The emergence of flowering plants 100 million years ago may have led to the explosion in ant diversity that occurred around the same time, scientists say.
The 11,800 known species of modern ants probably arose from a single species millions of years ago, but scientists previously knew little about ants' evolutionary history.
Researchers analyzed fossilized ants trapped in amber and discovered that the ancestors of modern ants first scurried along the ground 140 to 168 million years ago.
These ants, however, were diversifying at a very slow rate. Then flowers, also known as angiosperms, sprouted onto the scene.
"An event happened 100 million years ago and ants started diversifying like crazy," study co-author Corrie Moreau of Harvard University told LiveScience. "This is also the time when we start seeing the first angiosperm forests."
These forests dropped more litter to the ground, creating more niches and complicated habitats for ants to specialize and diversify in. Today the greatest ant diversity is observed in plant debris and just under the soil. Forest canopies also provided interesting new homes for ants, including some that have learned to glide back to their home tree if the fall.
Other insects experienced a boom with the coming of flowers. These insects also lived among the debris, creating a massive new food source for ants. The flowering plants would make pretty good ant snacks themselves.
Today, ants account for an estimated 15 to 20 percent of the world's animal biomass. As scavengers, they keep the ground neat by munching on dead debris, and some scientists believe they turn over more soil than earthworms.
The study is detailed in the April 7 issue of the journal Science.