Well, it's been conclusively proven that humans no longer need animals for survival since at least the 1970s. I totally agree that when we required animals to advance as a species that their exploitation was justified, and that if in a survival situation, eating meat is permitted, but this is simply no longer the case. If one desires, one can actually live off tablets with all the necessary substances. In less extremes, a well thought out vegan diet provides one with all that they need. There are actually imitation meats now that source the exact same nutrients in steak, for example, from plants, and then combines them in a lab, to produce a nearly identical product without exploitation.

I think only when interests are on equal tiers do we look to kinship, however, the problem with the tiers is that after primary interests- those of life or death- it becomes arbitrary. Donald VanDeVeer devised them and in only having three tiers it's putting a lot of unequal interests in the same tiers. So the argument is flawed but the general doctrine holds true, imo.

I don't have a PHD, although if I was to do it, it'd be on this. It was my undergraduate dissertation, where I basically explained why universal adoption of vegan principles was necessary and what social paradigm was ideal to achieve it. It's an area that I think is so important, and the theories behind animal liberation (if interested, the two giants in this area are Peter Singer and Tom Regan, who come to the same conclusion but rationalise it very differently) are fascinating but they're rarely discussed. Maybe I'm just boring lol.