Chimpanzees make love rather like humans do, but they do not usually run the risk of contracting syphilis. Not unless they are in a laboratory. An image that ever haunts me is the photograph reproduced in a Danish medical journal of the 1950s of a pathetic little chimpanzee dying of experimental syphilis, covered in skin lesions. I used it in my first two animal rights leaflets of 1970.[1]

Precisely because our chimpanzee cousins overlap more than 98 per cent of their genes with us they have been, and continue to be, mercilessly exploited in science. Their only protection has been their cost.

Chimpanzees share with us tool-making and tool-using capacities, the faculty for (non-verbal) language,[2] a hatred of boredom, an intelligent curiosity towards their environment, love for their children, intense fear of attack, deep friendships, a horror of dismemberment, a repertoire of emotions and even the same capacity for exploitative violence that we ourselves so often show towards them. Above all, of course, they show basically the same neural, behavioural and biochemical indicators of pain and distress.

Genetic engineering involving the production of new species of animals (sometimes containing human genes, as in the case of the Beltsville pigs and some cancer-prone mice) is making a nonsense of our traditional morality, based as it is upon speciesism. For centuries, and even today, the lay person has attached far too much importance to species differences, unaware that the boundaries between species are far from impermeable. Lions and tigers can interbreed and produce hybrids which are themselves fertile. Species of the Primate order (of which the human is a member) can also interbreed, although I know of no attested case, yet, of human interbreeding with any of the other apes: sexual attraction across species does not seem strong and mating could, at least in its natural form, prove highly dangerous for the physically weaker human partner!

Chimpanzees, gorillas and orang-utans, more than any other species, are intuitively recognised as our kin. Yet the implications of Darwinism - that biological kinship could entail moral kinship - are still resisted by vested interests and commercially motivated speciesism. It is interesting that in some instances, trading in chimpanzees for laboratory use has been an activity selected by people with an alleged Nazi background - speciesism, as it affects chimpanzees, appears psychologically close to racism.

Chimpanzees, gorillas, and orang-utans thrown down a challenge to our conventional morality. They force us to question our ethical foundations. What, then, are these? In my view, morality is about altruism. Many species show basic altruism — the protection of other members of the troop from attack, the grooming of others and, in particular, care for offspring and sharing food with other kin. Human beings show similar behaviour, but it is usually experienced as being motivated either by a (learned) sense of duty or by a spontaneous feeling of empathy based upon the awareness of others' sentiency and, in particular, their capacity to feel pain or distress. Sentiency (consciousness) is, in itself, the greatest mystery of the universe. For 100 years psychologists have fought shy of studying this ultimate phenomenon. Now it is again being examined and its similarities with quantum mechanics have been noted.[3] It is the empathic recognition that others consciously experience the mysteries of pain and distress, much as we do, that often appears to restrain our behaviour towards them.

This feeling of empathy also makes sense in evolutionary terms, and for two reasons: first, it leads to the protection and survival of offspring (and hence our genes), and second, it promotes social co-operation. Sometimes the first of these reasons, the promotion of the survival of our genes, has been emphasised to the point where it is argued that close kinship itself triggers the emotional basis for morality. But, surely, the strength of parental feelings which can exist for adoptive children undermines this argument. Biological kinship is not a necessary condition for protective behaviour, as anyone knows who has seen a cat nurturing a young rabbit or a bitch suckling a kitten. The parental potential is within us all but it can be triggered by, or directed on to, recipients who are of other species. Our kitten Leo will not only lick our old cat Albert, he will also lick me. Nobody taught him to do this. Cleaner fish and ox pecker birds are probably innately programmed to remove parasites from their dangerous but tolerant hosts of other species. Young chimps will play with young baboons. The species do not ignore each other; they interact.

Over the years the circle of morality has gradually expanded to embrace those outside the immediate circle of acquaintance. Foreigners, and those of other religions and races, have slowly been recognised as being similar to ourselves. This is not just an intellectual process but also an emotional one, and the spontaneous feeling of empathy with others appears to expand as familiarity increases. Western human beings are no longer acquainted only with other members of the family and tribe. Increased travel and the advent of television mean that we have become ever more familiar with humans of distant lands and with sentients of other species.

Children at once show sympathy for nonhumans. And they are right to do so. Other primates have been recognised as cousins since modern Europeans first become aware of them in the sixteenth and seventeenth centuries.[4] Indeed, nonhuman primates were, for nearly 300 years, exploited for entertainment in much the same way as were deformed humans, bearded ladies and other human curiosities. Now, in a world where we at least try to show a greater respect for our fellow humans, the time has come for a more general sentientism. What I mean by sentientism is simply that the importance of sentiency should be recognised and that sentiency, in whatever host it arises, should guide our morality. In chimpanzees, gorillas and orang-utans the existence of sentiency seems beyond doubt; indeed, we can be certain that members of these species can suffer just as we can. We are all related through pain. So let kinship and kindness be made one.