Ants have been trying to kill each other for 99 million years

Some of these ancient ants had a weapon modern ones don't: mammoth, tusk-like jaws that were probably used to impale prey. (Credit: Phillip Barden/Rutgers)

Like people, ants have long fought with each other and with other species over food and territory. But ants have been going at it for a lot longer than us—at least 99 million years.

“That’s a trait of ants,” says Phillip Barden, a fossil insect expert who works in the lab of Jessica Ware, assistant professor of biological sciences at Rutgers University. “Many ant species do that all the time. They’re always warring with either other individuals of the same species from different colonies or with different species.”

Fighting ants trapped in ancient Burmese amber from Myanmar suggest the ant wars began in the Cretaceous period, when dinosaurs still thrived.

“These early ants belong to lineages distinct from modern ants,” Barden says. “That is, they aren’t necessarily the direct ancestors of modern ants. They’re kind of their own branch doing their own thing.”

A new study, published in the journal Current Biology, provides strong evidence that ancient ants—like modern ones—were social, Barden says.

[Mesing with histone makes ants forage and scout]

“We have one piece of amber with as many as 21 worker ants trapped, and that’s significant because at this time period, ants are very rare to find in fossils. They make up less than 1 percent of all insects in amber. So to find 20 in one piece is highly suggestive of social behavior.”

Today, scientists have described 13,000 species of living ants and some researchers believe at least twice as many exist. Some may be related to ones that lived 99 million years ago.

Ants’ social behavior may be one reason why they’ve done so well over the years, Barden says. Instead of competing as one individual, they compete, in some cases, as tens of thousands, if not millions, and most aren’t reproducing. Instead, most work for a colony—a beneficial trait.

Some of these ancient ants also had a weapon modern ones don’t: mammoth, tusk-like jaws that were probably used to impale prey. Despite the social behavior and the fearsome jaws, the “hell ants” are extinct and no one knows why.

“It seems like they probably went extinct sometime in the 10 million years or so before or after dinosaurs went out,” Barden says. “It could have been climate. We also think it’s possible that the modern lineages actually out-competed these early ants.”

Source: Rutgers University