People have been gardeners for thousands of years. In that time we have modified plants to meet our needs, whether that be good storage, easy harvest, or ripening at the same time. It’s usually a win/win, we get food, the plants get looked after. However some of the changes have been so drastic the plants can no longer survive without us.
- Corn is a grass, it comes from a wild grass called Teosinte. Over thousands of years the Mesoamericans selected those plants that grew multiple rows of seeds, until they produced giant cobs. The same amount of work cultivating gets you far more food to eat. And now corn cannot grow on its own because the cobs do not naturally release the seeds, they need farmers to do that for them. There have been similar but less extreme changes in all the major grains.
- Cabbage and
- Broccoli are all members of the same species, Brassica oleracea along with brussel sprouts, kale and a few others. The original species was a useful wild cabbage, and farmers began emphasising and keeping different characters. Cabbage and the similar ones emphasised the leaves, cauliflower is the beginning of the flower stalk that doesn’t develop properly, and broccoli is a very short flower stalk.
- What colour are carrots? They used to be purple. They were domesticated on the Iranian plateau around 5000 years ago and gradually spread westward. The purple colour is caused by anthocyanins, the same chemicals that give most of the red and purple colours in plants and seems to be protective. At some point there was a mutation that stopped anthocyanin production and caused yellow carrots, and a further mutation led to white carrots. There’s very little evidence for what was happening, but somewhere around the 16th century growers in Holland hybridised several variants and produced orange carrots with high levels of beta carotene.
- Following the theme, wild Pineapples were small and seedy until early farmers encouraged them to become larger and juicier. A modern pineapple is actually many berries stuck together and commercially they are not fertilised, so they usually do not produce seeds. They are naturally pollinated by hummingbirds.
- Nectarines are mutant peaches that appeared one day with smooth skin.
- Bananas are herbaceous berries that were probably first domesticated in Papua New Guinea 7 – 10 000 years ago. Once again, the wild variety are filled with large, hard seeds and farmers have selected the best ones for eating until they only have tiny vestigial seeds. Commercial bananas are produced from offshoots.
- Zucchini and
- Pumpkin are also the same species, Cucurbita pepo. Actually it’s a bit more complicated because ‘pumpkin’ includes many different species, but it does include C. pepo. Zucchini are picked while still immature, which is why the seeds are so soft. Like corn, p0tatoes, pineapples and tomatoes they come from South and Central America.
- Artichokes are actually thistles, the part we eat is the flower bud and the choke inside is the immature petals. The vegetable was probably originally grown for its leaves, but larger buds were also encouraged and developed into what we have today.
- Potatoes are members of the deadly nightshade family, and the originals were quite poisonous. The green parts are still very poisonous and should not be eaten. In spite of the huge number of varieties they seem to be a single species and probably only developed once, but it was almost certainly through hybridisation of several weedy wild species.
- And how could this list be complete without mentioning genetically modified plants? While this is far too short to get into the whole debate, it has to be said that a lot of the hysteria about GMOs is just that – hysteria whipped up by talk of ‘frankenfoods’ or religious thinking. The idea that we shouldn’t add genes to a species is way too late – we’ve been doing it for a very long time. When two banana species or several potato species were crossed thousands of years it was introducing genes that would not have been in that plant naturally.
There are definitely problems to be aware of – are you introducing an allergen? will a pesticide resistant strain escape into the wild and become a pest? But they are similar to problems faced by traditional plant modification. There are also ethical problems with companies forcing farmers to be dependent on them for seed, but that’s a business problem not inherent in genetic modification. Just like any other type of agricultural development, each new plant or system needs to be judged on its own merits, not dismissed because it was made in a particular way. Two lovely examples of genetic modification include golden rice, which was engineered to produce beta carotene to help with Vitamin A deficiencies in poor countries, or some of the salt resistant crops being developed in India. With climate change causing increased storms bringing salty water further inland in India, salt resistant crops are more and more important to feeding their growing population.
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