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What’s the News: As human societies adopted agriculture, their people became shorter and less healthy, according to a new review of studies focused on the health impacts of early farming. Societies around the world—in Britain and Bahrain, Thailand and Tennessee—experienced this trend regardless of when they started farming or what stapled crops they farmed, the researchers found.

This finding runs contrary to the idea that a stable source of food makes people grow bigger and healthier. The data suggest, in fact, that poor nutrition, increased disease, and other problems that plagued early farming peoples more than their hunter-gatherer predecessors outweighed any benefits from stability.

How the Heck:

The researchers dug through data from more than 20 studies that collected clues to stature and overall health—everything from dental cavities to bone strength—from ancient skeletons. These studies focused on a wide range of cultures in Africa, Asia, Europe, and the Americas as they transitioned from foragers to farmers.

The team saw that across the board, people’s height decreased and health worsened as they traded hunting and gathering for the garden and the herd.

What accounts for the decline? While we tend to think that growing our food rather than foraging for it must be a good thing, “humans paid a heavy biological cost for agriculture,” anthropologist George Armelagos, one of the researchers, said in a prepared statement.

A diet based on a limited number of crops meant that people weren’t getting as wide a variety of nutrients as when they relied on a range of food sources, leaving them malnourished—and thus, both shorter and more susceptible to disease.

Living in agriculture-based communities likely made infectious diseases more of a problem, as well, the scientists say. Higher population density, disease-carrying domesticated animals, and less-than-ideal sanitation systems all would have helped diseases spread.

This effect was seen over thousands of years, starting at the dawn of agriculture about 10,000 years ago.In more recent times, however, height and health have been increasing, especially in 75 years or so since mechanized agriculture began to spread.

What’s the Context:

Armelagos and his colleague Mark Nathan Cohen first introduced the idea that agriculture could negatively impact human health in a 1984 book, Paleopathology at the Origins of Agriculture. While many researchers were initially skeptical, the idea now has wide support.

This new review bolsters the theory with data from societies across many millennia and five continents, gathered during the quarter century since the book’s publication.

Reference: Amanda Mummert , Emily Esche, Joshua Robinson, & George J. Armelagos. “Stature and robusticity during the agricultural transition: Evidence from the bioarchaeological record.” Economics and Human Biology, July 2011. DOI:10.1016/j.ehb.2011.03.004

Image: Flickr / mckaysavage