Plot: 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