A Type D personality is distressed, Type D's have a negative outlook towards life and are pessimistic. A small event that is not even noticed by type B can ruin type D's day. Type D personalities are more subject to depression than other personality types.
For most of human history, horses were seen as prey to be hunted for sustenance. During the late Pleistocene, around 55,000 years ago, Neanderthals scavenged off of horse carcasses and made occasional kills of their own.
Horses taken from the Spanish were well-established in the nomadic hunting cultures by the early 1700s, and indigenous groups once living east of the Great Plains moved west to hunt the larger bison population.