D: Oh, Yaël, I always eat too much at Thanksgiving dinner.

Y: That’s not really surprising, Don. I do too. There’s even a scientific study that demonstrates that people eat more when they eat with family and friends.

D: Really? Tell me about it.

Y: The study was done by a team of researchers from the United Kingdom and Australia, and they published their results in 2019. The researchers pooled the results of forty-two other studies of social eating, covering thousands of people as subjects. They found that, on average, people ate forty-eight percent more food when dining with friends and family than when dining alone.

D: What about when they ate with strangers?

Y: No, the effect wasn’t observed when eating with strangers. The researchers think that this is because we want to make a good impression on strangers, and so take smaller portions. This is especially the case for women eating with men.

D: I wonder why it is that people eat more when they eat together.

Y: It could just be that people eat more because meals tend to last longer when people eat together, but the researchers think there’s more to it than that. The behavior isn’t unique to humans. Some other kinds of animals, including rats, chickens, and gerbils have been shown to eat more when they eat together in groups. Our ancestors probably shared food. When eating shared food together there is a tension between the goal of being seen to engage in altruistic sharing, and getting a good meal for oneself. The solution is to consume at least as much as others in the group.