A lecture from a social science class (2)
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Prof: Several theories compete to explain when, how, and where -- check that, why -- wild horses were initially domesticated. Primitive cave art depicts horses as early as 32,000 years ago, but it's generally agreed that humans did not domesticate the animals until sometime between 5,000 and, uh, 2,000 BC. Many scholars accept a theory, er, an hypothesis, that domestication occurred in the Ukraine about 4,000 BC. However, recent archaeological evidence indicates that horses in northern Kazakhstan might have been domesticated as much as 1,600 years earlier than that by people of the Botai culture. The Botai appeared to depend on horses for transportation, food and tools. But ... [pause] one of the archaeologists who discovered this new evidence has speculated that horses were domesticated even earlier, probably in Russia or the Ukraine, and then ridden east to Kazakhstan. Thus the plot thickens.
Why is it so hard to pinpoint the definitive time and place of the earliest horse domestication? One, a major reason is a lack of concrete evidence, such as bits, reins, spurs, and saddles. Anatomically, modern horses are almost identical to their wild ancestors, which forces researchers to rely on circumstantial evidence in formulating domestication hypotheses. Archaeological excavations at several eastern European sites that date to the 4,500 to 3,000 BC range, for instance, reveal equine molar wear likely caused by friction from a bit. Whether the use of a bit signals full domestication or simple captivity, however, is subject to debate. Um, at the Kazakhstan site mentioned above, part of the case presented for domestication is soil analysis that indicates ancient, uh, horse manure within a corral-like enclosure.
But again, the fact horses may have lived, er, been kept together in a corral does not necessarily equate with domesticity, because many ancient peoples used horses for meat and, uh, help with labor, similar to the use of oxen in harvesting today. Recent DNA comparisons between living horses and horse fossils suggest that domestication cannot be narrowed to a single place or time; rather, it occurred more or less simultaneously all over the world. Because the DNA analysis revealed widespread genetic [false start] widespread genetic variances among both modern and ancient horses - unlike other domesticated animals, like sheep and cattle - it appears that domesticated horses had multiple wild lineages in many different places.
One prominent theory holds that there were four distinct horse prototypes, which may or may not have been different species, and that these prototypes were domesticated at differing times and places as they adapted to various environments. The first of these is the "draft" horse, a small, thick-skinned Shetland pony ancestor that developed in the cold, wet climes of norther --northwest -- Europe. A second prototype is the Tarpan, from cold and dry north Eurasia. The Tarpan is a pony-sized, dun-colored creature that preceded today's Przewalski's Horse - which is the only equine that has never been domesticated. The third prototype, which developed in, um, central Asia, was dubbed "warm-blooded" or "forest horse." This long-necked, narrow-headed equine was larger than drafts and Tarpans, and the forefather of heavy horses like the Andalusian. "Oriental" horses, the fourth subspecies, were slimmer, beautiful, fine-boned animals that adapted to the dry, hot climate of western Asia, and were probable progenitors of modern Arabian horses.
To a large extent, the domestication of horses depends on one's definition of the verb domesticate. Ahem. While it is clear from the, uh, archaeological evidence that the earliest role horses played in human history was as a source of food, and that pictorial and written depictions make it unequivocally clear that horses had been trained to pull chariots and use in warfare by about 2000 BC, the, uh, process of transition between these two polarities remains murky. One group of theorists believes that horses cannot be classified as domesticated until there is evidence that they have bred in captivity. A leading proponent of this viewpoint, researcher Marsha Levine, has hypothesized that horses were domesticated gradually, most likely by humans raising the foals of adults slaughtered for food. According to Ms. Levine, over time the hand-raised horses became pets, and rather than eating them, people learned how to ride them and harness their speed and strength in order to capture other food sources, such as bison and deer. They also bred these horses with each other, though the exact date of the first successful domestic mating, like most of the evidence surrounding horse domestication, remains unclear.
What is the lecture mainly about?
Why does the professor say this: "Thus the plot thickens"?
According to the professor, what is the main obstacle to determining the origin of horse domestication?
What does DNA analysis reveal about the domestication of horses?
Why does the professor mention researcher Marsha Levine?
All of the following are mentioned in the lecture as prototypes of modern horses EXCEPT