Researchers at the Smithsonian Tropical Research Institute (STRI) in Panama and the University of Copenhagen (UCPH) in Denmark think that the choices the ants make about what to bring back to the nest may be driven by the nutritional needs of their fungus crop. They present new evidence in the journal Nature Ecology and Evolution showing that fungi become more dependent on the ants to fulfill ever more specific nutritional needs as the partnerships develop. When the pilgrims landed in America, they learned from indigenous groups to plant corn with dead fish as fertilizer. Compare that system to a huge, industrial cornfield where liquid fertilizer is applied. The modern cornfield produces more corn, but it also requires industrial-scale use of specific nutrients.
"This is what we see as these ant farmers evolved," said Jonathan Shik, former post-doctoral fellow in staff scientist's Bill Wcislo's lab at STRI and now an assistant professor at UCPH. "Atta ants evolved huge agro-industrial farms. They have giant colonies with millions of workers. But they have miniscule brains and no detectable culture, so the big question is 'How do they know exactly what their crop needs?'"
Humans first domesticated wild plants about 10,000 years ago. The attine ants are much more experienced farmers: they first domesticated fungi nearly 60 million years ago. Today, a striking diversity of agricultural practices exists among the more than 250 species in this group of ants. All of these evolutionary stages of ant crop domestication can be found in a single 20-square-meter (about 66-square-foot) plot of tropical forest leaf litter in Panama.
"Even the most primitive species of attine ants navigate a complex forest environment," Shik said. "They walk past many resources to pick up a tiny piece of insect poop that is exactly what they were looking for. They take it back to the nest and use it to grow a fungus."
The expression 'You are what you eat' points to the importance of dietary choices and the trade-offs involved in making these decisions.
"One of the things that drives the human obesity epidemic is that we are hungry for carbohydrates all the time, and we can't control ourselves when we are around fats and sugars," Shik said. "But an alternative idea called the 'protein-leverage hypothesis' is that humans have an intake target for protein, which is quite high since our ancestors evolved eating a lot more protein than we eat today. We overeat carbs because we're starved for protein. And we only stop eating when we get enough protein. My ants are also very sensitive to the amount of protein they gather." ...<<<Read The Full Article Here>>>...
