The evolution of the amniotic egg -- complete with membrane and shell -- was key to vertebrates leaving the oceans and colonizing the land and air but how bird eggs evolved into so many different shapes and sizes has long been a mystery. Now, an international team of scientists took a quantitative approach to that question and found that adaptations for flight may have been critical drivers of egg-shape variation in birds.
A unique repair mechanism has been discovered in the developing backbone of zebrafish that could give insight into why spinal discs of longer-lived organisms like humans degenerate with age. The repair mechanism protects fluid-filled cells of the notochord, the precursor of the spine, from mechanical stress. Notochord cells eventually form the gelatinous center of intervertebral discs, the structures that often degenerate with age to cause back and neck pain.
There were warning signs that populations of commercially harvested whales were heading for global collapse up to 40 years before the event, a study of historic whaling records has revealed.