Lecture: One of the biggest cultural shiftsAuthor: QQ-464094252: Narrator: Listen to part of a lecture in an Archeology Class. Lecturer: One of the biggest cultural shifts in human history was the shift from food gathering cultures to food producing ones. Agriculture was revolutionary because of the lifestyle changes it brought about, and the key factor in this transformation was the domestication of plants. Now ~ what do we mean by plant domestication? Jonathan? Jonathan: It's uh- when you plant and harvest crops yourself. Rather than just picking what's growing wild. Professor: Oh- kay but um, well, let's tease this apart a bit. When you plant your own seeds, work the land, that's what we call, cultivation. And that's the first step towards domestication. Domestication involves the actual genetic modification of wild plants so they're more beneficial to people. Easier to harvest for example. These phases evolve in the plants because of cultivation. Um take wheat for instants. Wheat spikelets are attached to the stalk and carry the seeds or grain, which people grind into flour. And in naturally growing wild wheat, the spikelets fall off the stalk onto the ground over time. Okay, so you can gather those spikelets after they've fallen, then grind up the seeds, right? Well, that's fine, if you have a nomadic lifestyle, and can be in the right place at the right time. But if you live a more settled lifestyle, you might want to control things a bit. You'd prefer type of foods where the spikelets stay on the stalk until you decide to harvest all that wheat at once. Well, for that to happen, the wild plant has to undergo physical changes, so the spikelets don't scatter easily. And that's where cultivation comes in, because once people start growing plants deliberately, they select ones with certain traits, like spikelets that stay attached longer. And when human cultivation results in genetically changed plants, that's when they can say those plants have been domesticated. Female Student: But how long does it take to domesticate plants, and how long do they need to cultivate it? Professor: Good question, up until recently, we thought it happened relatively quickly. In fact, in 1990, two researchers made a computer model using data from cultivation experiments, and found domestication could occur within 200 years or less. So the consensus among most archeologists was that agriculture appeared rather abruptly, that crops were domesticated shortly after people began cultivating fields um, about thirteen thousand years ago. But more recent data has shown that these assumptions are questionable. In one study, researchers look at wheat spikelets dating from 10,500 years ago from a site in Turkey. They examined them under a microscope. And uh, on the lower end of some of them, where the spikelet attaches to the stalk, the edge wasn't smooth it was jagged. Now, what do you think that means? Female Student: They were broken off the stalk? Professor: Exactly. They didn't come off easily. They needed human help and that's a sign of domesticated wheat, and this is the earliest evidence of domesticated wheat that we have. But the researchers also found spikelets with smooth round edges. Those were some wild wheat. So wild and domesticated wheat plants were growing together in the earliest cultivated field. and the researches concluded that bold domestication might have taken longer than previously thought. That wild plants were replaced only gradually by domesticated plants whence cultivation had begun. Jonathan: So, when did people start to cultivate wildly? Was it when they realized they could use it to make flour? Professor: Well, that's another of a long-held assumption. But guess what? At a site in the Middle East, evidence was found that the people living there 23,000 years ago were grinding wild seed in barley to make flour, but there was no evidence whatsoever that they were cultivating plants. Now, that was during the last ice age, which shows that humans were using wild plants for thousands of years before they switched to cultivation. Jonathan: Do we know what made them switch? Professor: There are different hypotheses. One is, that the rise of farming has to do with climate changes that occurred when the last glacial period ended. A milder more stable climate could have triggered the rise of farming, but many archeologists think that this can't be the sole explanation, that other factors might have played a role. Like, uh, social changes as hunter-gatherer community became more sedentary. What makes it so difficult to answer your question is the fact that we're looking for a global explanation for agriculture. You see, contrary to an older view that agriculture started out in just two places, the Middle East and the Americas, archaeologists now agree that domestication of plants took place independently in many different parts of the world.