Millions of years ago, retroviruses infected our ancestors and left their genes in our DNA; these remnants make up about 8% of the human genome. One of them was repurposed. Syncytin, a protein the virus once used to fuse with cells, now helps build the layer of the placenta that interfaces with the mother's blood.
In 2022, a young tagged bar-tailed godwit flew from Alaska to Tasmania in about 11 days of nonstop flight, covering 13,560 km without eating, drinking or landing. Before departure, these birds pile on huge fat reserves and shrink their digestive organs, which are useless during the journey.
To escape rivals, a dung beetle rolls its ball of dung in a straight line. At night, it holds its course using the glowing band of the Milky Way. In a planetarium, researchers showed that beetles rolled straight under a starry sky but wandered aimlessly when the galaxy was switched off. It was the first animal known to navigate this way.