Now there are a couple barriers to accepting genetically modified food, and I know that some of you are coming up with the idea of, well, this is not natural. It's not natural to genetically modify, to genetically engineer our food. But I wanna talk about what really is natural? Or actually, what is the myth of natural food? The food we eat comes from plants already extensively modified from their original form. Even heirloom varieties are extensively genetically modified. So let's play a little game. If I give you a choice, what would you prefer to eat? On the one hand, a genetically modified tomato from a major industrial seed producer, you can call that company whatever you want. And on the other hand, a natural wild tomato from the Andes of South America. Which would you choose to eat? Well many of you chose to eat the natural tomato. But really, what's natural? Let's look at these two tomatoes. Two species of tomatoes. One called Solanum pennellii. This is the natural, wild tomato found in the Andes. And the other tomato called solanum lycopersicum, which is the cultivated form of tomato that we have in our salads in the morning. The wild form of tomato, the solanum pennellii, is resistant to diseases, it's resistant to pests. It's a weed. It can grow under any conditions, but it's also very small and unfortunately it's also poisonous. On the other hand, the cultivated tomato is the result of 2,000 years of intervention, 2,000 years of breeding. This has yielded a large, juicy, sweet fruit which is sensitive, but this fruit is sensitive to diseases. The plant is sensitive to pests, it can't survive in the wild. If this would be planted back in the Andes, it would die immediately. But the fruits are delicious. So again, given the choice between the wild tomato and the cultivated tomato, which would you choose? What's natural? We see the same thing with corn. If we look at the wild version of corn, which is called teosinte, and the cultivated corn, we can barely recognize that they're almost the same species. These plants were domesticated over the past 10,000 years in parallel in several regions around the world. Whether it be rice or soybeans in China or India, or wheat, barley, and lentils in the Levant. Or corn and squashes in North and South America. Or cassava in Africa. All of these domesticated plants originated from wild varieties, so what is genetic modification that arose as a consequence of cultivation? Well there's a natural variety in wild plants. For example, if we look at corn in this corn field, there could be corn with large ears and with small ears. Our forefathers selected the plants with larger ears, saved those seeds and planted them. This led to a selection of corn with increasing large ears of corn. And over the generations this led to larger and larger and larger ears of corn plant, plants with corn. We see this actually in archeology. Here we see 7,000 years of domestication of corn from the Tehuacan valley in Mexico. 7,000 years ago the corn that they grew was on a very small cob. This cob got progressively larger until over 500 years ago, the size of the corn was very similar to what we have today in domesticated corn. This resulted through slow selection by the farmers in Mexico. This led to a genetic selection for larger and larger ears of corn. Through this selection, from teosinte, the wild corn to domesticated corn, there were other changes. For example, in the wild corn, the kernels are surrounded by a hard casing. This hard casing actually protects the seed, so that it can be spread by animals. But to get to the corn, to eat it, you have to break it open. The original farmer, 7, 8,000 years ago selected for varieties that no longer had this casing. We no longer see this casing on cobs of corn. But again, if you would take this domesticated corn, even domesticated corn 5,000 years ago that had lost the casing. It could not survive without human input. Why? Because the cobs would fall on the ground, and the seeds could no longer be dispersed cuz they didn't have their casing. So over 7,000 years of cultivation, there was a decrease in branching, an increase in seed size, were also selected for. Which led from that very thin teosinte cob to the modern corn that we all enjoy today. The take home message here, is that human intervention has.invented all, now I repeat that, human intervention has invented all of our cultivated foods. This is also clearly seen in Brassica. Let's take for example a wild mustard, which is very similar to the Arabidopsis plants we saw in some of our earlier lectures. The difference between wild mustard, and cabbage, and broccoli, and califlour, and brussel sprouts, and kale is very, very small. Genetically, these plants are essentially identical. Changes in a very small number of genes can cause a huge change in morphology. And thus give us the vast diversity of Brassica vegetables. And then over the past 200 years, the science of Gregor Mendel and Charles Darwin, has paved a way for scientific plant breeding.
