While the functional elements of MEMS are miniaturized structures, sensors, actuators, and microelectronics, the most notable (and perhaps most interesting) elements are the microsensors and microactuators.
The horse (Equus caballus) has made many dramatic and significant journeys. During the Pleistocene (Ice Age), more than 20,000 years ago, wild horses that had evolved in America migrated to the Old World, Eurasia and Africa. More than 6,000 year ago in the Volga basin of eastern Europe horses were domesticated and in the subsequent millennia spread to other parts of Asia, Europe, and Africa.
A number of hypotheses exist on many of the key issues regarding the domestication of the horse. Although horses appeared in Paleolithic cave art as early as 30,000 BCE, these were wild horses and were probably hunted for meat. How and when horses became domesticated is disputed. The clearest evidence of early use of the horse as a means of transport is from chariot burials dated c. 2000 BCE.