Curiosity: Wasp landlords? Animals also apply the theory of Economics.

Economics seems like a purely human idea: it deals with reasoned choices made by rational people who weigh the pros and cons of every exchange. But it turns out that not only does economics show up in the animal kingdom; it's more the rule than the exception.


Here's something weird: "biological market theory" is a thing, and it's huge in the research world. The idea was first posed in 1994 by Ronald Noë and Peter Hammerstein in the journal Behavioral Ecology and Sociobiology. It answered a question that had plagued behavioral biologists for decades: if Darwinism is all about survival of the fittest, why would animals cooperate in the wild? Their answer: economics.

Previous research had focused on game theory, or the way that self-interested individuals strategize to get the most out of a situation. The most famous example of this is the prisoner's dilemma, where two crime suspects are being interrogated in separate rooms and need to choose whether to plead guilty or not guilty in order for both of them to get the least possible sentence. But Ronald Noë realized that animals weren't stuck wheeling and dealing with a single "partner"; they could shop around. If a partner cheated, lied, or took too much, they could move on to a better partner. That meant that the animal kingdom wasn't a prisoner's dilemma; it was a marketplace. That marketplace obeys the laws of supply and demand.

This plays out in all sorts of interesting ways. In 2017, a paper published in the journal Nature Communications showed that the female paper wasp acts like a shrewd landlord. She lets helper wasps move into her nest and take care of her offspring in return for shelter. But those helpers have a choice of which nest to join, and they'd rather go for nests that don't require so much work. When researchers added more nests to the field, sure enough, the female wasps were willing to accept smaller contributions from the helpers. Flood the market, and the price goes down.

A student of Noë, Redouan Bshary, found market forces deep in the ocean. The petite cleaner wrasse eats dead skin and parasites off of other fish, but not just when they're feeling peckish. It's done in a systematic way: the wrasse hangs out at a "cleaning station" on a piece of coral, and other fish visit the station when they need some polishing up. Both parties in this exchange get a choice: the wrasse can vary how gentle the cleaning is and how long the "clients" have to wait, and the clients can always choose a different station. Bshary realized that the clients came in two forms: some lived by the station and couldn't travel far beyond it, and others explored big ranges and were free to choose among many stations. Just as market theory predicted, the fish who could go elsewhere got prompter service and a gentler cleaning, while the locals had to wait longer for rougher treatment. The hazards of being a regular, am I right?

Market forces play a role in the behavior of everything from plants to primates, birds to bugs. It's a good reminder that acting in your own self-interest doesn't always turn out that way — sometimes, you have strategize and cooperate to get the best result.