Not Your Grandma's Bird: Turkeys Have Doubled in Size Over Past 70 Years

Domesticated turkeys are much different than their ancestors.

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The turkey you put on your plate this Thanksgiving is much different — and larger — than ones eaten in the 1800s (no, the Pilgrims didn't eat turkey), according to a new study by researchers at the Smithsonian Institution.

"Ancient turkeys weren't your Butterball," says Rob Fleischer, of the Smithsonian's Conservation Biology Institute. "On average, the domestic turkey has doubled in size over the last 70 years."

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Domestic turkeys aren't even all that similar to today's wild turkeys: They've been selectively bred so much that they are now genetically different, he says.

"They're at least as different, if not more so, than different dog breeds," he says. "They're not different species, but they're different."

Fleischer and his team are still trying to determine the exact function of the differing genes, but in chickens, similar genes contribute to the size and speed of growth of the bird.

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Of the estimated 45 million turkeys Americans eat every Thanksgiving, the Smithsonian notes that the vast majority of them are descendants of Mexican turkeys, where scientists believe they were first domesticated by natives more than 2,000 years ago. According to the U.S. Department of Agriculture, the average domestic turkey is about 29 pounds today, compared to 13 pounds in 1929.

Modern domesticated turkeys have even less in common with those ancestors than they do with modern wild turkeys. Today's Thanksgiving turkeys are more susceptible to infectious disease because they lack genetic diversity, Fleischer says.

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But the discovery could also give breeders the chance to reintroduce some desirable characteristics from wild turkeys back into the domestic stock.

"If there are specific traits we like in wild turkeys that aren't in domestic turkeys, we can breed them with the wild stock," Fleischer says. The team hasn't yet been able to analyze what the differing genes control, but genes that encourage breast growth or increased activity levels could lead to a better tasting, larger bird. "We've found whole regions of chromosomes that are different," he adds.

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Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at