Grazing animals , including horses , were nearly wiped out in the Hemphillian event , about five million years ago. Horses declined to a single species, which appears so sporadically in the fossil record as to suggest that for a time it teetered on the brink of oblivion. Imagine human history without horses.Bill Bryson A Short History of Nearly Everything
Horses may have been domesticated and used for meat and milk earlier but the first evidence of horse used for riding and transport comes in 4000 BCE. Humans could cover vast areas of land and move themselves and their goods by using horses. If humans had remained travelling about on their own two feet both settlements and economies would have been vastly different. Horses were seen as symbols of power by ancient civilizations and can be seen in cave drawings dating back tens of thousands of years. If we did not have horses it could be argued that we would still not have reached the era of globalization!
What else would we have missed?
The Great Wall of China. This wall was built to keep out marauding Mongolian warriors who were mounted on horses. Without the horses they would not have attacked and the wall would not have been necessary.
The Roman Empire. The Romans travelled by ship to extend their Empire but they also travelled by horse to the four corners of the known world as well. Also, without horses there could not have been the Equestrian Class. This class ranked below the Senatorial class in Rome. and was the second of the property based classes.
The great battles The cavalry was a critical part of war in human history. If there had been no cavalry would there have been the kinds of battles that shaped human history?
Horses in History outside Europe. How would Queen Rani have escaped the British armed forces in Jhansi at the start of the Indian Rebellion in 1857 if she did not have her horse Baadal and with her young son strapped to her back she leapt to freedom.
The history of North America. The indigenous peoples of North America became skilled horsemen. How would their history have been different if they never had horses?
Horse Sport. Medieval knights would not have been jousting.
There would not have been chariot races in ancient Rome, or horses taking part in the first Olympics in Greece. And now no horse racing, no jumping, no dressage, and so on it goes.
The work horses. We now have huge machines to do the work in the fields sowing and harvesting but in earlier times the work horse brought us to a new level. Imagine if we had never had horses and agriculture was just a human endeavor?
There is no doubt in my mind that if horses had become extinct in the Hemphillian event the history humans would be entirely different. The domestication of horses was as significant in human history as the invention of gunpowder, the harnessing of electricity or the arrival of the internet.