Daphna, on Dec 15 1997 you posted in Serendip Forum,

Jake, thank you for making your comments on meta-thinking so clear...I did fail to understand what you originally meant by the term meta-thinking. To think about thinking. OK, now where will that take me?

Daphna, Man is the only living organism that has evolved sufficiently as to be capable of meta-thinking. Aristotle probably wrote on this subject, but he could not know that this is an evolutionary attainment. He apparently was so taken by this impressive capacity of human beings, that he attributed it to a special godly manifestation.
I am just stating that animals other than man, whether rational in different degrees or not, have not evolved to such degree. If dolphins are capable of meta-thinking, they are not so at human's level. Should there be a race of man-looking organisms incapable of meta-thinking, they would be classified as 'sub-humans.' Please tell me if this is clear and where does it take you to.

...how we think?

There are three basic types of thinking.
The simplest, autistic thinking, which is the common day-dreaming, just recalling. The second, non-creative realistic thinking, such as is used in simple dialogue, and then creative thinking, the fount of scientific and artistic outpour. You are interested in this latter specific mode of thinking, which is also an impressive evolutionary result. Man (woman included) has developed specific brain areas for such effect.
Everything related to thinking, such as memory and learning, both immediate and long-term, is effected by specific proteins -therefore, by genes.

...where we think?

Depends on the circumstances and personal preferences. ...what we think?

Autistically, we just recall thousands of recent or past experiences. Non creatively, yet realistically, we think about the subject of the dialogue in which we are engaged. The dialogue may be 'internal,' i.e, with ourselves, when we are weighing possible and preferable courses of action.
Creatively, well, I suggest reading my post on Parody and Dreams.

...why we think?

I believe that there are inherent properties in the elements --starting from hydrogen-- that confer living organisms their capacity to be created and evolve. {A post of mine, 'Quantum and Love,' waxes lyrical on this theme.}
Fundamentally, it is the electrons and their electrical charges that allow the creation and subsequent development and evolution of life forms. A limited number of elements are appropriate for such physical phenomena. There are many elements that organisms can dispense of, i.e, live without them, such as lead. They exist because of the stringent physical laws. Now, beside the 92 natural elements, several others are man-created (artificial), most being very unstable and even radioactive. The common explanation is that the the latter are too large to support nuclear cohesive forces. Yet, theory says that element 114 will be impressively stable, due to the peculiar constellation of its electrons. If so, it might become "the element of the 21st century." It might impact civilization in unforeseen ways.
Thus, Daphna, we think because we are made of the stuff that eventually manifested its intrinsic endowments for the creation of our species, Homo sapiens --a unique thinking and meta-thinking result of long-drawn evolutionary --physico-chemical-- phenomena.

...Yes, if we could answer these questions about thinking, we might actually approach 'truth'...It would serve to take us to the pinnacle of knowledge, for to know these things would answer the question, why are we here as we are, seemingly different from other life? Perhaps cats and dogs do not concern themselves with such thoughts of this nature and perhaps it is the thing that separates us from them. If so it is a fine line since cats do think and so do other animals. As a fine line it also could mean that any animal could join us on the "human level" as some believe the dolphin has already. This fine line brings up some serious moral questions of how we treat other life on this planet that we share. Many things to think about, on top of thinking about thinking.

This is abstruse language, Daphna. Analytic and Linguistic Philosophy rejects this type of musings, accepting only alethic subjects for dialog. I suggest you read my post on Linguistic Communication.
I am not being pointlessly critical, just avoiding pointless discourse. Please remember that I am a contributor to philosophy basically in what pertains to brain, mind and thinking, explicitly avoiding metaphysical musings.