In San Francisco, as I recall, an ordinance has been passed so that a human cannot be an owner of a pet. They must now be registered as guardians. This is just a baby-step down the animal rights path, but undervaluing sentience could have quite a legal impact.
The physical laws tell us that all that there is, is a manifestation of wave phenomenon, thus the brain is a collective of wave phenomenon in itself, functioning within a seemingly endless sea of wave phenomenon - some of which may be a manifestation of other dimensions via resonance of superstrings or the effect of virtual particles or things we cannot begin to comprehend.
I assert that the brain itself is the transmitter/receiver that materializes a unity of consciousness which is the individual being. But the individual being cannot exist, materially, apart from the whole.
In the new age and Buddhist/Eastern mindset, the whole isnt a being, it is a greater collective which is influenced by the individual and vice versa.
In the Christian mindset the believer abides within the higher, non-material, being who has all the free will characteristics of consciousness, which I described earlier encompasses language, comprehension, love, sacrifice, self-awareness, etc.
This is a great mystery (and probably inconceivable) to people who are not Christian, but it is the fact of life to those of us who are:
I have other personal experiences which confirm this assertion, including feeling the spirits of both my sister and mother pass through me as their physical bodies went into a deep coma before physical death, night travels, and so much more.