#232During pregnancy the brain undergoes profound changes – almost every part of the cortex thins out and loses volume by the third trimester. It’s such a big change that you can tell if someone’s pregnant just by looking at a scan of their brain. How researchers discovered these changes and why they might be occurring.A massive, ancient group of cities has been discovered in the Amazon rainforest using lasers. It’s the biggest pre-Columbian urban area ever found in the Amazon and parts of it date back further than any other settlement too. So why have we only just found it and why was it abandoned?Where does stuff go when it’s sucked into a black hole? Based on Stephen Hawking’s theory that black holes slowly evaporate, most of it just disappears. But in physics, information about that matter can’t just disappear – so what’s going on? Many teams have tried to solve this paradox, but an intriguing new idea may bring us closer to an answer. Once we develop a whole range of groundbreaking new spacecraft technology, that is.Every single year, hammer corals change their sex, swapping between male and female. While many animals, including corals, change their sex across their lifetimes, this clockwork, routine schedule is quite unusual. But it turns out a habit of change might be useful to help ensure successful reproduction in the ocean. Plus: Making lithium-ion batteries with 70 per cent less lithium – with help from AI; staving off the amphibian apocalypse with fungus-resistant frogs; and the discovery of the oldest known fossil skin.Hosts Timothy Revell and Christie Taylor discuss with guests Alex Wilkins, Grace Wade, Michael Le Page and Sophie Bushwick. To read more about these stories, visit newscientist.com. Hosted on Acast. See acast.com/privacy for more information.