ach dolphin makes its own unique whistle, and close friends or family will reply with the same sound. The findings, published today (July 22) in the journal Proceedings of the National Academy of Sciences, suggest the dolphins use the whistles like names. Past research showed individual dolphins had personal whistles, but it wasn't clear that other members of their group learned that whistle.
Scientists in China say they have successfully grown a human tooth using stem cells taken from urine.
Researchers say the technique could one day be used as a way to replace teeth lost through aging and poor dental hygiene, with the added bonus that urine is deemed a less controversial source of stem cells than human embryos.
Although they look far apart, M31 and M33 are locked in a mutual gravitational embrace. Radio astronomers have found indications of a bridge of neutral hydrogen gas that could connect the two, evidence of a closer encounter in the past. Based on measurements, gravitational simulations currently predict that the Milky Way, M31, and M33 will all undergo mutual close encounters and potentially mergers, billions of years in the future.