Evolution's toolkit seen in developing hands and arms

Thousands of sequences that control genes are active in the developing human limb and may have driven the evolution of the human hand and foot, a comparative genomics study led by Yale School of Medicine researchers has found.

Video: The mystery of spiral galaxies and their enigmatic arms

Our very own Milky Way is likely a spiral galaxy. Indeed, our solar system and Earth reside somewhere near one of its filamentous, swept-back arms.