Mystery of Plant and Animal Domestication Deepens: How Humans Tamed the Wild

Thousands of years ago, our ancient ancestors domesticated plants and animals for their own use. Now, though, researchers have shown that we may know far less about this process than we might at first have thought. The new findings reveal a gap in our knowledge, and may lend insight into our ancient past.

About 12,000 years ago, humans began planet and animal domestication. Yet out of the roughly 200,000 species of wild flowering plants available, people only domesticated a mere dozen. In addition, out of the 148 species of large, wild mammalian herbivores and omnivores, humans only domesticated about five.

So why did humans domesticate so few plants and animals? That's a good question, and it reveals something about humans in general; the tiny percentage of domesticates shows that there are limitations to human agency.

"The big focus right now is how much unintentional change people were causing environmentally that resulted in natural selection altering both plants and animals," said Fiona Marshall, one of the researchers, in a news release. "We used to think cats and dogs were real outliers in the animal domestication process because they were attracted to human settlements for food and in some sense domesticated themselves. But new research is showing that other domesticated animals may be more like cats and dogs than we thought."

Even today, African pastoralists can only afford to kill a few of their cows, or they risk the entire herd. This means that artificial selection was probably very weak. Instead, it's possible that the environment had a larger role to play.

"The comparable idea for plants is the dump heap hypothesis, originally proposed by Edgar Anderson, a botany professor here at Washington University," said Kenneth Olsen, one of the researchers, in a news release. "The idea is that when people threw out the refuse of plant foods, including seeds, some grew and again set seed, and in this way people inadvertently selected species they were eating that also did well in the disturbed and nutrient-rich environment of the dump heat."

These latest studies show that while there are several theories to domestication, it may not be as simple as humans selecting desirable traits. Instead, it's very likely that chance and environmental conditions played an even larger role. This, in turn, shows us a bit more about our history.

The findings are published in two different studies here and here in the Proceedings of the National Academy of Sciences.