Growing Up and Growing Old - Lecture 6

Explore the fascinating science of growth, hormones, and aging in this concluding lecture from Professor Lewis Wolpert's 1986 Christmas Lectures series on developmental biology. Delve into the mechanisms of regeneration, examining how hydra can regrow heads without growth while newts require growth to regenerate limbs, and discover how a polar coordinate system model explains why cockroach legs develop extra limbs when rotated 180 degrees. Learn how growth is programmed from the earliest stages of development, with arms measuring just millimeters eventually growing to identical lengths after 18 years despite developing independently. Understand the crucial role of hormones in controlling overall growth, from how growth hormone deficiency creates dwarfism to how excess produces gigantism, and explore how sexual differences arise from male hormones acting on essentially female tissue templates triggered by the Y chromosome. Investigate how timing variations in growth can dramatically alter animal forms, potentially explaining features like the giant antlers of the Irish Elk through extended growth periods. Examine aging through the lens of wear-and-tear theory and developmental programming limitations, including the discovery that normal skin cells can only divide a finite number of times in culture. Consider the paradox of increased longevity without extended lifespan over the past century, and contemplate fundamental questions about species-specific aging rates and the possibility of extending human life, all while connecting these concepts to Mary Shelley's Frankenstein and the quest to understand life's generation.