Science, religions and academics have poised this question for hundreds of years and now, with new breakthrough research we have the answers.
New testing techniques now allow us to test the rehydrated saliva of each of our ancestral species to test for the presence of a streptococci bacteria that was present due to the presence of large amounts of starch which it fed on.
There have been so many theories as to what foods out ancestors ate to aid in our development and especially the development of our big brain.
Was it all the fat from the meat we ate?
Was it the starches we started gaining access to through the ability to form the alpha amylase enzyme in both our mouth and gut?
Was it the invention of fire that let us eat more calories from novel sources that we would not be able to digest otherwise?
One thing is absolutely for sure, we had to change our dietary habits for us to develop brains literally three times the size of our pre-human ancestors.
To understand the answers to these and a few more questions that we must ask, we’ll need to take a trip through ancient history up to the present, and when we say ancient history, we really mean it.
To begin we have to answer the question…
What Did Pre-Humans Eat?
Countless studies from around the world have shown that pre-humanoids ate most anything they could that grew in their geographical location.
This means that if they were in tropical environments, they ate fruits and other plant matter, but almost always fruits if they were available.
Those that were in the plains ate mostly cereal grasses, while those in mountain ranges focused on berries, cereal grasses, eatable leaves and other digestible plant matter.
Virtually all would opportunistically consume bugs and small creatures such as lizards when they crawled in front of them.
There are a few instances of evidence of the use of tools such as sticks that were used to stick into termite mounds to pull out the tasty bugs and pick them off the sticks and eat them.
A few brave souls would steal carcass pieces from kills of other animals and then run and share the prize with the group. This was of course dangerous as you can imagine. Stealing a piece of a gazelle from a lion or a pack of hyenas was about as safe as jumping off a cliff in the dark when you can’t see the bottom.
However, as you might have gathered from their different various diets, plants were the main course and other forms of proteins were at best snacks or steals.
Now, since these were pre-humans, what changed, in their diets, living environments or possibly even social structures that allowed them to take the steps towards becoming modern man?
Something certainly happened, but what was it?
Let’s take a look and put it all together.
One of the first things you have to look at is, when did an event happen?
If you see a certain result in history you should ask, when did that happen.
Why?
Because, you know the change that took place, then once you know when that change took place you can figure out what they did differently at that time and that might just be what you’re after.
So, the next logical question is…
When Did Humans Split Off From The Rest Of The Homo Genus’s?
The homo genus variety of species began to split off from pre-humans as early as about 1.8 to 2.2 million years ago.
Then the homo heidelbergensis began to emerge and it is believed that homo erectus began their dominance somewhere between 1.1 million years ago and as little as just 600,000 years ago depending upon who’s research you read, with virtually all signs of homo heidelbergensis having all but disappeared by that point.
There are a number of reasons they may have died out. Some claim climate change, or a natural disaster.
However, the most likely was that as nature evolves so must species.
This is to say that, when your environment changes in multiple ways, your species must adapt or be left behind.
If a newer and faster cheetah was to begin spreading across Africa, then their prey animals such as gazelles would either become faster or be hunted out.
These changes are generally very slow and take tens or even hundreds of generations, as such, the way it usually works is…
The cheetahs start adapting to get faster because only the fastest survive, the slow cannot catch prey. So, over many generations the genes from the fastest become dominant and as the genes go, so goes the species.
The gazelles begin to adapt to this in response because the slower gazelles get eaten and the faster survive and pass this characteristic on via mating.
Ok, that sounds cool, but what about humans?
Well, as an example. Let’s say the climate became either more arid or wet because we’ve always had climate change. Different plant species and animals (foods) would then become dominant, and others would die out. If you lacked the enzymes needed to break down and extract nutrition from these new calorie sources, then you would slowly starve and not be allowed to mate because you’re a weakling and cannot compete for mates. This thrn ensures that your genes are not passed on, which is the whole theory of ‘survival of the fittest’.
That’s just one example that you’ll later see is in opposite to the reasons we were able to develop our brains to become modern man.
However, using the food analogy, because we are discovering what foods caused our brain development then the next logical question would be…
What Did The Earliest Humans Eat?
They ate mostly the same things that the pre-humans ate with the exception that they started adding in novel starches from tubers that we will discuss in a moment.
How Do We Know Which Foods Early Humans Ate?
We can look at their remains and analyze the foods that were still stuck in their teeth and of course analyze their excrement.
Both of these have shown us that carbohydrate rich foods were the norm and most any form of animal flesh was a rarity in any type of quantity.
Then, as we discussed before, a new science has been developed that can study the bacteria in their saliva, gut and well-preserved excrement that shows the types of bacteria that were present.
You might say, so?
Why is that a big deal?
