Four hundred million years ago, some fish hoisted themselves out of the water and started a long evolutionary trek to personhood. But how did they learn to walk? A study published in this week’s Nature uses modern-day walking fish to mimic that transition.In the experiment, researchers raised bichirs, which are fish with functional lungs and strong fins. In a pinch, these qualities allow them to walk on land. But this is something new: For eight months, a group of the primitive fish were raised entirely on land so that researchers could compare their development to specimens that grew up in normal, mostly aquatic conditions."I was most surprised early in the study when the Polypros [bichir] actually survived in the terrestrial habitat. That was amazing," said Emily Standen, the lead author and an evolutionary biomechanist at the University of Ottawa. "Then when we tested their behavioral and anatomical differences, we were really excited."