OFFICIAL44 What is the lecture mainly about?

[00:00.00]NARRATOR: Listen to part of a lecture in an anthropology class.
[00:04.43]FEMALE PROFESSOR: So, we've been talking about early civilizations—how they developed … and early agriculture—[00:11.70]and it’s believed that agriculture arose independently in a few areas of the world about 10,000 years ago, and then spread from those areas to the rest of the world. [00:22.57]Those cradles of agriculture include the Middle East, China and Southeast Asia, and parts of the Americas.
[00:30.64]Now, for many years archaeologists have speculated that agriculture also arose independently in another center, too—New Guinea, which is just north of Australia, in the South Pacific Ocean.[00:44.17] You can see it on this map.
[00:46.70]So … it'd been assumed for a long time that New Guinea … that domesticated plants and animals—the practice of agriculture generally—had been introduced from Southeast Asia about 3,500 years ago—had come south, essentially.
[01:05.00]Then, in the nineteen sixties and seventies, research was conducted at sites in New Guinea to explore the possibility of independent agricultural development—[01:15.43]but unfortunately the evidence gathered at that time was inconclusive.
[01:20.02]For instance, although evidence was found of deforestation—you know, cutting down trees—from at least 7,000 years ago—that is, long before we had thought previously—[01:32.01]it was unclear whether the forest had been cleared by farmers to plant fields or by hunter-gatherers so they could hunt more easily. [01:42.25]And many plant remains, like seeds and fruits, don’t preserve well in swampy soils, in humid environments like you often find in New Guinea, [01:51.36]so really, the proof was limited.
[01:53.63]But, recent research has turned up some pretty convincing support. [01:58.91]A group of archaeologists returned to a site that had been previously examined—Kuk Swamp, which is in a mountain valley in the highlands of what is now Papua New Guinea.
[02:10.08]Based on their findings, they identified a succession of phases of agricultural development in the wetlands there, with several of these phases predating the earliest known agricultural influence from Southeast Asia.
[02:27.51]At the site in Kuk, they used an array of modern archaeological methods to analyze sediment samples from the soil. [02:35.00]From the oldest soil layer, dating back 10,000 years, they found evidence of pits, stake holes, and ditches. [02:45.01]Now, these all indicate that crops were being planted … [02:49.25]plants are tied to stakes and ditches are … for, for drainage—eh, proof of a very early first phase of agricultural development.
[02:59.33]The second phase, which they identified from a higher layer of soil, featured regularly distributed mounds. [03:07.46]Mounds were constructed to plant crops that can’t tolerate very wet soil, such as bananas, because remember, Kuk is a swampy wetland, and bananas wouldn’t ordinarily grow well there … .
[03:20.44]And, in the layer from Kuk’s third phase, they found evidence of an extensive network of ditches and drainage channels—indicating a further refinement of wetland cultivation. [03:34.60]Because they had more advanced techniques than were available to earlier researchers, the archaeologists also were able to identify actual plant remains, microfossils, in the soil—from banana plants—and … and also grains of starch from taro on the edges of stone tools that date from about 10,000 years ago.
[03:56.90]Finding the taro remains was very important, because it meant that it must have been planted there—brought from the lowlands, because taro doesn't grow naturally in the highlands.
[04:08.27]And as for the bananas, researchers also found a high percentage of fossils from banana plants in sediment samples dating from about 7,000 years ago—proof that bananas were deliberately planted. Because where bananas grow naturally, the concentration of the plant fossils is lower—[04:29.90]bananas don't naturally grow so densely. [04:32.63]As a matter of fact, recent genetic research—genetic comparisons of banana species—suggest that the type of banana grown in New Guinea was domesticated there and then brought to Southeast Asia.
[04:47.14]So, not sure where I'm going with this?
[04:50.08]Well, usually we expect to see that certain social changes are brought about by the development of agriculture—structural changes in the society, like rapid population growth, different social classes … [05:04.81]but, New Guinea, it's largely unchanged … [05:08.81]it's remained an egalitarian and rural society, so what does that tell us about the usual assumption?