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.
The first use of horses in warfare occurred over 5,000 years ago. The earliest evidence of horses ridden in warfare dates from Eurasia between 4000 and 3000 BC. A Sumerian illustration of warfare from 2500 BC depicts some type of equine pulling wagons.