What did our ancestors eat? - Part 1

Have you ever wondered what did our ancestors ate? At least I have many times, but the truth is not 100% clear. Some studies say a lot of meat, other say a lot of vegetables and that we were almost vegetarian, other say it doesn’t matter because they died young.

My years as a researcher taught me that what's in the literature and the reality are different things. A scientific article at the end is written by a human being that can have biases and even if the data says something, everything can be misinterpreted or twisted. Then journalist come and twist the findings even more. And lastly regular people without a science degree read what the journalists say, and they understand what they want or can.

Besides my years as a researcher, I've tried several diets like vegan, vegetarian, and carnivore which have taught me that what a study says and how I feel in a given diet are not the same thing at all.

I'll split this post into two parts, in the first part we are going to see what our ancestors ate in the Paleolithic and in the second part the Neolithic until the beginning of the common era. To write this post I read several articles about what homos eat thousands of years ago. As I expected I found conflicting information, so I figured I should summarize what I found and give you a pre-digested version and give you my opinion as well.

Homo evolution

I'm not an expert on this matter, so excuse me if I say something wrong, but I'll try to roughly explain human evolution. Monkeys and humans have a common ancestor. At some point in the evolution, some primates stayed behind and are what we know as chimpanzees, orangutans etc. Other primates evolved to homos. The only homos that survived until this day are the homo sapiens sapiens or humans, although some humans have a 20% of Neanderthal.

Going from primates to humans, our bodies suffered a few changes:

• We learnt to walk straight.
• The jaw became smaller
• The brain got bigger
• The intestines became smaller
• The metabolism changed making it more inefficient to digest plants.

As you can see from the image, monkeys have bigger jaws than us and the part of the skull where is the brain is larger in humans. There are two theories for these changes, one says it's because of the meat consumption and the other say it's because of the nutrient rich fruits and vegetables consumption.

In my humble opinion the meat theory is stronger, and it's based in the following principles (1):

• The bigger monkey jaws are needed to break leaves and branches easily. Meat consumption doesn't need those big jaws because meat is softer not as rough as branches.
• Our brains got bigger because we learnt more things and got smarter (how to make fire, etc.), a bigger brain requires more nutrients and meat is better than plants in that aspect.
• Herbivores need a powerful digestive system to get real benefits from plants. Humans have smaller intestines than monkeys, we cannot get the same benefits from plants as them.
• A proper brain development needs docosahexaenoic acid (an omega-3) and arachidonic acid (an omega-6), these both essential amino acids are found in large quantities in bone marrow (there are evidences of tools used to remove bone marrow from bones dated 2.5 millions of years ago (2)) and in ruminant brains.

The fruits and vegetables theory is based on the following (1):

• Humans are primates and all of them are herbivores.
• Jaws got smaller because the plants we ate were more nutritious than the ones the rest of the primates ate.
• Agriculture made us smarter and that’s why our brains god suddenly bigger.

The evidence to support the fruits and vegetables theory is not strong and the first statement is not true at all. Chimpanzees can eat up to 65 grams of meat during the dry season when plants are scarce (3).

Regarding the metabolism here you have a few reasons why humans are not herbivores:

• For a proper cellular function, humans need fatty acids of 20 and 22 carbons. As well as other carnivores, humans are inefficient at transforming fatty acids of 18 carbons from plants into the ones with 20 and 22 carbons.
• Humans can produce taurine (a non-essential amino acid) but we are not good at it, we need to eat meat to have optimal levels. Vegetarians and vegans tend to have lower taurine levels (4).

I've talked enough about theories and physical and metabolic changes across evolution. Now, let's see the evidence of what we eat.

Evidence of what we ate

There are several evidences: leftovers, feces, and isotopic analysis of δ13C and δ15N.

Leftovers

Most of the leftovers are animal bones because they preserve better. The oldest evidence of this are bones from Ethiopia from approximately 2,6 million years ago (5). Other well-preserved bones from 500 thousand years ago found at the south of England show cuts made with sharp tools used to rip off the meat.

By the way, part of the carnivore menu were the own homos (6, 7). There are a few evidences of cannibalism, although some believe it was for religious reasons.

Regarding the plants we ate, there are little evidences because most of the organic matter deteriorates easily. Here you have a list of the plants they ate:

• Different grains at least 30 thousand year ago (8, 9)
• Wild herbs 23 thousand year ago (9)
• Dates more than 40 thousand year ago (10)
• Legumes more than 40 thousand year ago (10)
• Seeds more than 40 thousand year ago (10, 11)
• Nuts 780 thousand year ago (11)
• Fruits 780 thousand year ago (11)
• Vegetables 780 thousand year ago (11)

Feces

Fossilized feces are also analyzed to know what our ancestors ate. In Alicante, Spain they found Neanderthal stools from 60700 to 54400 years ago (12). These feces tell us that Neanderthal at that time ate meat as well as plants.

Isotopic analysis

I personally believe that this kind of evidences are more reliable since an isotopic analysis is unequivocal. As far as I know the most reliable ones are tested on bone collagen. So, I'll not review the ones tested on bioapatite.

