An amphioxus (also called a lancelet), which is a very distant cousin to humans and other vertebrates. It is the creature most similar to the original spineless organism that existed before a major genomic event occurred. | Carol MacKintosh

500-Million-Year-Old 'Mistake' Led to Humans

A spineless creature experienced two doublings in DNA, triggering the evolution of humans and other animals.

July 24, 2012
3:00 AM EDT