This is the second book I've read by Balcombe, an animal behaviourist of the right sort. By which I mean that he views animals with respect and empathy, in the same way, I surmise, as he views other members of his own animal species.
Essentially, this is the nub of the book. Balcombe eschews the idea of 'anthropomorphising' because in effect he shows (backed up by good references and citing) how time and again many of the 'higher' behaviours which we arrogantly assume are evidence of our unique 'humanity' - such as altruism, empathy, the ability to reason, language are in fact 'animalistic'. There is not such a clear divide between ourselves and the rest of the, particularly, mammalian and avian world, though Balcombe also shows reptiles, fish and even insects to be more advanced than we might suppose.
In fact, rather disturbingly, the idea cannot help but surface that our unique humanness may rather be a retrograde capacity to delight in the wanton infliction of suffering upon others, whether of our own species or of other, supposedly dumb (sic) animals. Balcombe posits that we may well have introduced the philiosophy of regarding ourselves as separate from other species in order to justify this brutality, to find an excuse for our cruelty towards other animals - and indeed, our cruelty, expressed across cultures, geographies and the centuries, towards individuals and groups of our own species, which the dominant cultural group regards as 'subhuman'. This ability to separate the human from the subhuman has been responsible for some of our most intense acts of racial cruelty.
Balcombe's well written, carefully thought through book ends with an impassioned argument in favour of veganism, on environmental grounds, as much as any other argument against the exploitation of our fellow, though non-human, animals.