The analyzed isotopes are carbon 13 and nitrogen 15. Carbon tells us the source of the proteins an organism had for the last 10 years of life, and this gives us an idea of what types of plant ate the animals they ate, what types of plants they ate and if they ate or not sea products. Nitrogen 15 tells us how carnivore was an animal in their last 10 years of life, the higher the nitrogen 15 level, the higher in the trophic chain is an animal. What nitrogen 15 measures is the nitrogen present in the proteins in a food, when an herbivore eats plant, it accumulates nitrogen from that plant in itself, when a carnivore eats that herbivore it accumulates even more nitrogen in itself.

There are a few isotopic analyses that situate Neanderthal as carnivores, in fact sometimes highly carnivore (13, 14). So, they either ate a lot of meat or ate other carnivores. In some cases, depending on the location, these Neanderthals could get 50% of their proteins from fish and shellfish (14). These findings are from about 180000 to 40000 years ago.

In a review about the Neanderthals feeding habits (15), they concluded that Neanderthals were highly carnivore. In the next image you can see the chart where nitrogen 15 is in the Y axis and carbon 14 is in the X axis. As you can see comparing Neanderthals to other animals, they are similar to the carnivore’s ones like hyenas or wolves and not herbivores like a reindeer.

There are also isotopic analyses in humans. In another review they conclude that humans from 30000 to 10000 years ago were highly carnivore as well (16).

This doesn't mean that we all were carnivores, because these findings from Neanderthals and humans are from European remains (except for one found in China (15)). Unfortunately, there are no isotopic analyses of bone collagen in other parts of the world like the tropics where they probably ate more plants and starches (or at least I could not find them). Neither there are isotopic analyses in older homos like the Australopithecus (I found one, but it was bioapatite and I don't trust them).

Another reason to think that we were super carnivores is that as some of you might know, plant foods have less proteins than meat. Even if our ancestors ate plenty of vegetables, you wouldn’t see it reflected in the nitrogen 15 analyses because since they ate a lot of meat, their nitrogen 15 levels are high whether or not they ate plants.

Raw or cooked?

Once they learnt how to make fire, if they could make it then they probably cooked their food. There is evidence from 300000 years ago that tell us that they did cooked it (17). In the article “The Raw and the Stolen: Cooking and the Ecology of Human Origins” (18) they talk a lot about the role that cooking played in our evolution. I must say though, the authors believe in the fruits and vegetables theory.

They were lactose intolerant

Although they eat meat, they most likely didn’t drink milk. A genetic study of Scandinavian remains from the Neolithic showed that 95% of prehistorical individuals were lactose intolerant (19). I guess the genetic mutation (which is dominant, by the way) of lactose tolerance spread out more when humans became sedentary and domesticated their own animals. To this date only a 25% of Swedish are lactose intolerant, so the intolerance rate has changed a lot in 6000 years.

We will never know what they exactly ate

It is important to make clear that we will never be completely sure about what they eat through the year for various reasons:

• Although you can know how old the remains are, we don't know if it was summer or winter when they died, and diets change depending on the seasons.
• The available foods also depend on the location of the findings. What people ate along the tropics is not the same they ate near the poles.
• Animals and plants of that time weren’t like the ones we eat now. Animals had less fat and fruits and vegetables were tougher and less sweet.
• Knowing if they ate meat is easier thanks to the bones, knowing if they ate vegetables is more complicated for the degradation of the organic matter.

I remark this because now and then goes out a new article in the media saying bombastic thing of what our ancestors ate that are misleading.

Journalist twist scientific findings

About three years ago there was a study about the Neanderthal’s diet in the Paleolithic in Israel (12). The conclusions said that it wasn't true that during the Paleolithic they ate only meat, they found plenty of plants, seeds and nuts in an archaeological excavation. From this article some magazines had headlines like “Ancient leftovers show the real Paleo diet was a veggie feast)"

Do you think it’s ok to say that our ancestors were feasting on vegetables based on some remains found in one specific part of the world? That would be like if an alien captured a vegetarian human and concluded that all humans are vegetarian, ridiculous. That’s why I think that the information that gets to ordinary people is not to be trusted.

If we look at the extended conclusions of the original study, it says the following:

“The food plant remains were part of a much more diverse diet that probably included additional food plant species, fish, amphibians, reptiles, birds, mammals, such as fallow deer, elephants, and various aquatic and terrestrial invertebrates.”

But the person who wrote the article in the magazine New Scientist the scientific article said that the paleolithic diet was a vegetarian feast. What we read in the press is not to be trusted.

I think the logic conclusion is that our ancestors had the same thing in their mind as we do: eat and have sex. Keeping this is mind and knowing that at that time there weren’t millennials having ethical issues with whether to eat or not other animals, our ancestor ate whatever they found where they lived. If they lived in cold climates, they sure ate a lot of meat and if they lived in warm climates where more vegetables, fruits and tubers grow easily then they ate them as well. Tools and skills to cook made possible that we exist today.

That's all I had to say in this post, I hope you found it interesting and don't miss the next part about what our ancestors ate during the Neolithic until the beginning of the common era!

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