I watch Rufus, a friend’s dog, chew enthusiastically on a rubber bone. I know the dog is alive, and his toy is not. I know that intuitively. But can I prove it scientifically? Can science parse the ...

It's tiny and needy, but is it alive? That's a question prompted by recent research that highlights a surprisingly complex part of biology. The organism in question is a microbe called Sukunaarchaeum ...