All breeds of dogs are some convergence of evolutionary factors and breeding. Some breeds are more "man made" than "nature made," i.e., there is little influence on their form and function from the forces of natural selection. For example, the bulldog breed was bred 'backwards' to create a longer-legged, more energetic version of the original breed. The Tibetan breeds, the Lhasa Apso, the Tibetan terrier, on the other hand, is more a product of evolutionary rather than human forces and factors. Of the five recognized Tibetan breeds, the Tibetan Terrier, Lhasa Apso, Tibetan Spaniel, Do-Khyi (Tibetan Mastiff), and the Shih Tzu, the Lhasa Apso is unarguably most strongly influenced by the harsh, demanding Himalayan Tibetan climate.

There are several reasons for this. First, the Tibetans only started to selectively breed the Lhasa Apso eight hundred years ago in the in the sacred city of Lhasa, Tibet's traditional capital and home of the Dalai Lamas. The breed originated, however, over two thousand years ago in wider the Tibetan environment.

Second, historians and breeders doubt that these Tibetans did the sophisticated selective breeding than we do today. The early Tibetans were hunters and herders depending on the native characteristics of the Tibetan breeds to hunt, guard flocks, and to serve as companions and guards inside tents. The natural characteristics of the Tibetan breeds, fashioned by the forces of evolution, were more than sufficient for the demanding survival tasks the Tibetans faced.

Third, the physical form of the Lhasa Apso has clearly remained unchanged from the original form because it is still exceptionally well designed to conserve heat. Cold adapted animals have bodies with a higher ratio of muscle and fat mass to bone mass than closely related breeds that adapted in warmer climates.

Additionally, the amount of heat produced by an animal is known to be proportional to its mass or volume -- the larger you are, the more heat you produce. We know, however, that heat loss is proportional to the body's surface area -- the more surface area you have, the faster you lose heat to the environment. Heat conservation is a function of the ratio of body mass to surface area: take two animals that have the same mass, but let one have less surface area then the other, the one with more surface area will loss heat faster. Because the Lhasa Apso is short and round, it has less surface area than its longer-legged, equally weighted, warmer climate counterpart. Those same evolutionary forces also govern our body types: Eskimo peoples have short and stout bodies and less surface area than equally weighted Equatorial peoples who have long lean bodies and high surface area. In short, to limit heat loss in the cold, an animal's body should be as compact as possible and the extremities as short as possible

Finally, nature has adapted the Lhasa Apso's body is to the hills and villages of the Himalayan highlands: they are built for stamina -- not speed; for walking, climbing and jumping -- not trotting and running as are plain animals.

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