Thor, the legendary Norse god from the mythological city of Asgard, is not alone. According to groundbreaking research published in the journal Nature, we humans—along with eagles, starfish, daisies and every complex organism on Earth—are, in a sense, Asgardians.
I’m not sure about this particular paper, but usually you can compare the number of mutations in a common protein and use that to estimate how long ago a common ancestor existed. As an example here is a graph of the number of mutations in mitochondrial DNA for the protein Cytochrome C. The more mutations you accumulate in a genome the larger amount of time since they split from a common ancestor.