I've read in several places (Jared Diamond, for one) that in pre-modern civilizations, animal breeders did not purposefully breed animals with traits favored by the breeder, that such artificial selection happened unconsciously.  While I accept that noone may have been attempting long-term breeding programs, it seems pretty clear that traits are inherited, and breeders would consciously choose their best animals for that reason.  I suspect the same may have been true for plants.

What do you think?

Hi Brian,

It would not be necessary for the breeders to know that traits are inherited. By spurning animals or plants that did not meet whatever requirements they were after they would still be imposing selection.

Dogs are perhaps a good example as they have a long history of domestication by humans. Many breeds now kept as pets are a lot more docile than their wild counterparts, but one can imagine a dog prone to attacking humans would be driven out or killed by our ancestors. Thus, these animals would have a far lower chance of passing on their genes.

Conversely, dogs that were submissive and did what we wanted would be favoured, both in being protected from predators and fed or watered.

So selection does not have to be conscious even if it is 'artificial.' As long as the character(s) under selection are inherited then evolution can occur.