Is there any other organism than ourselves who can perform transactions (services or goods)? originally appeared on Quora, the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google Plus.

Mutualism - the exchange of services or goods between one species and another - is the rule, not the exception, in biology. Few organisms - most certainly not humans - could exist in a biological desert devoid of all organisms but themselves.

Plants produce oxygen that animals use to oxidize carbohydrates to produce carbon dioxide that plants use to produce carbohydrates. Insects and birds fertilize plants and spread their seeds in exchange for food. Microbes in our guts produce vitamins and other nutrients in exchange for shelter and food. Bacteria in the soil and other environments constantly exchange nutrients, metabolites and various chemical signals and controls. They are so dependent on one another that very few - about 1% - can be grown in isolation.

Those are general examples. For some more particular and amazing specific examples, I suggest you check out the “Mutualism of the Month” feature at Feed the Data Monster. This month’s example is of damselfish that farm algae in coral reefs. Other stories examine ants that protect trees, bacteria that produce protective toxins for pufferfish, sponges that shelter clams and feed off their exhaust.

From Mutualism of the Month: Tetrodotoxin-producing bacteria and their many hosts.

A few organisms - all of which are bacteria or archaea - can, in principle, live without an exchange of goods and services from other organisms. Known as chemoautotrophs and photoautotrophs, they take carbon dioxide, inorganic compounds and (for photoautotrophs) light energy from the environment and synthesize all the compounds they need to in order to grow. But they tend to live only in extreme environments, such as hot springs and deep sea vents.

Mutualism is the rule in biology because it creates virtuous cycles. Trees that produce delicious fruits will have their seeds spread more widely (and be provided with fertilizer) by birds. Birds who eat these fruits will better survive and reproduce and their offspring will spread more fruit seeds, leading to more trees and then more birds and then more trees…

The only thing that humans have invented with regard to mutualism is the concept of contracts. But otherwise, we are just another species that provides and consumes goods and services from the other species around and within us.

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