From pollinating our flowers to spreading deadly diseases, insects are everywhere.

Scientists have been trying to get a better understanding of their history for a long time. A research team unveiled on Thursday what it has called the most comprehensive insect family tree ever created.

Using genetic data tot race insect origins back nearly half a billion years ago, the researchers were able to clarify the relationships among the major insect groups, according to Reuters.

Scientists analyzed 1,478 genes from 144 species covering all of the major insect groups to resolve longstanding questions about the evolution and diversification of Earth's most diverse and largest animal group.

"Two-thirds of all known animal species are insects," said Bernhard Misof of the Zoological Research Museum Alexander Koenig in Germany, one of the leaders of the study published in the journal Science. "They are the important players in terrestrial ecosystems, together with plants."

The first insects appeared 480 million years ago at around the same time as the first land plants, the scientists estimated based on the genetic data, according to Reuters.

That date is 70 million years earlier than the oldest-known insect fossil.

"The Earth 480 million years ago looked more like Mars than our Earth today: nothing but rock, with no life on land. The oceans were full of life, but life out of the water is really quite challenging," said evolutionary biologist Karl Kjer of Rutgers University in New Jersey, another of the study leaders.

"Plants and insects co-evolved simultaneously, each shaping the other," Kjer added.

Misof said there is a prerequisite for insects evolving on land. They must have been the presence of organic food in the form of the first modest terrestrial plants. The first insects likely evolved from a group of venomous crustaceans called remipedia, the scientists said this week.

"We have absolutely no clue of how the first terrestrial insects might have looked, but somehow they must have resembled an animal with crustacean and insect features," Misof added.

The scientists said the first winged insects likely appeared about 400 million years ago as land plants began to grow skyward to create forests, according to Reuters. It would be about 200 million years before any other type of animal obtained the ability to fly.

The oldest-known insect wing fossil is approximately 340 million years old.

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