Insects Evolved: the When and the Why

Insects are wildly diverse and important for life on Earth. Most of our major crop plants are pollinated by insects, and yet we have barely scratched the surface when it comes to everything we know about insects, from their physiology and ecology to their evolution. This week, Misof et al., (Misof et al. 2014, Science 346:763-767) looked at the genetics of 103 insect species to construct the evolutionary history of insects and the ancestral relationships between insect species that exist today. Based on their results, insects likely evolved about 479 million years ago in aquatic environments, and spread to terrestrial environment when plants colonized land.

But why are insects so diverse? Misof et al. found that insects diversified around the same time that other scientists estimate the origin of insect flight over 300 million years ago. As well, many groups pollinating insects such as bees, wasps, flies, and butterflies rapidly diversified at the same time as flowering plants, showing how intricately link insect and plant diversity are, and how important insects may have been in the evolution of our major food sources. All of the findings of Misof et al. can be summarized in a beautiful figure showing the evolutionary relationships between groups of insects, the timing of their evolution, and the coincidence of other major biological and geological events. A key note is that major diversification events in the evolution of insects coincide with diversification events in the evolution of plants.

And as for those creepy crawling bugs or buzzing flies that might annoy or scare you, they were an essential component in the evolution of life on Earth, and you have them to thank, whether directly or indirectly, for being able to eat. So the next time you see an insect and are thinking of squashing it, unless it is a threat to someone’s health, remember how much you owe to its ancestors and let it live.

Stay safe and stay informed,
Joe