Today’s extinction rates are sky-high. But scientists debate if that’s sufficient evidence to conclude that Earth is undergoing a mass extinction event—or whether that’s even a helpful designation.
The genomes of living animals are littered with DNA from long-gone relatives, providing a lens on evolution, past extinctions, and perhaps even solutions to agricultural problems.
In the 20th century, animals such as mules and ligers that had parents of different species were considered biological flukes, but genetic sequencing is beginning to unravel the critical role of hybridization in evolution.
An isotopic analysis of eggshell beads dating back more than 30,000 years indicates that they helped build networks that stretched for hundreds of kilometers.