Given that the neolithic revolution happened in more than one place, I don't see how it could be a very significant filter.

But it probably wouldn't have happened anywhere if there wasn't an interglacial period. My point is that intelligent life is unlikely to develop a technological civilization unless the planet they're on allows them to achieve very high population densities (e.g. by artificially growing more food than otherwise available), which ISTM that Earth before the interglacial period didn't.

Or are you referring to "civilization" in a sense not achieved by the Incans or the Aztecs?

From what I read on http://en.wikipedia.org/wiki/Aztec#Economy they definitely do count as a civilization by my standards.