Researchers create ‘super soldier ants’
Dormant genes activated with hormone doses
They sound like monsters out of science fiction: super-soldier ants that grow to double or triple normal size, with huge oblong heads and giant vicious mandibles they use to defend their colonies from attack.
They are biological anomalies known to occur in a handful of ant species in nature as a result of environmental stresses. But now a Montreal researcher has induced the growth of super-soldiers in his lab and shown this Incredible Hulk-like potential exists in all species — including humans. In the process, Ehab Abouheif, Canada research chair in evolutionary developmental biology at Montreal’s Mcgill University, may have helped piece together a genetic puzzle.
The findings are groundbreaking for evolutionary theory, Abouheif said, because they show that dormant genes can be locked in place for millions of years, only to re-emerge as a result of environmental conditions.
“Birds with teeth, snakes with fingers, and humans with apelike hair — these are ancestral traits that pop up regularly in nature,” Abouheif explained. “But for the longest time in evolutionary theory, these ancestral traits were thought to go nowhere — slips in the developmental system that reveal things from the past.”
Now, the scientists believe these “slips” are dormant traits that are common to every member of a given species.
It’s like with the doom and gloom of global warming. As soon as you’re changing the environment, you’re unleashing this potential everywhere
EHAB ABOUHEIF
“What we’re showing is that environmental stress is important for evolution,” Abouheif said.
“Any time you have a mismatch between the normal environment of the organism and its genetic potential you can release (new characteristics) — and these things can be locked in place for 30 to 65 million years.”
The team’s findings were published in the journal Science. The research began in 2006, when Abouheif noticed super-soldier ants for the first time among a species of ant on Long Island from the genus Pheidole he had been studying for 15 years.
There are some 1,100 species of Pheidole ants, which have two castes: worker ants and soldiers. But only eight of the 1,100 species were known to produce a third caste of supersoldier in reaction to stress — mostly in regions of the Southwest U.S. and Mexico.
The discovery of the rare super-soldiers among the Long Island ants startled and intrigued abouheif. he decided to try to duplicate the emergence of the giant warriors in a laboratory setting and in other species of ant, selected randomly. By applying the growth hormone methoprene to the larvae of various Pheidole ants previously unknown to beget super-soldiers during a “narrow window” in their gestation, the ants developed a huge head and useless wings.
Abouheif said this treatment awakened the traits of militaristic ancestors who used their grotesque noggins to defend their colonies from attackers by blocking the entrance to their nests with their heads. These characteristics were suppressed as the genus became more diverse and many species developed other strategies for defence over millennia.
But what his research shows is that these genes can remain dormant for millions of years only to be reactivated under exceptional environmental conditions.
“The potential is there. It’s only under certain conditions that natural selection grabs this potential and utilizes it,” Abouheif said. “The environment can invoke and induce this.”
While the research focused on this amazing potential in the tiny ant, he said these biological anomalies exist in all species — even humans.
This was what the father of evolutionary biology Charles Darwin meant when he wrote about atavism, also known as reversionism, in his landmark treatise Origin of the Species, Abouheif said. It also had been documented in other “forgotten” research from the early 20th century: dolphins born with hind legs, humans with third nipples or tails.
“These were the freaks of nature, the Barnum and Bailey of nature,” he said. “What we’re showing for the first time is that these are also products of dormant genes.”
Human development has much in common with that of ants, Abouheif said, noting we share a copy of a gene with the critters. Both humans and ants are “social,” he said, and “take care of their less fortunate.” With ants, that manifests itself as the different functions each caste assumes. The implications of the discovery are huge, Abouheif added. It could shed light on the causes of certain diseases, like cancer. It could lead to fine-tuned agricultural practices or strategies for maintaining bio-diversity.
“It’s like with the doom and gloom of (talk about) global warming,” Abouheif said. “As soon as you’re changing the environment, you’re unleashing this potential everywhere.”