Tokyo, Japan - An ant colony rivalling the scale of human civilisation is right under our noses, according to Japanese and Spanish researchers.
Argentine ants (Linepithema humile) were originally native to South America, but have spread all over the globe.
They form huge colonies: in Europe, one vast colony is believed to stretch for 6,000km (3,700 miles) along the Mediterranean coast, while another in the US covers 900km (560 miles) along the coast of California. A third huge colony exists on the west coast of Japan.
Now, according to a team at the University of Tokyo, it seems that these groups are in fact part of a single, global colony.
Ants are known to attack members of different colonies based on their smell, while tolerating members of their own. When they come into contact, they recognise one other by the chemical composition of their cuticles.
The team selected wild ants from the main European super-colony, a smaller one on the Iberian coast, the Californian and Japanese super-colonies and another in Kobe, Japan. They then examined how aggressive the ants were to one another.
Ants from the smaller colonies were always aggressive to one another. But whenever ants from the three super-colonies met, they acted like long-lost friends, rubbing antennae together.
The researchers suggest that the colony spread around the world through human activity.
The findings are reported in Insect Sociaux.