Our physical sensations are probably the same as all other mammals. Things like physical pain, sleepiness, and hunger probably feel exactly the same to a cow or dog.
Our intellectual and emotional lives are probably little different than near-ish relatives, including not only humanoids like neaderthals and homo afarensis, but even primates like bonobo. These include the sensations of thinking, creativity, love, and mourning.
And not only close relatives. Dolphins have rich emotional, social, and intellectual lives.
Birds are cladistically far from us, but some are remarkably intelligent. Some live socially, can count, use tools, appear to mourn.
And the list goes on. How Smart Is An Octopus?
divers wanted to know whether octopuses—as suspected—steal fish from fishermen’s nets, so they set up a net complete with several fish, and settled back to watch. Sure enough, an octopus came and helped itself to the lot. Another octopus opened a jar containing food, while a third seemed disturbed by its reflection when shown a mirror.
I draw the line somewhere: hive beings. I think ant colonies are intelligent and have a sense of self interest, but their affective lives are truly alien.
In the long run there may be something like a Copernican revolution, but applicable to experience rather than astronomy. We may come to realize that our experience is hardly different than that of many others.
The human species has spent a lot of effort trying to find the “holy grail” that will confirm a qualitative difference and position of superiority above other animals. Neurobiological studies have failed to turn up a single property of the human brain that is qualitatively different from that of other species (i.e., that is not explainable within the common framework of comparative evolution). Specific focus has been placed on finding the basis for the uniqueness of the human brain among our closest primate relatives, that is, what separates us qualitatively from chimpanzees. But moving beyond the range of primates provides an important perspective on this effort. I have studied cetacean (dolphin, whale and porpoise) and primate brains for the past twenty years and there are compelling differences among them. Primate and cetacean brains are arguably two of the most different, morphologically, among the large mammals. These differences exist in cortical topography and cytoarchitecture and represent different ways of distributing and processing information in the brain. The cetacean brain not only possesses very unusual features but also a uniquely elaborated paralimbic lobe not found in primates. Despite these striking neuroanatomical differences driven by adaptation to different physical environments for tens of millions of years there is striking convergence in psychology across cetaceans and primates — not equivalence — but comparability and shared aspects of mind. To the point, cetacean and primate brains are vastly more different from each other than any two primate brains are. Yet, they are most validly understood as variations on a theme. Therefore, what would be the basis for arguing that there is a “bright line” between human brains and those of other primates? Compared to cetacean brains human and chimpanzee brains, for instance, are almost identical.
Try as we might we have yet to find any fundamental mechanism or principle unique to the human brain.