Milloin eri koirarotuja on aloitettu jalostamaan?
In 2017, a study showed that 9,000 years ago the domestic dog was present at what is now Zhokhov Island, arctic north-eastern Siberia, which was connected to the mainland at that time. The dogs were selectively bred as either sled dogs or as hunting dogs, which implies that a sled dog standard and a hunting dog standard existed at that time. The optimal maximum size for a sled dog is based on thermo-regulation, and the ancient sled dogs were between . The same standard has been found in the remains of sled dogs from this region 2,000 ago and in the modern Siberian Husky breed standard. Other dogs were more massive at and appear to be dogs that had been crossed with wolves and used for polar-bear hunting. At death, the heads of the dogs had been carefully separated from their bodies by humans, probably for ceremonial reasons.
9,000 years ago