In literate societies you might assume the task of reconstructing the past to be different. Such is not substantially the case however. When you realize that words themselves, the record of which defines the beginning of human history, are a form of tomb, the possibility for a knowledge ignored by scientists is extant. Reality that is captured in words is AT BEST, only the past, never the present. So in a sense you are still not able to access an eye-witness account. Not keeping this aspect of linguistic reality in mind, hinders any apprehension of a real present, much less, what might have been a past reality.
The recognition of the reality of tombs allows a kind of knowledge, if that recognition is persistently pursued. The fresh, unbreathed before, air is in realizing the difference in horizons, in distinctions, like that between, 'there is no life after death', a binary phrase, and, the words of Jan Cox, only superficially similar, "there is no evidence of life after death."