The Los Angeles Times reports new evidence of non-human primates' understanding of life and death: "Some chimpanzees seem to grieve similarly to humans in the face of a fellow chimp's death, two new studies have found, appearing to comfort the dying, experience trauma after death and have trouble letting go."

The research is also described by the Scientific American Web site. Of course this isn't the first news of animal grief. There's Bongo Marie, the heroine of the title anecdote of Eugene Linden's The Parrot's Lament, for example. And there are African elephants who seem to explore the mysteries of the fate of departed family members in books like Cynthia Moss's Elephant Memories.

In discussions of animal intelligence, researchers and philosophers sometimes sort themselves out into those who believe that people are not as far as they think from other animals, and those (some but not all of them religious believers) who may acknowledge this but are more interested in the bright lines that make us different. An outstanding member of the former camp -- who still acknowledges a qualitative gap -- is the Dutch-born primatologist Frans de Waal, interviewed by The New York Times Freakonomics blog:

Q: Can an animal be "immoral" or are they "amoral"?

A: That's a BIG question, which I can't answer in a brief note. An organism can only be immoral if it is part, and adheres to, an agreed-upon system of morality, as we do. I don't believe that chimpanzees, or other nonhuman animals, are moral beings in the sense that we are.

But to call them amoral isn't correct either. Amoral means a total absence of morality, and it is obvious that the building blocks of morality (empathy, sympathy, cooperation, social rules) can be found in animals other than us.

Grief may well be one of these proto-moral blocks. But can it extend to consciousness of one's own mortality? The Oxford mathematician Marcus du Sautoy cites the mirror-recognition research of Gordon Gallup, who first showed elegantly -- by surreptitiously applying a temporary red dot to the forehead and observing the reaction -- that only a few species realize they are seeing themselves in a mirror (even brainy parrots chatter with a perceived playmate) rather than another creature:

It is striking that chimpanzees start to fail the test once they reach 30 years old despite having some 10 or 15 years left to live.

The reason is that self-awareness comes at a cost.

Consciousness allows the brain to take part in mental time travel.

You can think of yourself in the past and even project yourself into the future.

And that is why Gallup believes that in later life chimpanzees prefer to lose their ability to conceive of themselves.

"The price you pay for being aware of your own existence is having to confront the inevitability of your own individual demise.

"Death awareness is the price we pay for self awareness."

So while exploring our kinship with other animals has generally promoted respect and improved treatment, perhaps non-humans themselves benefit from the bright line's existence. Dissolving it might even be monstrous, as this satirical Onion video suggests.