Credit: Curr. Biol.

The separate castes of social insects — queens, workers and soldiers — first appeared in termites at least 100 million years ago, according to newly discovered fossils.

Although evolutionary studies have suggested that termites were first to evolve castes, there was very little fossil evidence for this. Now, Michael Engel at the University of Kansas in Lawrence, David Grimaldi at the American Museum of Natural History in New York and their colleagues report the discovery of six termite species fossilized in amber from Myanmar, which show evidence of distinct castes.

The 100-million-year-old fossils include two new species, which the authors call Krishnatermes yoddha, with queens, workers and soldiers (pictured), and Gigantotermes rex, whose 2-centimetre-long soldiers are among the largest ever reported.

Curr. Biol. (2016)