By John Timmer, at ars technica:
Lancelet (amphioxus) genome and the origin of vertebrates
Those of you who took high school biology may remember the lancelet, also known as the amphioxus. Its simplified body plan is notable for containing a number of features that it shares in common with us vertebrates, such as a dorsal neural tube, presence of a notochord, segmented body muscles, and tail. That combination of simplicity and shared features has suggested to many that the amphioxus might shed light on the origin of the chordates. That suggestion has been dramatically confirmed by the completion of the genome of the Florida lancelet, Branchiostoma floridae, published today in Nature, with three accompanying publications that will appear later in Genome Research.
Over 500 million years ago a spineless creature on the ocean floor experienced two successive doublings in the amount of its DNA, a “mistake” that eventually triggered the evolution of humans and many other animals, says a new study: here.