely took their time. The adult worms, on the other hand, made a beeline for the diacetyl. Then the scientists put the worms under microscopes to observe what their neurons were doing. They found that the pair of neurons that detects diacetyl fired only in reaction to high concentrations of diacetyl in adolescents. The adults' brains' neurons fired in response to much lower concentrations, and three other neuron pairs fired as well.
Y: So the adults' reaction is a lot more refined. Why do scientists think that is?
D: They think it's an evolutionary advantage of teenage worms to have broader preferences and be more flexible, especially when food is scarce. Adults, who have already learned which foods are available, can afford to be pickier and more focused when seeking food.
Y: Evolutionarily advantageous. I wonder what my parents would think if I tried to explain my teenage years to them that way.