DOGS have been "man's best friend" for 30,000 years or more, since the friendliest and most curious wolves began to be adopted as our companions. Flopping in front of the TV last week, I discovered what an appalling cost human friendship has sometimes been for dogs: a significant proportion of our canine pets become severely stressed when they are left at home alone by their owners.

Cameras placed in homes showed anxious dogs pacing to and from the front door, gazing desperately out of the window, howling and yowling like souls in torment. Tests showed the presence of the stress-hormone cortisol. Some of the owners were reduced to tears when they saw the playback.

It is often assumed that we domesticated the dog, but a recent article in National Geographic Daily News suggests that the dogs took the initiative, and adopted us. The wolves that became dogs not only liked us, but became extraordinarily adept at reading our faces and feeling our feelings. So they hitched themselves to our evolutionary wagon, and have been around us ever since.

They have not always been welcomed. Think of Psalm 59, where it is the wicked and violent who "grin like a dog and go about the city". Last week's programme suggested that modern dogs could do with a bit more self-reliance, and suggested how their owners might help them cope with their distressing levels of anxiety.

I am not a dog-owner, but I was moved by the plight of the domestic dog and its need for human company. It made me think about how chancy the path of evolution is, and how its consequences can be happy or disastrous. There is a commonly held view that "nature" is somehow independent of the human species, and that the best we can do for it is to minimise our effects on it. We blame ourselves for the extinction of species, losing sight of fact that although we exploit, we are also exploited, not only by domestic animals but by all sorts of bugs and parasites, funghi and bacteria who find us convenient.

The theologian Matthew Fox sometimes said that everything alive in the universe eats or is eaten by something. This is shocking, but it is also sacramental. We live from others' lives. We give for others' lives. Wolves became dogs because of us. Now we need to save them from losing their dogginess. It is only fair: they give us a quality of faithfulness which we only sometimes give each other.

The Revd Angela Tilby is Diocesan Canon of Christ Church, Oxford, and Continuing Ministerial Development Adviser for the diocese of Oxford.