Far from extinct, the caveman is making a comeback.
In a behemoth manner.
Paleo was the most searched diet term on Google in 2013, caveman cafes are cropping up in capital cities around the country and if you look for paleo books on Amazon you will get close to 4000 listings. There were nearly 20 new books published on the topic in the past month alone.
Since the original book promoting paleo, The Paleo Diet by Dr Loren Cordain, was published in 2001, it has certainly been catapulted into public consciousness.
But the diet remains one of the most divisive out there.
Paleo advocates eating how our ancestors theoretically ate 10,000 years ago, pre-agriculture and thus before grains, dairy, sugar, pulses and processed foods were introduced en masse.
The idea, for those who have been living in a cave, is that our genes have not had time to adapt to the rapid (from an evolutionary perspective) changes to our diet. The Western diet as we know it has, paleo-proponants say, led to many of the health issues we face today.
So, paleos are encouraged to emulate the hunter-gatherer lifestyle of old and and stick to grass-fed meat, vegetables, some fruit, nuts and seeds. Ideally, all organic.
Seems simple and healthy enough. Yet paleo was rated the worst of the 29 diets in US News and World report's most recent best and worst diets survey.
The panel of expert judges took issue with every aspect of the regime, saying it was too restrictive, too hard to follow, ineffective for weight loss and unhelpful for heart health.
Its wooden spoon status is incomprehensible to many, including Scott Gooding, personal trainer and co-author of the paleo-inspired lifestyle book Clean Living.
"I find that astonishing," he says. "I'm a massive advocate of paleo. I think it's one of those diets that's easy to adhere to – it's a really clean diet, you're not eating anything processed, anything refined or anything synthetic.
"So if anyone's conscious of their health and of optimal health it's definitely a diet that should be investigated."
But a recent article by Scientific American also took aim at paleo, painting the diet as "half-baked". Apart from saying that the image of the caveman as a "tall, lean, ripped and agile 30-year-old" is idealistic at best, paleo is pulled apart for its sketchy science.
"If humans and other organisms could only thrive in circumstances similar to the ones their predecessors lived in, life would not have lasted very long," it says. The feature also points out that the details around the Paleolithic diet "remain murky" and humans may have been eating grains and dairy for longer than initially thought.
Certainly Chris Kesser, in his new book Your Personal Paleo Code, concedes that we are not carbon copies of cavemen. Dairy, for instance, need not be entirely eliminated if you are lactose tolerant. "It seems clear now that there are some genetic changes that allow some of us to partially adapt to agriculture," Kesser says.
Gooding agrees that a paleo approach doesn't necessarily mean perfect adherence. For non-purists it can simply help steer them away from processed foods.
"It's about replicating it as best we can," says Gooding, who personally eats organically and avoids all grains, sugar, pulses and dairy.
"You don't have to go as extreme as someone like me. Everyone is on a spectrum – it's all about improving and being a better version of yourself.
"By being aware that there are choices other than grains, other than dairy and trying to eliminate sugar you should make improvements in your health."
A new book takes the paleo health message a step further.
In his book Grain Brain: The Surprising Truth About Wheat, Carbs and Sugar – Your Brain's Silent Killers, David Perlmutter, a neurologist and fellow of the American College of Nutrition, reiterates the idea that grains are poisonous to humans.
Although dietitians the world over continue to defend wholegrains and gluten, unless you have coeliac disease, Perlmutter says that gluten (and sugar) spike blood sugars, causing inflammation to the brain. This inflammation, he tells The Sunday Times, "sets the stage for a brain that falls apart".
Adopting a paleo-style diet (Perlmutter's version includes some dairy and gluten-free grains such as quinoa and rice) can "save" your brain from conditions including dementia and Alzheimer's disease, he says.
He also defends criticisms that the restrictions of paleo result in a nutrient-depleted diet.
"The idea that people are nutritionally deprived because they don't eat grain has no scientific basis," he tells US Health News.
His book has received criticism from those concerned about people taking an unecessarily extreme approach to their diet.
But Perlmutter is unrepentant.
"Halfway measures work halfway," he says. "Even small amounts of cheating can have large inflammation results."
Author and dietitian with a PhD in nutritional science Dr Joanna McMillan agrees with taking an anti-inflammatory approach, "but such a diet does not need to cut out grains", she says.
"First of all, much of this is based on his hypotheses, not scientific evidence. Some of it is based in science but has then been exaggerated.
"So for example we certainly know that if your blood glucose levels regularly run too high, even if you are not a diabetic, this is bad for the brain (as well as other organs). However, you don't need to cut out all grains and sugar to control blood glucose levels."
McMillan also takes issue with Perlmutter's argument that we are not wired to eat grains.
"We have done so for some 10,000 years and so I would argue that it is much more important to consider what have we done to grains in the last 50-100 years that may be causing us problems.
"The answer is we have refined them, thrown out much of the good stuff (the fibre and nutrients) and processed them into energy dense, easy-to-over-consume food products.
"It is not carbohydrate or grains per se that are our problem, but too many cakes, biscuits, refined breads, bagels, pikelets, lollies, confectionary and so on. Team that with insufficient whole plant foods and a sedentary lifestyle and you have a recipe for disaster."
Whether you bin the bread altogether or just cut down on the cakes, the cavemen are at the very least getting us thinking and talking about the modern-day diet.
"We can all make advances in our lifestyle, we can all make improvements in our health," Gooding says. "It's just being open to another way of life . . . but you can't put a price on your health."