Dolphins and whales experience pleasure
Sam Ridgway has spent most of his life learning about dolphins and whales. Over his five-decade career he has asked these cetaceans various questions, including how deep they can dive and how depth affects their hearing. As he trained each animal to answer his questions, he rewarded them with tasty fish treats, and each time that they received a reward he remembers that they squealed. Initially he thought that the squeals were food signals, where animals communicate the presence of food to nearby members of their species. It was only when his wife Jeanette suggested that the squeals reminded her of delighted children that he began to ponder whether there was more to the cetaceans' cries: could they be genuine expressions of delight? Ridgway publishes his discovered that the time delay between dolphins and whales receiving a reward and their squeals is the same as the delay between a pleasant...