How to Grow a New Limb

Dr. Alejandro Sánchez Alvarado presents a talk on the biology of regeneration, focusing on how certain animals can regrow lost body parts. He introduces the topic by noting that biomedical research addresses three main questions: how bodies are made, how they are maintained, and how they replenish parts. He highlights that humans lose billions of cells daily and yet maintain stability. He then surveys the animal kingdom, showing that regeneration is widespread, from sea anemones to salamanders and even mammals like deer that regrow antlers. He emphasizes that many animals, including planarians, can regenerate entire bodies from fragments. He argues that current biomedical research focuses on a limited set of model organisms, missing the vast diversity of life that could reveal new mechanisms. He uses the Pythagorean theorem as an analogy to encourage thinking about complex problems in new ways. He introduces his model organism, the planarian Schmidtea mediterranea, and explains its advantages for studying regeneration. He shows how planarians reproduce asexually by splitting and regenerating, and discusses their ability to shrink under starvation. He concludes by suggesting that studying diverse organisms can lead to discoveries relevant to human health.