First some excerpts that are more coherent than the original, then some history of my own ...
Ideas and Trends - When Human Rights Extend to Nonhumans - NYTimes.comIf we're still around fifty years from now, this will be an obscure event on a history exam, with the context of "of course this is obvious".
... the environment committee of the Spanish Parliament last month to grant limited rights to our closest biological relatives, the great apes — chimpanzees, bonobos, gorillas and orangutans.
The committee would bind Spain to the principles of the Great Ape Project, which points to apes’ human qualities, including the ability to feel fear and happiness, create tools, use languages, remember the past and plan the future...
If the bill passes — the news agency Reuters predicts it will — it would become illegal in Spain to kill apes except in self-defense. Torture, including in medical experiments, and arbitrary imprisonment, including for circuses or films, would be forbidden.
The 300 apes in Spanish zoos would not be freed, but better conditions would be mandated...
... Mr. Singer ... left out lesser apes like gibbons because scientific evidence of human qualities is weaker, and he demanded only rights that he felt all humans were usually offered, such as freedom from torture — rather than, say, rights to education or medical care.
... even in democracies, the law accords diminished rights to many humans: children, prisoners, the insane, the senile. Teenagers may not vote, philosophers who slip into dementia may be lashed to their beds, courts can order surgery or force-feeding.
Spain does not envision endowing apes with all rights: to drive, to bear arms and so on. Rather, their status would be akin to that of children.
... Spain’s Catholic bishops attacked the vote as undermining a divine will that placed humans above animals. One said such thinking led to abortion, euthanasia and ethnic cleansing...
It's a more than mildly interesting question.
Eons ago I wrote an ambitious essay for a philosophy class; I attempted to create a species-neutral mechanism for assigning rights and privileges. Every scheme I came up with, and those I've read since, had uncomfortable consequences. It wasn't merely that one ended up giving lesser rights to my species than to better behaved robots and aliens, the rights of many impaired humans overlapped with not only apes, but also cats, dogs and squirrels.
In a later medical school essay I accepted the inevitable, and wrote that all ethical systems are merely post-hoc explanatory frameworks for enforcing and extending biologically and culturally evolved mores. The species-specific assignment of rights then is not a challenge to reason, it's merely politics.
Still. Many things that were once accepted mores are now despised. Even the homophobia of my youthful culture is passing into the night.
We know the road we're going down. If our civilization survives, sometime in the next century we'll grow our protein from tissue cultures, not from animals.