According to research published in Proceedings of the National Academy of Sciences, humans are eating more meat overall due to growing economies in China, India and elsewhere. Researchers concluded that humans' global medium tropic level--a metric used in ecology to determine a species' place on the food chain--has increased by 3 percent, or .006, over the past 50 years.

“It seems like a small difference, but when you think about how it’s calculated, it’s big,” says Thomas Kastner, an environmental scientist at Alpen-Adria University in Vienna who was not involved in the study, speaking to Nature News. “A change by 0.1 means you are eating considerably more meat or animal-based foods,” says Kastner.

Trophic level increases were not globally uniform. Growing economies in India and China have meant marked increases in tropic level, while tropic levels have declined in places like Iceland and Mauritania, where diets that once consisted mainly of fish or meat have diversified.