Why we have so "special" brain?

I've listened the speech of the biologist, where she explained the question: is the human brain special and why?

https://www.ted.com/talks/suzana_herculano_houzel_what_is_so_special_about_the_human_brain

The facts about our brain are:

• It consists of about 86 billions neurones
• Human brain weight is about 1.5 kg it is about 2% of whole body
• But it requires about 25% energy that our body gets during the day from food

The facts about animal's and human's brains are:

• Human brain is not the largest in the nature. For instance elephant's or whale's brains are bigger. 
• The brain of the chimpanzee is equal in size to the cow, But the monkey obviously shows more mental behaviour because it has more neurones. 

Conclusion: the size alone does not play the main role in the "quality" of  brains. Main role plays the quantity of the neurones. And the quantity depends on neurones size. The less size of neurones the more them can fit into brainpan.

But apes have approximately the same size of the brainpan and the same size of the neurones. Why they don't have the same quantity of neurons and not so smart as people?

The answer - food. They are eating raw food about 8-9 hours per day but the energy is enough only for body and for small brain.

But human beings several 100 000 years ago became cook food on fire. From the cooked food body is able extract more calories. So these extra calories helped to increase number of neurons!