Anything We Can Do Ants Can Do Better

Art by Aparna Ghosh.

In comparison to many other species, humans are at a physical disadvantage – we have no ferocious claws with which to kill our prey, we are easily outrun by many other members of the animal kingdom, and the little hair on our bodies provides poor insulation against the cold. However, these physical flaws do not worry us, because, as a species, we humans pride ourselves on our creativity, our inventiveness and our ability to solve complex problems. Our ancestors’ development of agriculture 10,000 years ago represents the pinnacle of human ingenuity, allowing us to move away from an uncertain, nomadic hunter-gatherer lifestyle to a much more sophisticated and reliable farming lifestyle. We overcame the problems associated with living in a nutrient-poor world without physical and behavioural adaptations such as hibernation or migration. Instead we used our brains: rather than going out into the unpredictable wild to source our food, we made our food dependent on us. Most people believe that humans are different and special because we can solve these kinds of complex problems, but what they do not realise is that we are not alone in our agricultural endeavours…

It is estimated that ants have been farming in their subterranean lairs for over 50 million years – making the meagre 10,000 year human effort pale by comparison. Leafcutter ants (belonging to the Atta genus) are master fungal cultivators – contrary to popular belief the leaves that they carry are not eaten by the ants themselves, but are broken down into fertilisers for their fungal crops. Leafcutter ants live in huge colonies with up to 10 million workers subdivided into distinct castes, each with their own special task to complete. One of these worker castes clears land just below the surface in order to create up to 500 “gardens” where they can then cultivate their chosen fungal species. Larger workers collect vegetative matter which is then broken down by smaller workers into a paste which is smeared over the fungal crop as a form of fertiliser. If a particular strand of fungus (known as a hypha) is struggling to grow then it will be removed and replanted in a new “garden” that has been specially seeded with fertilising paste.

The parallels between human crop cultivation and ant fungal cultivation are truly astounding. Many fungal cultivars exploited by ants have been selected to be infertile, as ants reseed individual hyphae with desirable traits before they have a chance to sexually reproduce. Production of sex cells becomes redundant in cultivated fungal species and is therefore selected against. This means that fungi grown in ant colonies are all genetically identical and that ants are able to select for beneficial traits in their crops that will increase nutrient output relative to the energy that they have to invest. Selection for infertility ensures that these beneficial traits are not lost from the population, but the fungal cultivars are no longer able to exist in isolation – the same situation is true for nearly all of the world’s major human crops.

This is all well and good, but we clever humans have surely gone one step further? We have devised cunning ways to increase crop yields by inventing nitrogen based fertilisers that allow plants to grow in nutrient poor soils, we use pesticides to reduce crop damage, and we grow in monoculture and prevent soil degradation through crop rotation.

But anything we have done ants have done better!

It is clear that leafcutter ants are expert fertiliser producers but many species of Atta have also been shown to harbour bacterial colonies of the Pseudonocardia genus. These bacteria secrete an antibiotic which is lethal to many parasites of fungi. Workers of leafcutter ant colonies spread these bacterial secretions on to their fungal “gardens” in order to protect their crops against infection. Ants will also weed their gardens in order to make sure that there are no other fungal or plant species in the area that will compete with their crop for resources – they are effectively growing fungi in monoculture. Lastly, ants have been shown to regularly change the fungal species that they are cultivating, akin to human crop rotation. Different fungal and plant species have different nutritional requirements and will therefore affect the soils on which they are grown in different ways. By rotating crops, the rate at which the nutrients are removed from the soil is decreased and the area remains cultivatable for a much longer period of time – a fact that ants cottoned onto millions of years before modern man had even evolved!

What is truly extraordinary about ants is that they are able to grow their crops much more efficiently than we are without any detrimental impacts to the environment or atmosphere. Production of nitrogen based fertiliser alone accounts for roughly 2% of annual global CO₂ emissions – not to mention the carbon costs associated with crop transportation, processing and packaging. We all know that carbon emissions have a hugely negative impact on the environment and atmosphere, with knock-on consequences for thousands of species worldwide. Ants, on the other hand, quietly go about their daily business, producing all of the food they need to feed millions of colonial workers in a carbon neutral manner that has little impact on any other species. Perhaps we have a thing or two to learn from our six-legged friends!

Not only are ants fantastic arable farmers, but they are also pretty proficient in the art of animal husbandry. Many species of ant have managed to domesticate aphids and their colonies even have specialised “milking-chambers” where they are stored. Aphids enjoy protection from the dangers of the outside world whilst ants are able to feed off honeydew, a nutrient rich sticky substance secreted from the anus of the aphid. Most aphid rearing ant colonies have castes that are dedicated to their care – they keep them clean, feed them, protect them from invaders and even secrete antibacterial compounds to prevent infection. Workers use their antennae and legs in order to massage the aphids and stimulate them to release the honeydew – much like a farmer milking a cow.

We should not undermine human achievement, but it is important for us to realise that we are not living apart from nature. Every single organism that is alive today has navigated a tricky and hostile evolutionary path which has lead to the adoption of all of the wild, wonderful and often bizarre adaptations that we come across in the biological world. The convergent evolution of farming in both ants and humans is just one example of a strategy that has proved successful in the struggle for survival – the fact is that ants are just a bit better at it than we are. But let’s not be too hard on ourselves – they did get a 49,990,000 year head start!