This article http://newscenter.berkeley.edu/2014/12/03/reasoning-skills/ offers an interesting approach to understanding the neurological differences between creatures like ourselves and our closest primate relatives. It suggests that our reasoning capacity, which involves the ability to do second order reasoning (linking unlike relational groupings in a relational way) hinges on certain brain developments which evolved in our species as we transitioned from a more primitive ape-like creature to what we have now become:
Relational reasoning is a high-level cognitive process in which we make comparisons and find equivalencies, as one does in algebra, for example. First-order comparisons identify the relationship between two items or activities in the following ways: semantic (hammer is used to hit a nail); numeric (four is greater than two); temporal (we get out of bed before we go to work) or visuospatial (the bird is on top of the house). Second-order or higher-order comparisons take this a step further by equating two or more sets of first-order relations (a chain is to a link as a bouquet is to a flower).
“It’s not just that we humans have language at our disposal. We also have the capacity to compare and integrate several pieces of information in a way that other primates don’t,” she added.
In reviewing dozens of studies — including their own — that use neuroimaging, neuropsychology, developmental cognitive and other investigative methods, Bunge and fellow researchers concluded that anatomical changes in the lateral frontoparietal network over millennia have served to boost human reasoning skills.
"Given the supporting evidence across species, we posit that connections between these frontal and parietal regions have provided the necessary support for our unique ability to reason using abstract relations," said Michael Vendetti, co-author of the study and a postdoctoral researcher in neuroscience at UC Berkeley.
In a sense this also shows a demarcation point between science and philosophy. Where science gives us a way to understand how the mental mechanisms we rely on in our daily and professional lives are made possible by brain functionalities, philosophy offers a way to understand how our intellect, our grasp of things, works in us. That is, an account of those features or elements in our mental lives (what goes on in us when we think about and understand things) which make up our grasp of the world around us (our subjective placement in the objective world we recognize as our milieu) requires a conceptual inquiry more suited to philosophy than science. Of course, the two cannot be divorced because science surely requires conceptual clarity in the formulation of its hypotheses and theories while philosophy depends on agreement with the best available empirical knowledge (scientific information) if it's to provide viable conceptual accounts.
If science can tell us what brains have to do to generate the elements we experience in our mental lives, and how our brains got that way, philosophy is needed to understand what the mental features caused by our brains' being "that way" actually consists of. That is, we need to know what's going on with us when we conceptualize the world around us in terms of spatial and temporal pictures and plan our actions, within that layered context, and evaluate the possibilities accordingly. Only with that sort of account can we know just what it is the brain's structure and functional behaviors make possible.
This, I think, points up quite clearly, the dividing line between science and philosophy. While the two are historically linked (science was once thought of as "natural philosophy" or philosophy of the natural world) and it seems quite clear that today's systematic sciences grew out of more hit or miss kinds of philosophical inquiry, the methods of modern science are radically different from those of modern philosophy. How so? Science, all the sciences from the "hard" ones to their "softer" cousins, depend on empirical information collection and organization via theories as explanatory strategies. But, while philosophy is also engaged in a process of explaining (sometimes via theories or theory-like descriptions), it's job is not to collect information about the world around us and produce explanations based on that but to work with the information we have (either through our day-to-day experience or as provided to us by the sciences) to devise explanations of how the more basic explanations cohere.
If science has, as its job, the development of new explanations to replace older ones, or augment them, philosophy's job is to explain the explanations themselves, in terms of how they combine and interrelate. It's to understand our understandings, one might say. That's why philosophy attends to epistemological questions along with the practical operations that constitute our lives: how we know (epistemology, logic) things (metaphysics and the sciences) and how we value the things we know (ethics and aesthetics).