This is fascinating:
"The planet’s land plants are engaged in an ancient alliance with the so-called “AM fungi” that grow into their roots. One plant might be colonised by many fungi, and a single fungus could connect up to many plants. The fungi harvest nutrients like phosphorus and nitrogen from the soil and channel them to their hosts. In return, the plants provide the fungi with the sugars and carbohydrates they need to grow.
This symbiotic partnership covers the planet in green. It’s common to 80 percent of land plants, and is credited with driving the evolution of this group some 470 million years ago. Now, Toby Kiers from Vrije University in Amsterdam has found that plants and fungi have maintained their grand alliance by setting up a strong market economy.
All natural coalitions are vulnerable to cheats. Any individual could withhold nutrients from one or more of its partners, benefiting from their contribution while giving nothing back. But Kiers found that at least one plant – barrel clover – can tell which of its fungal partners are giving it the short shrift, and punish the cheats by holding back on precious resources. More surprisingly, the fungi can do the same.
The result is a massive biological market. Plants and fungi both provide goods and services to one another, and individuals that don’t play their part receive little few rewards. And because both parties have a say in whom they interact with, and have many partners to choose from, neither can afford to cheat the other. The market stays competitive, and cheats don’t prosper.
Kiers discovered this by housing clovers in carbon dioxide containing a slightly heavier isotope of carbon. She could use the isotope to track the flow of carbon as it travelled into the plant, became assimilated into sugars, and flowed into the fungi.
She found that the clover sends more carbon to a species of fungus – Glomus Intraradices – that gives it plenty of nutrients in return. It’s stingier when dealing with two less cooperative (but closely related) species – G.custos and G.aggregatum. Even when Kiers inoculated a single root with different fungi, the plant could finely control the share of carbon that went to each partner."
The more we come to realize that economic behavior is simply one sort of behavior of highly evolved primates and that it is conceptually no different from other evolved behavior of other organisms, the better we'll be as economists. We are scientists who study the social behavior of a specific species of primates. We aren't defenders of some ideological faith, and we aren't philosophers. Economic behaviors are, as Carl Sagan once said, "some of the things that hydrogen atoms do given fifteen billion years of cosmic evolution. It has the sound of epic myth, but it is simply a description of the evolution of the cosmos as revealed by science in our time."