For decades, scientists have believed that complex life began when two very different microbes joined forces, eventually ...

The most widely accepted scientific explanation for the arrival of all complex life on Earth has had an unsolved mystery at its heart. According to the theory, all plants, animals and fungi, known ...

Living cells are highly organized, yet they are not assembled using rigid blueprints or by following a predetermined plan.

In the oceans and on land, scientists are discovering rare, transitional organisms that bridge the gap between Earth’s simplest cells and today’s complex ones.

Scientists propose that eukaryotes formed when an Asgard archaeon entered into a close partnership with an alphaproteobacterium. Over time, the two organisms became permanently linked. The ...