We seem instinctively to favor other humans over all other animals.

I was raised on a farm around animals, and can be without human companionship for a long time without feeling lonely if I have animals around. But, I have hunted and killed and eaten wild animals, and have killed and helped butcher domesticated animals. I have looked at a fat squirrel in a pecan tree and thought--you'd taste good after I fried you up. I've never had carniverous thoughts about another human being. And I'm not alone. We have now and have had lots of human cultures around the globe, but relatively few cannibalistic ones. We seem naturally to distinguish human from non-human life.

Without reflection, we hold humans to a different standard than we do non-human animals. Even the most fervent vegetarian environmentalist (say a Vegan) does not condemn beavers for building dams across streams, but may condemn humans for building our dams. Logically, the only reason one may condemn a human-built dam as an artificial interference with nature, and admire a beaver dam as an expression of nature, is if humans are placed in a different category than beavers. If a tiger mauls a stage magician, we do not arrest the tiger and try it before a jury of fellow tigers. We unreflectively differentiate the human from the nonhuman.

Even the Jain, the religion that most stresses a prohibition against the taking of any life (the First Great Vow: "I renounce all killing of living beings, whether movable or immovable. Nor shall I myself kill living beings nor cause others to do it, nor consent to it."), has as its majority the Lay-Folk who do not take the Five Great Vows, but instead take 12 lesser vows, which include avoiding directly taking sentient life. But even the Jain privilege humans above other living beings: one cannot attain salvation until one is born human (for some Jain sects, born a man).

The point I am trying to make is that we instinctively differentiate, and give privilege to, human beings as somehow set apart from other living creatures. And we do this in a wide variety of cultures and religions. (more below)

As a Christian, I differentiate and privilege humans above animals on the basis of the doctrine that in humans has been placed the Image of God, and to humans the responsibility to tend and care for creation.

Our modern scientific culture is now blurring the line between the human and the nonhuman. And we are doing this with relatively little public debate. Amazing. We are violating not merely a Christian idea, but an idea that seems to me universally shared: that humans are different and special. Where is the moral debate? Science in and of itself is not capable of asking the "Should we?" question. We need political/ethical/religious debate.

There is much work currently being done around the world, the following articles merely indicate the tip of the iceberg:

human/rabbit

human/rabbit, human/pig, human/mouse