The dawn of agriculture did not rise with Neolithic humans in Mesopotamia. Or in China. Or in the Levant. No, it bloomed in the rain forests of South America some 60 million years ago. And the first farmers were humble ants.
Long before early humans cultivated wheat, barley, lentils and flax, ancient leaf cutter ants raised fungus. And like human farmers, the ants had to fend off crop pests, particularly a parasitic fungal disease.
“If the fungus dies, the ants die,” said Cameron Currie, a microbial ecologist at the University of Wisconsin-Madison.
To fight the pestilence, the ants aligned with a bacteria that produces a chemical capable of subduing the parasite. Now, Currie and his colleagues have found evidence that suggests that the partnership between ants and antimicrobial bacteria has existed for tens of millions of years. The key clues came from two 20-million-year-old ants that were discovered, trapped in amber, in the Dominican Republic.
One of the fossilized ants had specialized pockets on its head, called crypts, that are also seen on modern ants. The crypts are known to house the fungus-protecting bacteria, called actinobacteria. The other ant specimen was entombed with gas bubbles on its body, likely produced by the respiration of the actinobacteria.
“It’s kind of like the ants are walking pharmaceutical factories,” said Currie, whose study appeared in the journal Proceedings of the National Academy of Sciences. “This indicates that, like in the way ants predated us in growing crops, they also predated us by tens of millions of years in associating with microbes to produce antibiotics.”
Gene editing creates bigger ground-cherry
The ground-cherry might look at first like a purely ornamental plant. A member of the genus Physalis, it bears papery, heart-shaped husks that resemble Chinese lanterns. Within each ground-cherry casing is a small, tart, edible fruit.
The fruit, related to tomatoes, might be more common in supermarkets were it not so difficult to grow in large quantities. Ground-cherry bushes sprawl untidily and can drop their fruits early, and the plants possess other undesirable traits. Diminishing these traits through selective breeding would take years.
Recently, however, a team of researchers reported that, by removing certain portions of the plant’s DNA using common gene-editing techniques, they’ve produced a ground-cherry with a larger fruit and a more ordered bush, greatly speeding the process of domestication. Their work, which appeared in the journal Nature Plants, is part of a scientific initiative called the Physalis Improvement Project.