There are at least two senses in which human beings can be called “naturally artificial”: being adapted for creation of and participation in niche constructed environments, and being adapted for creation of and participation in such environments despite an exceptional indeterminacy in the details of the niche constructed environments themselves. The former puts human beings in a common category with many niche-constructing organisms while the latter is arguably distinctive of our species. I explain how this can be so by developing (...) an account of supporting concepts of complexity, contingency, and content-openness, and show how to defend the position against a common style of objection by a single comparative case study: hermit crabs and their shells versus humans and their movable dwellings. Finally, I consider evidence that such a feature is indeed species-typical and evolved in human populations. (shrink)