Slicing bread, cooking with gas, inventing the wheel — these are the groundbreaking innovations to which we glibly compare many others. But if you want to talk about a real shift (and go a bit old school), you should compare it to the agricultural revolution.
Around 12,000 years ago, our ancestors learned how to grow crops and raise animals for their own consumption, first in the Fertile Crescent, which stretches from North Africa into Asia, then springing up independently among populations all over the world. Farming meant that people could get food more reliably than they did as hunter-gatherers, and on a very basic level, that meant that more humans could survive.
“It’s a tough, rough, harsh, and risky lifestyle being a hunter gatherer,” said Mark Thomas, a professor of evolutionary genetics at University College London. “You’re much more buffered against fluctuations in food supply if you’re farming.” More people and more reliable food allowed people to worry about more than just their basic survival, leading to urbanization, trade, and a faster pace of innovation.
But the downside, Thomas said, was that humans were overall less healthy. Diets were less diverse and more reliant upon starches like wheat and corn, and that had a lot of effects on how humans looked physically.“Early farmers didn’t look healthy because they had shifted to a diet that their metabolism wasn’t optimized for,” Thomas said. “When we shifted to agriculture from a dietary point of view, we made a morbidity-mortality tradeoff—more people were living, but they weren’t living at their optimal health status.”
The negative effects were so pronounced that writer Jared Diamond called the switch to agriculture “the worst mistake in the history of the human race.” With modern medicine and a better understanding of our biology and nutrition, humans today have figured out how reverse some of the detrimental effects that farming has had on our bodies. But some conditions, including autoimmune disorders and decay of our bones and teeth, continue to affect us thousands of years after these changes first appeared in our species. As researchers like Thomas continue to analyze the remnants of early farmers and their genetic information, our understanding of how and why these changes occurred is constantly improving.
Here are some of the changes that happened in human bodies after the agricultural revolution.
1. Farmers had worse teeth than hunter-gatherers
They had food that was easier to eat and more time to eat it at their leisure, so farmers developed smaller jaws than hunter-gatherers. This led to dental issues like malocclusion, or dental crowding, according to a study published earlier this month in the journal PLOS One. Also, farmers ate more starchy and sugary foods, which led to a higher frequency of cavities and tooth decay.
2. Farmers had weaker bones
Researchers still don’t agree on the cause behind farmers’ weaker, thinner bones. Some think it’s because of a shift in diet, others blame a change in the amount of physical activity. Whatever the cause, lighter bones made a lot of sense for our early farming ancestors: “Being robust is nutritionally expensive; if your bones are big it takes a lot of energy to carry that around,” Thomas said. But we still feel the effect today when we break bones or suffer from osteoporosis.
3. Farmers were of smaller stature
Though farmers had more reliable access to food than did hunter-gatherers, their diets were much less diverse and relied more on starches than on meat and vitamin-rich leafy plants. More limited nutrition meant that farmers didn’t grow as tall or as strong as hunter-gatherers. One 2003 study noted that human stature didn’t return to pre-agricultural levels until the end of the 19th century, when we understood what it takes to have a balanced diet.
4. Farmers were more prone to disease
Hunter-gatherers lived spread out across the landscape, moving often as they looked for food. Since they didn’t see other people very often, they rarely passed diseases from one to another; they would only get sick from infections like sepsis or from parasites. But farmers lived closer together, which meant that communicable diseases ran rampant. If farmers didn’t get sick from other people, they got sick from animals; using the first domesticated animals as pets and livestock, humans were living around animals more then ever, unaware of the fact that 70 percent of the world’s communicable diseases come from them.
5. Farmers were milk-drinkers
Today, about one third of the adults in the world have a handy mutation that allows them to drink milk comfortably. Without that mutation, people aren’t able to digest lactase, the sugar in milk, after age five; if they try, they can have severe gastrointestinal discomfort. There are lots of hypotheses for how milk helped early farmers, from staving off disease, or starvation, or dehydration, to aiding fertility. But, just based on the number of people that have the mutation, there’s no question that it helped them survive.
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