Lecture 43 - Excerpt

Listen again to part of the lecture, then answer the question

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 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 does the professor say this thus the plot thickens?