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Irina Marwan (left), filipefrazao (center), Natalia Gdovskaia (right), via Getty Images
The new strain of bird flu has infected more than 90 million chickens and has spread to dairy cows and even humans. Here's what you need to know about the "global pandemic for animals."
Jeff Haynes/Reuters

New research points to a clear origin for humanity’s love of farm-raised chicken eggs. Archaeologists say they’ve found evidence showing that humans in Central Asia began to raise the forebears of modern chickens for their eggs as early as 400 BCE. The reliable supply of eggs also helped the bird become a widely…