What did you have for your Christmas dinner? The traditional turkey? A vegetarian meal? And how did the turkey tradition start? What did people have for Christmas dinner 500 years ago? Just how is your Christmas meal turned into you? John takes us on a journey through time from our earliest ancestors, on the way exploring how scientists have come to understand the diets of our fossil ancestors from studying their teeth and bones and how differences in food habits among populations and cultures have arisen. We ask whether our diets today are a result of evolutionary adaptations or chance, and how origins of agriculture 10,000 years ago transformed the food habits of our ancestors as we moved from hunting and gathering to growing crops and keeping livestock. We humans are unique in the animal kingdom because we cook much of our food before we eat it. What has been the impact of cooking both on the range of foods we can eat and on our evolution? In this lecture we learn about genetic differences among populations in ability to deal with certain foods and come to understand why some like it hot, spicing up their food with chillies and other hot spices.