Editor’s Note: Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Plants, algae, fungi, and animals — ...

Here’s what you’ll learn when you read this story: The first eukaryotes—the cells that form complex life—likely originated when two microscopic entities merged via a process called endosymbiosis, ...

Approximately four billion years ago, the first forms of life emerged on Earth. For eons, biological life consisted of prokaryotic organisms, either early bacteria or archaea. Determining when ...