The Catholic Church teaches that out of earthly beings, only humans, and not animals, are persons and therefore many rights, like the absolute right to live, are enjoyed only by humans.
2417 God entrusted animals to the stewardship of those whom he created in his own image. Hence it is legitimate to use animals for food and clothing. They may be domesticated to help man in his work and leisure. Medical and scientific experimentation on animals is a morally acceptable practice, if it remains within reasonable limits and contributes to caring for or saving human lives.
2418 It is contrary to human dignity to cause animals to suffer or die needlessly. It is likewise unworthy to spend money on them that should as a priority go to the relief of human misery. One can love animals; one should not direct to them the affection due only to persons.
And notably, the above canons are placed in a chapter whose title is:
II. Respect for Persons and Their Goods
If I’m not mistaken, this position stems from the definition of “person” proposed by Boethius, which is most commonly accepted among theologians:
A person is an individual substance with a rational nature.
The problem is that some modern scientists claim that according to the new research we must consider some animals, in particular the great apes, as self-aware and intelligent, and therefore persons. They assert that these animals are also capable of self-control, planning, abstract thinking, mental time travel, comprehending past, present and future, empathy, establishing relationships, etc. They assert these animals are sentient.
Therefore these scientists claim these animals should be granted the right of bodily liberty, bodily integrity, and must not be considered properties of other people.
By such mentality denying animals human rights is an example of an unmadated supremacism, chauvinism and discrimination, similar in nature to the historical discrimination of people born as slaves and later of people of other races.
Yet under the Church’s teaching it would seem impossible to classify these animals as persons. Given these scientific claims, seemingly fulfilling Boethius’ definition of a person, how does the Catholic Church defend its teaching with regard to animals not being persons?