From an ecological point of view, it would make sense if less meat would be eaten all over the world. However, this can’t legitimize a strict vegetarianism nor a basic veganism can be justified.
Of course. No biologist, no zoologist will dispute this. Humans are mammals belonging to the order of the primates and in this order to the dry-nose monkeys.
Actually, animal rights activists are concerned with all animals, from the great ape to the bee. In practice, their involvement is restricted to farm animals or animals which are kept by humans, ie to a very small percentage of the total of more than 1.3 million known animal species worldwide.
Like all vegans, they can not eat meat or other animal products such as eggs, milk and honey, and also no butter, milk chocolate, milk ice cream and egg noodles for example. However, there are many other rules.
Whether the cow is kept in intensive livestock farming or in a largely organic farm is irrelevant for animal rights activists. They reject any animal use.
The founder of modern animal ethics is the Australian philosopher Peter Singer, who developed the conceptual, philosophical and political foundations of the animal rights movement with his books “Animal Liberation” (1975) and “Practical Ethics” (1984).
The world’s most famous and influential organization is PETA (People for the Ethical Treatment of Animals), but there are countless smaller and larger ones dedicated to the animal rights.