The plains of Africa were covered with dense forests 3 million years ago. All this vegetation
was consumed by giant antelopes, monstrous pigs, lots and lots of elephants and rhinos.
They were hunted by sabre-toothed tigers, giant pachycrocuta hyenas and Chasmaporthetes hyenas,
also known as running-hyenas.
Our ancestors - gracile Australopithecus -
were also actively participating in this zoo.
They could walk on two legs but did not produce any hand tools.
They were plant-eaters and the size of their brains was comparable with modern chimpanzee's.
Two and a half million years ago, until then a relatively small Gelada-Baboons
managed to grow to a magnificent size of around 60 kg
of weight and up to a meter tall in the crest! They had long fangs and were able to cooperate in large packs.
They were aggressive and well organized.
To make things worse, their diet was identical to gracile Australopithecus.
Both ate grain and seeds in a bush.
Australopiths had the only 30kg of weight and 1 meter high
but while standing up on two legs.
Expectedly enough, the environmental race was lost.
Giant Gelada - 1 : Australopiths - 0.
Most of their species vanished without a trace...
But some were able to adapt to the new environment.
There were 2 different ways to achieve this.
One way was to consume dry, nutrient-poor food such as sedge, tubers and nuts.
It was hard to digest, so there was no much competition for it.
This type of australopiths is named Paranthropus or robust australopiths.
Another way was to consume flesh.
Luckily enough, there was an environmental opportunity to start doing so.
2.5 million years ago the climate started to change. It became colder and drier.
The thick bush was replaced by grassland savannah.
Giant ungulates (or, so-called, hoofed) animals started to die out.
Their place was taken by new species.
These looked quite similar to modern antelopes, warthogs, zebras, elephants and rhinos.
Large predators had to follow their ungulate contemporaries.
Giant hyenas and sabre-toothed tigers in Africa were extinct.
Their place was taken by modern leopards, lions, cheet ahs, spotted hyenas, jackals and African wild dogs.
For a short time period, while fauna was changing, the ecological niche of predators and scavengers opened up.
The vacancy was immediately taken by early Hominids - our ancestors -
who used this opportunity while fleeing from the deadly competition with Giant Glades.
It's much more difficult to acquire flesh than plants. Normally, no one wants to be eaten.
The flesh tends to run away or even fight back.
It requires some convincing, so it's necessary to apply some intellectual effort:
• hunting activity must be carefully coordinated
• You need to plan ahead • You need to gain and accumulate experience
Since our ancestors were mainly vegetarians,
they had no sizeable claws or fangs, so it was imperative to start using wooden sticks and stone tools.
So you have to learn how. And that's where the complex brain is required.
On the other hand, flesh provides more calories if compared to plants or seeds.
You have a choice - you can consume a lot of plants or a little bit of meat to feel full.
Let's compare how a cow and a lion behave:
a cow pretty much spends all of its days chewing grass, while a lion lies in the shade enjoying himself.
Our ancestors have certainly chosen the right way of life!
Nowadays every household has a comfortable sofa.
All the spare time you get can be spent on socializing and learning new things.
Which works as another incentive to develop the brain even more.
Finally, plants are simply harder to chomp on. You see, a plant cell has a cellulose wall while the animal cell doesn't.
That's why plant-eaters always have larger jaws than predators.
So the jaws of our flesh-eating ancestors started to reduce in size.
The relative density of teeth, bones and muscles is two times higher than the relative density of the brain.
As a result, the reduction of the chewing system by 1 cubic cm
allows increasing the brain volume by 2 cubic centimetres.
While keeping the overall mass of one's head the same.
And that is important because both the height and the spine size stayed the same.
So as you can see, while the jaws were only reducing a little bit, the brains size was skyrocketing!
Yes, the brain growth was a necessity but there were also favourable conditions for this to occur.
And approximately 2 million years ago, the brain of first hominids who were actively hunting and
producing stone tools - was already one a half times bigger than their predecessors - australopiths.
And what about those Giant geladas and Paranthropus?
Well, Glades met our ancestors next time when they had already become smart and armed...
which lead to Gelades extinction approximately 1.5 million years ago.
Only one small species has survived hiding in the desolated mountains of Ethiopia.
Our vegetarian cousins - Paranthropus – managed to last much longer
but still disappeared around 1 million years ago.
They were unable to withstand the competition against small rodents and new types of hoofed animals.
While our smart and capable ancestors left Africa but that's an entirely different story...