It is rare that I find a book eye-opening. Some books are entertaining, others usher visceral emotions, others transport you to into strange lives, some do it all; some books nudge your brain in a strange new direction, and some others add a tiny little brick to the always crumbling, always growing building that your knowledge is. But it's rare that a book is eye-opening in a way that you feel that your mind has been altered irrevocably. This is one of those books.

Bear in mind that I met this book half-way already. I find Descartean thinking that animals are bloody automatons with only the appearance of emotions silly. I don't need convincing that animal consciousness is real, that many animals have complex minds, with wishes, desires and feelings. The evidence, both scientific and personal, is overwhelming, and this has led me on a lifelong quest to reduce my footprint into animal suffering. Despite all that, this book pushed me, challenged me into questioning my prejudices. For example, a fundamental one has been, even if I haven't quite articulated it that frankly, is the one-sided nature of the relationship between humans and animals. Even being aware that many of the supposed differences between humans and animals are a matter of degree and not kind, I'd never let go of the supremacy of human beings; I'd just believed that it gave us obligations towards their welfare, not subjugation. This book takes a battering ram to that school of thought.

But first things first. The book starts off by laying the ground for making a key argument, a persuasive one, one of many. That everything that has been done to show animals' proficiency in language, even the things that show them in a good light, like signing apes and maths solving horses, is flawed. The key insight is that these experiments aren't showing what they think they are: they're merely showing how good these particular animals are at that particular artificial language constructed for that experiment, not how good at their own intra-species language they are. The author draws on her background in philosophy to talk about the definition of language, and the challenges with necessitating human language for having a consciousness. Another key insight: language is not static; it's often and perhaps always only given its truth by use in a social context. A followup insight: to study animal language, their context is important, and this cannot be achieved in a lab or a zoo, but only by listening quietly and respectfully.

The book draws on so many, so many examples of brilliant animal communication, and I can't recall them all. For me though, these examples add colour to the fundamental insights the book offers, but for you, even if the insights don't resonate, the examples might be interesting to read. From the pool of animal communication studies, there is evidence that some animals have open ended language, recursive language, grammar, structure, metalanguage and pretty much everything that's often ascribed to being unique to human language. The insight is that studying animals in their own context - playing their own 'Wittgensteinian language games', as she calls it - is what will unlock more of the features of their language.

There are examples of humans who've successfully achieved egalitarian relationships with animals, not as owners, not as masters, not even as kindly guardians, but as members of their social group, understanding their rules, but drawing their own boundaries. The insight from this: egalitarian communication between animals and humans is possible, difficult but possible. A more abstract series of insights reveal the biases that have coloured studies of animals - that animals are instinctual (i.e. Descartean automatons) unless proved otherwise, while humans are free thinking unless proved otherwise. Ethnographic studies of animals and human psychology are breaking down this false dichotomy at a rate of knots.

In the second part of the book, the author draws on all the insights we've gleaned from animal language research, and branches off into deeper, harder, challenges questions. Do animals have a sense of fairness and justice? Empathy? Can animals and humans work together to build more equal shared communities? The answers are tantalising. I'll be thinking about this book for a long time to come.

For the negatives, some might find this book off-putting because it might seem polemical. For instance, its deliberate choice to call animals communication language, despite the lack of consensus. I see that as necessary for a paradigm-challenging book like this one, but you might find it not unbiased. The book is doing this in a self-aware way, for instance, when it challenges accusations of anthropocentrism, arguing that it's not an unbiased position at all. If you stay patient with any sections you might find polemical, and ride the changes of pace - the animal studies examples are easy to skip through at lightning speed, but the more philosophical sections harder to absorb - you'll have a rewarding, and hopefully just as eye-opening, experience.