There are some good essays in here on how well humans can think about how non human animals think, as well as how we think about ourselves using animals as symbols. The most interesting essays for me were deconstructing anthropomorphism (though I came to this book for the essay on the intentional individualization of elephants for conservation messaging purposes).
Sandra Mitchell lays out a nicely plotted description of the logical dilemma around anthropomorphism that is well summarized in her opening paragraph "anthropomorphism is neither prima facie bad or necessarily nonscientific. It can be both, but it need not be either." It's certainly true that we commit an error in thinking when we try to attribute mental states to non-human animals that are identical to our own and ignore relevant differences between species that may influence whether or how a different species perceives and thinks about the world. As Mitchell points out, this is philosophically still a problem in attributing mental states to other humans, as we can never actually know the mental interiority of anyone outside ourselves. Thus we should rely on empirical evidence to substantiate our hypotheses that similar behaviors between humans and, say, chimpanzees are attributable to similar internal mental states and similar cognitive mechanisms and not explainable by simpler/non-rational psychological mechanisms (a la Morgan's canon, covered in the preceding essay and which foils nicely here). She then gives a very brief description of a series of experiments by Povinelli et al suggesting that chimps (and by implication all other non-human animals) have at best weak theory of mind. This one set of experiments though doesn't test ToM in chimps very well though - a raft of other studies before and after show much more evidence for complex ToM in chimps. Crucially, these are experiments that take into account the idiosyncrasies of chimp behavior/cognition (not trying to evaluate whether chimps show human ToM but something more appropriate to/evolved for chimp ecology instead) and which don't test how well chimps understand human testers but rather how well they understand other chimps. It always struck me as profoundly unreflective that human can deride anthropomorphism as inappropriate b/c we can't know other species' minds but can then also expect chimps or other animals to understand human minds in experimental tests. Anyway, Frans de Waal does a good job of summarizing the limitations of previous attempts at empirically testing non-human animal intelligence. We've come a long way on this but have much further to go.
What was a surprisingly interesting essay was the Victorian Lab Animals essay. I had no idea about the history of philosophical thinking around non-human animal cognition/intelligence. It was very interesting to learn about Darwin himself proposing intelligence and individuality in several species. And curious to see that subsequent debate over the physiological underpinnings of animal movement deriving either from some sort of immaterial soul/will or naturally explainable forces selected for by natural selection and shared amongst all species. The essay doesn't delve into this, but the implication is that when physiologists determined that we are demonstrably not animated by an immaterial soul, then some basis for ascribing moral value to non-human animals evaporated. I would be quite interested in learning more about the development of this thinking and the internal psychology of a Victorian vivisectionist who professes to love dogs while literally eviscerating them, vs the anti-vivisectionist advocates. Sounds like fertile grounds for novelistic exploration.