Well, just like your own microbiome (the bacteria in your mouth, gut and digestive system) certain bacteria eat certain things. If those things are prevalent, they flourish, if not, they die off.
This information will be critical to our discovery in a moment when we ask the question…
Which Foods Caused Our Brains To Grow And Develop In Size?
Let’s look at this both logically and scientifically so that both bases are covered. Because it really stinks when some science guy tells you this or that, but you’re thinking, what? That doesn’t make any sense.
We all know that glucose is the preferred fuel for the brain, and it likes a nice steady supply of it. So much so that, if we are eating the right number of total calories for our natural (non-steroid enhanced) bodies then our brain generally consumes around 20% of our daily calories as glucose.
We know that, so, that’s common knowledge which falls into the category of common sense.
It then would also be just common sense that in order for our brains to develop to such an extent that they required 20% of our daily calories as glucose, we would have had to have a consistent source of nutrient dense carbohydrates to feed this brain, or it would not be able to expand or continue to stay that size.
Vegetables and tiny kernels of grains that we ate right off the grasses simply don’t possess the quantity of carbohydrates that would be needed to grow a big brain.
There are only two other reliable sources that do have that many carbs. One is fruit and the other is starch.
The thing that many people don’t know is that our early fruits were not todays engineered, cultivated and cross bred foods that we have now.
No. As an example the banana was quite different as you can see in the picture, it was very seedy and contained very little fruit.
Image from (Warut Roonguthai/Wikimedia)
The fruit in this early banana was not the nice, sweet banana tasting stuff you have today. No way! This was a starch.
Have you ever eaten a really green un-ripened banana?
Well, imagine that, but several times starchier and you’d likely be pretty close.
The same thing with watermelon and other melons as well as cucumbers (which many forget are fruits) and a whole host more.
Then, there was a real problem with tubers that contained enough starch to fuel our brains such as early potatoes and yams before we cross bred them too.
They were very tough, fibrous things that were hard to chew and even harder to digest.
They contained the calories, but the calories were locked behind a vault of fiber.
Then came a magical time in human history, the age of fire!
It is thought that somewhere before the timeline we talked about earlier of 1.1 million to 600,000 years ago that homo heidelbergensis, the common ancestor for both homo erectus and the neanderthal began using fire to cook with.
Once we unlocked the secret of fire, we were able to cook these potatoes, yams and other tubers so that we could soften them up for better chewing and of course digestion.
This allowed us to absorb the bulk of their calories giving us a nice complex starch in a consistent enough quantity that we could begin to grow our much larger brains.
In warm and or tropical areas which early humans preferred to live due to our lack of fur, our ancestors had an abundance of starches from both fruits and tubers.
As for which areas of the globe this actually took place in there is still a lot of speculation. Since early man was primarily a plant eater, he didn’t tend to leave too many clues.
As an example: if you had a den of a meat-eating species, you’d have hundreds of bones laying around with their teeth marks all over them so you could positively identify the species that ate them based on the markings on the bones.
However, when a species is primarily a plant eater, they don’t leave behind much of anything at all. Maybe you get lucky and discover a fire pit or a few tools that they used to chop, grind or clean the foods, but that’s about it. All of the plant matter they ate rots and returns to the soil.
So, how did scientists figure out what foods our ancestors ate if there was not much evidence?
This was a massive challenge until just recently when scientists discovered that these novel starches stayed in the mouth for long periods (remember, they didn’t brush their teeth). This facilitated the growth of a unique streptococci bacteria that fed on the cooked, softened and partially digested starch (alpha amylase enzyme to the rescue).
With the ability to rehydrate their saliva the presence of this bacteria was found and then found throughout nearly all samples from these time periods but not before (in earlier species).
This proved conclusively that because of the invention of fire, we were able to eat starches that had previously been undigestible.
It was this source of consistent calories that allowed our brains to grow in size to meet our present day magnitudes.
With these findings, you now had the effect (the bigger brain), the time that it happened and the thing or cause that facilitated it just as we spoke of before.
So, with this evidence, it is now believed that our brains developed on fructose and starches from both fruits and tubers.
This makes a ton of sense if you think about it for a minute. It would not have been possible to grow our brains to this size on animal foods because they are nearly devoid of carbohydrates which is the preferred fuel of our brains.
Yes, of course we can function on ketones, but our bodies only switch over to this in time of need and the brain resists it until there is no other choice. If you’ve ever done it you know, most people get a headache when switching from carbs to ketones because the brain is resisting it.
We need a consistent source of slow digesting carbohydrate that is broken down into glucose over a longer period of time to provide a continuous flow of energy to our big brains.
Sources
1. https://www.pnas.org/content/118/20/e2021655118
3. https://www.sciencemag.org/news/2021/05/neanderthals-carb-loaded-helping-grow-their-big-brains
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC100085/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3069174/