Stable isotope analysis has startled the archaeological community by showing a rapid and widespread change from a marine to terrestrial diet (ie from fish to domesticated plants and animals) as people moved from a Mesolithic to a Neolithic culture. This could be a consequence of domestication, or as Julian Thomas (2003) proposed, of a kind of taboo (‘Touch not the fish’). In a key challenge, Nicky Milner and her colleagues (2004) questioned the reality of this nutritional revolution, contrasting the message of the bones and shells found on settlement sites, with the isotope measurements in the bones of people. Here Mike Richards and Rick Schulting, champions of the diet-revolution, strongly reinforce the arguments. The change was real, it seems: so what does it mean? Milner and colleagues respond.