This one is about man’s best friend. Who, as it turns out, is also man’s oldest friend.

No one knows for sure when civilization first started. Scientists guess that the domestication of plants and animals first happened in the fertile crescent of the Middle East. We can say with some certainty that “prey” animals – such as sheep, goats, and cattle – were domesticated around 10,000 years ago. Next, the domestication of “commensal” animals that live among us and feed off our scraps – such as chickens and pigs – occurred around 8,000 years ago. Finally, “draft” animals that we keep for working purposes – such as horses, camels and oxen – came into the mix around 5,000 years ago.

(Side note: Cats apparently domesticated themselves around 8,000 years ago, when they started hanging around early human villages in search of rodents. But in all the time since, we haven’t really seen any value in domestic cats…)

However, all of these domestic beasts are newbies compared to the family dog. Scientists have previously discovered a canine jawbone with the DNA of a modern dog, buried among human remains, in a cave in Germany, that dates to 14,700 years ago.

And just this week, a new Stony Brook University study that compared modern dog DNA to that within several ancient dog fossils offers a startling conclusion: dogs were apparently domesticated, in Europe, by human hunter-gatherers between 20,000 and 40,000 years ago.

These first dogs were descendants of a sort of proto-wolf (from which today’s grey wolf is also descended, making modern dogs and wolves cousins, but not descendants, of each other). They had features consistent with today’s dogs, such as floppy ears and skulls smaller than wolves. But they were probably only semi-dependent, living around humans part of the time but hunting for themselves as well. They did not have the ability to digest starch, so they could only eat the protein part of the human diet.

And there’s more. The new study also suggests that ALL dogs on the planet are descended from this single dog population. It appears one branch of these dogs headed west and spread across Asia all the way to China, while a second branch went south to the Mediterranean, and onwards to Africa, the Middle East, and South Asia.

All of which proves, of course, that for as long as we have been modern humans, everywhere around the world, there’s only one animal who has been with us every step of the way. Walking alongside us, hunting for our dinner, carrying our bags, pulling our gear, guarding our families, licking our face.

(Oh, and chasing those pesky cats out of the house.)

Good boy.