The Relativity of Mind
Just as the physical universe at any given time has no absolute central point from which all others take the measure of their positions, so the mental universe has no "highest" or "most central" mind, against which all others are measured, "higher" and "better" than all others. As all points in the physical universe at time t0 are equidistant along a 4th dimension of time from their origin in the Big Bang, none any more central than another, so no type of mind is "inherently superior" or "inherently inferior" to any other in a genetic sense, or in the sense of more or less intelligence. Where minds differ from one another is in type. That is, at least potentially, every species is as intelligent as every other, but a given species' type of mind differs to greater or lesser degree from that of any other species. All species existing at any given time are equally "evolved," since all have come the same temporal and evolutionary distance from the beginning Earthly life. But each form of life has its own distinct niche in the living world, and its mind is tailored for survival in that niche, and thus differs, at least to some extent, from the minds of creatures of any other species. The degree to which we accept other creatures as having as much intelligence as we do is really just a measure of how different the niche for which they have been evolutionarily tailored is from our own. We like, or at least are interested in, the mental lives of other creatures to the degree that their niche resembles ours.