Ants turned into 'supersoldiers'
Ants can be programmed to become "supersoldiers", according to an international team of researchers.
All ant colonies are made up of insects of different "castes", including soldiers and workers. This team worked out how to "trick" developing ant larvae to turn into a rare and unusual supersoldier caste.
The breakthrough, the researchers say, reveals that hidden traits could be unlocked in many species.
Dr Ehab Abouheif from McGill University in Montreal led the team, which found that treating ant larvae with a hormone at a very specific time during their development turned those ants into the giant supersoldiers.
The scientists managed to achieve this in two ant species that do not "naturally" have the supersoldier caste as part of their colony.Ancestral form
End Quote Dr Ehab Abouheif McGill University
This potential is locked in place for 35 million years”
Dr Abouheif and his team studied Pheidole ants - a large group of more than 1,000 related species. Of those, there are just eight that have a so-called supersoldiers, which help protect the colony by blocking the entrance from invaders using their oversized heads.
The idea of attempting to "programme" developing ants to become these giant soldiers was triggered when Dr Abouheif noticed that another common Pheidole ant species, which does not have any supersoldiers in its colony, had a few strangely big-headed colony members.
"We were collecting [the ants] on Long Island, New York, and we noticed some monstrous-looking soldiers," Dr Abouheif said.
The apparently mutant ants looked just like the rare supersoldier caste of related species, so the scientists set out to find out what had caused them to take that form.
"We understand a lot about how these different castes are produced during development of the ant larvae," said Dr Abouheif.
When a queen lays eggs, he explained, each egg can develop into a different caste depending on the environment it is in - the temperature it develops at and the nutrition it receives. But the key to "switching" into a specific cast is controlled to a large extent by one chemical inside the eggs, which is called juvenile hormone.
"So if you treat any species at the right time in development, just with a hormone, you can induce the development of the supersoldier," explained Dr Abouheif.
"The fact that you can induce it in all these different species [that don't naturally have that caste], means that one common ancestor of all these species had [supersoldiers]."
The discovery, he went on to explain, could have far-reaching implications for how scientists would view and study evolution.
He told BBC Nature that there was a "beautiful interplay" between the developing organism and its environment.
"This ancestral potential is locked in place for 35 million years and... if you can find it, you can unleash [it]."
Nigel Franks, professor of animal behaviour and ecology at the University of Bristol, said the study involved some "beautiful developmental biology that explains some fascinating evolutionary patterns".
He added: "It's an absolutely marvellous piece of work."
Evolutionary biologist, Prof Susanne Foitzik from the Johannes Gutenberg University of Mainz in Germany was also impressed by the study.
It showed, she said, that "a trait which occurs in very few Pheidole species, might nevertheless be ancestral to all of these species and that the developmental pathway is retained in all species, but shut down in most".
Dr Abouheif now has high hopes for the light that this has shed on the mechanism of evolution. He says that unlocking desirable ancestral features could be key to breeding crop plants with higher nutritional value or even tackling the mechanisms that cause cancer.
"Who's to say that all of that crazy growth that occurs in cancer isn't the unleashing of some kind of ancestral potential," he said.
"If we could find what that was, maybe we could reverse it."