The human body has traits that evolved at different times, from 1.5 billion to 2 million years ago, each bringing health benefits and risks. Multicellularity enabled organs and cancer. The immune system defends us but can cause inflammation. Breastfeeding supports infant health but relates to breast cancer risk. Menstruation and invasive placentas improved reproduction but led to pain and cancer risks. Human-specific traits like bipedalism and aging brought new issues like back pain and childbirth problems. Hair loss and sweat glands helped us stay cool but increased skin cancer risk. Our hunter-gatherer past shaped our microbiome and health, but also made us prone to modern diseases from lifestyle changes. (#40701)