[tsimionescu]

We don't know exact dates of course, but looking at the works of mathematics and philosophy that have survived, we know for sure that humans were capable of abstract thought at least as far back as 4-5000 years ago (for example, during the construction of the Great Pyramid of Giza), and very likely even 12-13000 years ago (during the construction of the megaliths at Gobekli Tepe, for example). Furthermore, we can assume that some time must have passed between the first threads of abstract thought and any achievements due to it that would stand the test of time, though I don't think we can put any hard estimates on this time.