The best-known examples are probably insects, with many species of leaf-cutter ant and termites known to farm strains of fungi as a food source. It has been assumed (although I’m not sure on what basis, since farming activity would presumably be invisible to the fossil record) that these insects developed their sophisticated social structures, including caste systems, prior to the adoption of farming. This is the direct reverse of the earliest human farmers, wherein the earliest cities of the Near East, for example, arose after livestock domestication. It’s difficult to see how insects started the process and raises the interesting question of whether it offers the farming species any superiority over non-farmers of similar genera. After all, in human cultures it appears that early farmers had to work far harder for their daily bread than the gatherer-hunters who preceded them, the latter being a way of life that continues in isolated pockets even to this day. So it may not be an improvement on non-farming lifestyles - just different. Another nail in the coffin for any followers of the Victorian notion of progress…
Staying with insects, a diverse group of over three thousand beetles cultivate the ambrosia fungus for food, in a relationship thought to stretch back tens of millions of years. Unlike ants and termites, these beetle species do not all live in large, strictly-organised colonies. Heading for wetter environments, marsh snails have also been found to cultivate fungus that is ‘sown’ from spores embedded in their own excrement! Then in the water itself, some species of damselfish farm algae on the remnants of coral they have themselves killed, a process that bares a striking resemblance to Amazonian deforestation for cattle ranching. Unfortunately, the fishing by humans of damselfish predators has had the effect of aiding the population of fishy farmers and thus only increased the rate of coral loss.
Finally, the pastoralist in the pack, our everyday common or garden ant. In a bizarre simulcrum of dairy farming, some ant species control, supervise and ‘milk’ aphids. Had the species involved been more cuddly (i.e. one of us mammals) then it might have seemed all the more astonishing – a real-life antidote to Beatrix Potter-esque anthropomorphism. As it is these genuine animal farmers, with individual brains weighing a few thousandths of a gram, will drug aphids, protect them from predators and bad weather, and even use biochemicals to affect their growth patterns. And all in return for the honeydew they extract from the aphids.
You may have noticed the use of very human activities in these descriptions: domestication; caste systems; protection, etc. We are only just beginning to understand the behavioural diversity to found amongst other species, only to find we are continuously removing yet more barriers that differentiate ourselves from the rest of the biosphere. It is tempting to suggest this last example of animal farmers includes a form of slavery, with drug-controlled drones and just a whif of Brave New World. If these examples of non-human farmers were found on another planet, would we possibly consider it to be a sign, incredibly alien to be sure, of intelligence? Clearly, the brain size of the individuals involved doesn’t count for much, but a colony of 40,000 ants has the collective number of brain cells of one human. If the ants were able to store information in chemical signatures, something akin to a library, then wouldn’t this be a form of hive mind? Speculative nonsense of course, but does anyone remember the 1970’s film Phase IV?
It’s difficult to be anything other than dumbfounded as we learn more about animal behaviour, especially at what seems to be a programmed/non-conscious level. If the permutations are like this on Earth, the possibilities on other worlds are seemingly limitless. Again, this questions whether we could even recognise whether another species is intelligent or not. Perhaps Douglas Adams put it best: "Man has always assumed that he was more intelligent than dolphins because he had achieved so much...the wheel, New York, wars and so on...while all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man...for precisely the same reason."
Enough said!
