>>>Then you're not listening. Speciation -- a basic concept of the theory of evolution --- explains how one population splits in two, with one branch evolving in one direction (in this case into humans) and the other in another (in this case into chimpanzees and bonobos). You should do a little reading about speciation before you come on this thread and tell us that scientists have given you no answers.>>>
Scientists have given no answers as to the aspect of HUMANS. Why do HUMANS and no other creature CONTINUE to grow intellectually, while other species remain just as primitive as they were 1,000,000 years ago? Maybe they change physically to adapt to their environment, but humans continue to expand.
Two answers that are mutually exclusive:
A purely scientific view may be that the ability to intellectually expand is an emergent property from evolution. At a certain point, a species evolves the ability to intellectually expand. We are the only species on this planet to have evolved that capability.
Alternately (and non-scientfically) the ability to intellectually grow is the gift that God gave man and was the specific act created us in His image. Evolution is how we took our physical form. The gift of intellect is our creation.
Well, the answer is that it's more complicated than that. Human brains are big, but they haven't gotten any bigger in a long time, because if they were bigger, infants' skulls couldn't fit through a woman's pelvis. And women can't have significantly larger pelvises and still be able to walk bipedally. Now that may no longer be the case given the widespread availability of caeasarian sections, but we'll see.
Having a large brain is always a trade-off -- with only a limited amount of body mass available, you have to allocate a certain percentage to the digestive system, to muscle mass, etc. These percentages go up and down in response to selective pressures.
I think that the current hypothesis is that at some point the human brain reached an evolutionary tipping point. Add in human speech, toolmaking & symbolic manipulation (writing) and you have the beginnings of an intergenerational repository of knowledge. So while not all human beings are as bright as Isaac Newton or Albert Einstein, the sum of all human knowledge continues to expand.
Apes have the ability to stand on their hind legs. Doing so free's up the hands for other tasks. Some time ago in West Africa, an extended warm period forced some apes out of the trees and onto the savannah, where walking erect probably allowed the brain to remain cooler (and gave certain advantages in predator early-warning). So human intelligence may have rapidly evolved as a consequence of a behavioral adaptation brought about by a sudden environmental shift.
Perhaps the capacity for intellectual growth is a trait, and not an inevitability. For example, Marxists have shown little or no capacity for intellectual growth, merely the mimicry of the outward appearances of such.
How do you know? Talked to a porpoise lately?