After the age of the dinosaurs came to an end some 65 million years ago, a ‘tribe’ of ants known to scientists as the Attini decided to give up life as hunter-gatherers and become farmers instead, according to a new genetic study.
It was an astonishing move that humans only managed to accomplish some 10,000 years ago.
The ants, native to South America, began farming fungus that grew on decomposing wood, setting off an evolutionary revolution.
About 25 million year ago, one group of fungus farmers began growing a particular fungi that produced protein-rich bulbs that proved a highly nutrious food.
This allowed ant colonies to increase in size until 15 million years ago when the leafcutter ant emerged. They feed a fully domesticated species of fungus kept in vast underground farms with fresh green leaves every day, supporting colonies number millions of individual insects.
A paper about the research, published in the journal Nature Communications, said that ants had evolved “complex societies with industrial-scale farming”.
“Farming created advanced human civilizations in just a few thousand years, producing a huge diversity of domesticated crops with improved nutrition, growth characteristics and yield,” the researchers wrote.
“Industrial-scale farming, comparable to that in humans, has evolved in only two non-human organisms, the fungus-growing ants and termites.
“However, the agricultural mutualisms of ants and termites were gradually modified by natural selection over time spans orders of magnitude longer than those associated with human agriculture.
“Social insect farmers cultivate fungi in subterranean gardens to produce edible proteins, lipids [fats] and carbohydrates through decomposition rather than the photosynthesis of most human crops.”
The researchers sequenced the ants' entire genome to come up with their estimated date for the transition from a hunter-gatherer lifestyle to farming among ants.
They said their date of about 55 to 60 million years ago was earlier than previous estimates.
Curiously the move to farming was not immediately beneficial in both ants and humans.
The farmer ants were “metabolically less efficient” than ant species with traditional diets, a situation that remained the same until the farmers improved their techniques.
“Similarly, early human farmers of loosely domesticated crops had poorer health and smaller body stature compared with … hunter–gatherers [of that time],” the researchers wrote.
“It seems reasonable, therefore, to expect that large-scale ant farming required a considerable accumulation of adaptive modifications, and that this process accelerated after crops became truly domesticated and no longer exchanged genes with free-living fungi.”
The final result was a single, all-purpose superfood that was resistant to diseases, pests and drought that the ants could produce on an industrial scale.
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