Are devotees of the new Paleo diet right to think our prehistoric ancestors ate and lived better?

Modern food is bad for our health. The food industry is poisoning us. To save ourselves, we should eat like cavemen. That, at least, is according to gurus of the Paleo and gluten-free diets, the latest food fads from the West. Natural fruits, veggies, nuts and seeds are in. Some meat, poultry, fish and other seafood are OK, too. But processed food, sugar, salt, diary products and anything with gluten are bad.

This is based on the belief that our prehistoric ancestors - the hunters-gatherers - not only ate better, but lived better before the agricultural revolution, which turned them into farmers, free roaming into back-breaking farm work.

The hardcore Paleo crowds are also against eating cereals and grains, including wheat and legumes like beans and soybeans. At first I had no idea why. But it makes sense if you realise the domestication of grains and other plants defined the agricultural revolution, which gives most people the diets we still eat today. And it's precisely those food items the Paleo people reject.

Many Paleo-diet followers may not realise it but their gurus are actually following an intellectually respectable tradition that has called into question the agricultural revolution and its terrible effects on subsequent human developments. It all started after 10,000 BC and worked its way over the next millennium to replace hunters - whose diets some of us are now trying to imitate - with farmers who grew grains like rice and wheat and domesticated animals.

Where do we get the idea we should eat like cavemen? Or let me rephrase it, where do we get the idea prehistoric cavemen ate better than most of "civilised" humanity throughout history?

At the height of the 1968 student revolt in France, an American anthropologist called Marshall Sahlins published in Les Temps Modernes, the journal founded and edited by Jean-Paul Sartre and Simone de Beauvoir, one of the most influential papers in his field.

In it, he argues that hunters-gatherers before the arrival of agriculture had few needs and could easily satisfy themselves with what he calls "a marvelously varied diet". They had few possessions but they were not poor. Foragers, he argued, needed to work only 21 to 35 hours per week to get enough to eat and live. The rest was leisure time. This challenged the field's party line at the time that foragers lived on subsistence and often starved and it was the agricultural revolution that made the great leap forward to the land of plenty and civilisation.