Why did humans, out of all the vast variety of living creatures on earth, become the only species to develop such large and complex brains?
Though somewhat intuitively – I have to admit – the answer to this question seems to me rather clear and straightforward: because they were the only creatures who had a use for a large brain.
Besides the proportionately extraordinary size of their brains, what is that one other feature which radically differentiates the homo genus from all other animals? It is bipedalism: the ability to walk on two legs. Shouldn’t these two peculiarities of the human organism structure be intricately interconnected? I believe they are. I believe that bipedalism did indirectly yet determinedly cause the homo brain to grow.
Whether in order to see in the distance while walking through the tall grasslands of eastern Africa, or to wade through shallow waters, or for whichever other reason out of the many proposed, by some accident or another, some ancient apes did take that major evolutionary step to stand up and walk on two legs, giving thus birth to our unique genus.
First of all, this new ability led to the formation of the favorable physical mechanics which allowed humans to develop and sustain large brains for a number of different reasons… The most obvious of them is that bipedalism is an immensely more economical method of motility than quadrupedalism; all the energy surplus saved from moving could be now used for other applications, such as building a brain. Another reason is that the upright spine developed to make two-leg walking more efficient could support the increased weight of a skull containing more stuff. But other than merely creating the mechanical possibility for large brain development, bipedalism did something of far greater importance: it created the very need for having a large brain in the first place.
By standing up and beginning to consistently walk on two legs, those ancestral proto-humans were accidentally left with two spare, useless limbs. Remaining idle, the already exceptionally dexterous front limbs of apes probably didn’t take long before they got adapted for a whole new, revolutionary use. Via a process of individual experimentation and transgenerational natural selection, the two extra limbs were transformed into the most sophisticated handling instrument evolution on earth has ever devised. Those apes possessing this fabulous instrument were now endowed with the ability to manipulate their environment in such a subtle way that no other animal previously could. This ability opened up for them a whole new vast realm of information; and, together with it, it created the need to process, store, and communicate this information. The erect, adroit apes were in need of a powerful data processor.
Consider this hypothetical experiment… A crazy scientist takes a pack of dogs and implants into their skulls brains of equivalent power to the ones of humans. What would be the first thing those super-intelligent canines would go about doing? Perhaps they’d want to build some dog houses for themselves. They choose a nice spot for founding their dreamed-of dog settlement; they split and scout the place carrying back a good load of sticks and stones in their mouths… and then they have to put them up together… They try but soon realize that their mouths and paws are not sufficient means for putting up a standing structure of any kind. They give up and go about doing what they can instead: chasing cats and waiting for humans to feed them.
However much they tried, it is very doubtful they found any single practical application for their additional information-processing capacity. Their brain power before receiving the implants was already as much as was needed to provide for whatever activities their bodies have been designed to carry out: running, jumping, chewing, burying bones…
Perhaps they would try to direct their new augmented reasoning power towards theoretical ends. They could, for example, fancy to categorize and study the chemical signatures of all the different scents their noses are capable of perceiving. But, to start with, how would they even know that there is such a thing as a chemical structure of matter if not having come up with a microscope first? How could they ever sit down and calculate the π without having observed a circle before? And how could they ever observe a circle without drawing it themselves? In short, why would they ever need a theory if not for better understanding novel observed phenomena?
Would they maybe come up with some new barking and howling frequencies to expand their vocabulary? What would a single one new idea they’d want to express be?
I think the point’s been made pretty clear: Animals seem to develop mechanisms according to their needs. A fish wouldn’t develop wings. A bird wouldn’t develop gills. A herbivore wouldn’t develop sharp teeth. Likewise, a creature which has not been endowed with any hand-like apparatus to elaborate objects in their environment wouldn’t develop a large brain.
Take a dolphin and give her a brain a hundredfold more powerful than a human one. Would that enable her to do anything different than she did before? I suppose not. The only thing that would probably change is that she would die in a matter of a few hours due to not being able to provide for her increased energy needs.
So did the homo brain evolve in parallel with hands. When they first managed to erect a stone pile, they became acquainted with a whole new concept which they named a ‘pile’. Acquiring the ability to hurl a stone, they needed to use some brain force to calculate the trajectory of a projectile. By being able to draw a circle with their finger on the sand, they came to determine the shape’s defining characteristics such as a diameter and a perimeter, and eventually even calculate the relation they have to one another.
By becoming bestowed with the efficacy to elaborately manipulate things around them, they gained access to a vast new supply of data previously concealed from life. They were in an urgent need of a powerful hardware appliance to run the appropriate pieces of software needed to deal with this new torrential data stream, such as mathematics to process the information, memory to store it for future reference, and language to outsource it among them and take better advantage of it.
We also see the same process repeating itself today, but on a much larger scale this time. When humans collected a sufficient amount of information from their environment to unlock the mysteries of energy and take advantage of it, they naturally set forth to create stronger and apter, artificial, external devices – or extensions of their hands – which enabled them to manipulate their environment in ways and scales unimaginable theretofore. This industrial revolution gave rise to a new need to process vastly greater amounts of information. Traditional, genetical evolution could not do the trick this time. Just like they created external, artificial hands, now they had to create external, artificial brains to deal with the data generated.
