In a bid to unravel how insects have evolved, over 100 researchers from many parts of the world have collaborated on the 1KITE (1K Insect Transcriptome Evolution) project to come up with what is now considered the most comprehensive family tree of insects.

Insects, the world's most diverse animal group, may be small but they play a crucial role in this planet as they aid in the pollination of plants and serve as food. These little creatures can also pose problems such as when they transmit potentially fatal diseases. The research has shed light on things such as when the ability to fly, parasitism and herbivory have evolved.

"We have not had a very clear picture of how insects evolved--from the origins of metamorphosis to which insects were first to fly," said study researcher Michelle Trautwein, from the California Academy of Sciences. "New sequencing technology allowed us to compare huge amounts of genetic data, and for the first time ever, we can fill these knowledge gaps. Science is taking us closer to solving the mysteries of the evolution of life than ever before."

The international research team analyzed 1,478 genes from 144 insect species that cover all of the major insect groups to trace the origins of insects and clear up their diversification. They found that insects, along with plants, have shaped the earliest terrestrial ecosystem and developed their wings that gave them the ability to fly about 400 million years ago, earlier than any other animal could fly and almost the same time when plants that thrived on land initially grew skywards to form forests.

"We dated the origin of insects to the Early Ordovician [~479 million years ago (Ma)], of insect flight to the Early Devonian (~406 Ma), of major extant lineages to the Mississippian (~345 Ma), and the major diversification of holometabolous insects to the Early Cretaceous," the researchers wrote in their study, which was published in the journal Science on Nov. 7.

Study author Bernhard Misof, from the Zoological Research Museum Alexander Koenig in Germany, said that as the insects evolved on land, they must have need organic food that came in the form of the early and modest terrestrial plants. Insects, which currently make up two-thirds of all known species of animals on Earth, also likely evolved from a group of poisonous crustaceans known as remipedia.

Misof said that while they do not have clues on how the first land insects might have looked like, it is possible that they looked like creatures that had crustacean and insect features.