Although English life was beginning to change with the gradual development of cities, the economy was still mostly agrarian in the 1200s, with 90 % of the population (estimated to be around four million people in 1300 AD) making their living off the land, either
as farmers (
growing wheat for personal use or other grain crops to feed livestock) or
herders (mostly sheep and goats).
The same ancestral autosomal recessive mutation for the progressive rod cone degeneration (prcd) form of progressive retinal atrophy (PRA) is found in the American Cocker Spaniel, American Eskimo Dog, Australian Cattle Dog, Australian Shepherd, Chesapeake Bay Retriever, Chinese Crested Dog, English Cocker Spaniel, Entelbucher Mountain Dog, Finnish Lapphund, Golden Retriever, Kuvasz, Labrador Retriever, Lapponian
Herder, Norwegian Elkhound, Nova Scotia Duck Trolling Retriever, Poodle, Portuguese Water Dog, Silky Terrier, Spanish Water Dog, Stumpy Tail Cattle Dog Swedish Lapphund, and Yorkshire Terrier.3 This list continues to
grow as more breeds are discovered with the same defective gene.