Why are elephants higher on the hierarchy than eg pigs?

They're a keystone species, have culture and language (probably older than any human one), they mourn their dead, and on and on...

Pigs are smart too. I don't know about on the same scale as elephants though. Elephants are also very social and long lived.

I try to cut pig products out of my diet because I can't kick this comment someone said to me once, "Pigs. As close to eating humans as you'll get".

I know many humans who are not very social. Is "very social" a prerequisite for right to live?

No, it's a proxy for intelligence and higher forms of conscious awareness. There's no such thing as right to live for non-humans - if the world stops eating pigs, how many do you think would be alive? That applies in nature too where survival comes down to fitness and luck. But the higher the life form, the more human-like it is and the more humanely we should treat them. Ants get different dispensation from cows, and cows from dogs. Dolphins and elephants should get better treatment still, but this is not currently the case.

Pigs are pretty cool too though.

Pigs are cheap and no one cares if you kill them.

Not seeing how pigs are different from dolphins

Have you tried Dolphin Bacon?

Apologies for being a bit pedantic, but I had never heard of the phrase 'keystone species' and went on to look it up. While an elephant could be (and perhaps is) a keystone species, I don't find that the status of being such a species is relevant for discussions on consciousness of animals because of what this term actually means and includes. Starfish, for example, could be considered a keystone species.

Not trying to be a jerk or anything (I'm also a vegetarian) but just wanted to bring this up in case anybody else was a bit curious about what the term meant or had maybe heard of the term before and was confused as to why it was included here. I'm also clearly open to a arguments discussing why a keystone species is inherently conscious.

Good catch. Keystone-ness has nothing to do with consciousness, of course. I was making a pile of reasons not to murder elephants.

To be clear my comment was intended to question killing pigs, not "not killing elephants".