Is evolution like a well-tuned car that purrs down the road at a steady pace? Or is it more like an aging, rattling jalopy that often lurches forward? The aging jalopy is a handy metaphor for the ...

The concept of punctuated equilibrium was, to some, a radical new idea when it was first proposed by Stephen Jay Gould and Niles Eldredge in 1972. Now it is widely recognized as a useful model for one ...