We see evidence of harvesting of bone marrow in faunal assembles where you see characteristic cutting open of the bones, like you see here, for marrow extraction. Now sure, people did eat meat, and especially in the Arctic and areas with long periods where plants were not available, they would have eaten a lot of meat. But people that lived in more temperate or tropical regions would have had a very large plant portion of their diet.
So where does this Meat Myth come from? There’s really two places, and one is the inherent bias in the archaeological record. Bone is 80% mineral by weight, it’s going to preserve better and longer over thousands of years than delicate plant remains.
But the other issue comes from some early bone biochemistry studies that were performed on Neanderthals and early people. This bone biochemistry study is based on something called nitrogen stable isotope analysis. It’s complicated, but I’m going to try and break it down.
The basic idea is that you are what you eat, and so we – there’s nitrogen-15 and nitrogen-14, heavy and light versions of nitrogen – and we consume this nitrogen in our food. But there’s one important difference, and that is, with each step that you go up the trophic hierarchy, the amount of the heavier isotope increases.
So if you measure the amount of heavy isotope in the bone, you can infer where that individual was on a food chain. This is an example of a generalized isotopic model. I’ve plotted where plants generally fall, and above them are the herbivores, and then above them, the carnivores.
But one of the problems is that not all ecosystems conform to this model. There’s a lot of regional variability, so if you don’t understand the region, you can come to erroneous conclusions. I’ll give you some examples.
We can take East Africa. If we measure animals and ancient humans in East Africa, we see some very strange patterns. First of all, how can a human be higher than a lion? Lions only eat other animals. And then, how is this herbivore above a lion? Well, it turns out that the food that you eat is not the only contributor to these isotopic values and that aridity can also have an impact.
So what we’re likely seeing here is differences in water access. So let’s move out of the savannah and move into the tropical areas. Let’s look at the ancient Maya. Again, we see something anomalous. We see the ancient Maya lining up with jaguars. Now, we know the ancient Maya had a diet heavily reliant on corn.
So what’s happening here? We don’t exactly know, but we think this may have to do with the way they performed agriculture and how they fertilized their crops.
Now let’s go to the Pleistocene. We see some really interesting patterns here too. We see reindeer plotting very low, in the range of plants. We see wolves plotting normally where you would see herbivores, and we see mammoths spanning all three levels, at once plants, herbivores and carnivores.
So what we think is happening here is that in very cold climates, animals eat unusual things and in this case what we think is happening is these mammoths are eating lichens and bark and that’s giving them very strange values. So if we now go to humans, ancient humans, Palaeolithic humans, and Neanderthals, we see that they plot in the same isotopic space as wolves and hyenas.
Now that’s true, but as I’ve shown, if you don’t have good control over the regional isotopic ecology, you can come to an erroneous conclusion, and I think it’s premature to say this is very strong evidence of meat consumption, given how very little we really know about the Palaeolithic ecosystems.
Myth #2: Palaeolithic peoples did not eat whole grains or legumes
So, myth two is that Palaeolithic peoples did not eat whole grains or legumes. Now, we have stone tool evidence from at least 30,000 years ago – that’s 20,000 years before the invention of agriculture – of people using stone tools that look like mortars and pestles to grind up seeds and grain.
More recently we’ve been developing techniques where we can actually measure this thing called “dental calculus.” It’s very interesting: it’s fossilized dental plaque. We can go in the individual mouths of people, pull out that plaque and recover microfossils of plants and other remains. My team is working on developing methods to extract DNA and proteins, and other research groups are focusing on these microfossils like starch grains, pollen and phytoliths.
Now, we’re still in early days here, but even with the limited research we have, we can say that there is an abundance of plant remains inside the dental calculus of Paleolithic peoples. And these things include grains, including barley. We’re finding barley inside Neanderthal teeth, or inside the plaque. We also have legumes and tubers.
Myth #3: Paleo Diet foods were eaten by Palaeolithic ancestors
So, myth three is that Paleo Diet foods, in the fad diet, are what our Palaeolithic ancestors ate. That’s just not true.
Every single food that’s pictured in these advertisements are all domesticated foods, products of farming, of agriculture. They’re from the Neolithic transition.
Let’s give an example – bananas. Bananas are the ultimate farmer’s food. They can’t reproduce in the wild anymore. We’ve bred out their ability to make seeds. So every banana you’ve ever eaten is a genetic clone of every other banana, grown from cuttings. They’re definitely a farmer’s food. If you were to eat a wild banana, it is so full of seeds that I bet many people in this room wouldn’t even recognize it as edible.
Let’s take salads, that seems like a really great Paleo Diet food. Except that we’ve radically changed the ingredients to suit our needs. So, wild lettuces contain a great deal of latex, which is indigestible and irritates our gastrointestinal system. It’s bitter, the leaves are tough. We’ve domesticated them to be softer, to produce bigger leaves, to remove the latex and the bitterness, remove the spines that grow on the leaves and stems of wild varieties, make them tastier for us.
The tomato that’s shown here lacks the tomatine and solanine toxins that are present in its wild relatives, which are all members of the poisonous nightshade family. If we look at oil, it’s true that olive oil is the only natural vegetable oil that can be harvested without synthetic chemicals. Except, it still requires at least rudimentary presses to remove it, something that no Palaeolithic person would have ever built. This is a farmer’s food.