‘The Prehistory of the Mind:the Cognitive origins of Art Religion and Science’ by Steven Mithen deals with the evolution of the human mind from the common ancestor with the apes six million years ago to the most modern humans who appeared sometime between 100,000 and 50,000 years ago.
The author is a British archaeologist.
His thesis is that all previous versions of humans had intelligence, in some cases highly developed. The earliest versions had general intelligence, social intelligence (also possessed by chimpanzees) and natural history intelligence. Later versions added technical intelligence and finally language intelligence.
It seems that the Neanderthal had all of them and a brain size at least comparable to modern humans.
However, Mithen’s fundamental contention is that the intelligence of the distant ancestors operated like a Swiss Army knife ie. one tool at a time and one use for that tool.
The real leap made maybe 50,000 years ago, was what Mithen describes as “cognitive fluidity”. That is the ability of all facets of the mind to integrate and operate as one. This lead to imagination and hence complex specialized tools, art, religion and science. Agriculture was made possible by this revolution in the brain.
Imagination he says is based on use of metaphor and analogy. One can readily see it in art and science and consistently in language.
He described the evolution of the mind and various intelligences as similar to development of a computer where facets are independently designed and added to what is already there to insure each works. When all work well independently they are integrated.
This book is academic in nature, and a stiff read, but if the subject interests you the treatment is fascinating.