No matter what football fans may say, when the Super Bowl takes place on Sunday in Atlanta, the New England Patriots and the Los Angeles Rams will not be be tossing around a pigskin. After all, the ball used in football is made of cow hide — steer hide, to be precise.

But there is some truth to that idiom. The first footballs used by American college players were once made out of a pig body part.

When Americans were just starting to play an early version of the sport in the 1850s, the ball they used was the air-filled bladder of a pig, which has been likened to a deflated balloon and is extremely elastic, according to Newton’s Football: The Science Behind America’s Game by Allen St. John and Ainissa G. Ramirez. The first players inflated the bladder by mouth, stuffed it in a leather covering, and then they stitched the leather back together over the bladder. But it quickly became clear that these early footballs were not very durable. Whenever they leaked or got a hole, they’d be stuffed with some material like straw.

The football that Americans play evolved from rugby, which evolved from soccer, and closely resembled both sports in its early days. In fact, during the first recorded college football game, on Nov. 6, 1869, Rutgers University and the College of New Jersey (now Princeton University) played a game that used a round rubber ball. Then, five years later, an oval leather ball, resembling the kind used in rugby, featured in the Harvard-McGill game on Oct. 23, 1874, in Cambridge, Mass. In the 1860s and 1870s, once Richard Lindon developed a rubber version of the pig bladder for rugby players — basically a frame underneath the leather encasing that kept the ball’s firm, oval shape — and a pump to inflate it, then American football players started to use the same to maintain the shape of their footballs.

But as the rules of the U.S. sport changed, the design of the ball changed too.

After the forward pass started being used in 1906, the shape of the ball kept getting gradually narrower, becoming what’s officially called a prolate spheroid. That shape both “honored the ball’s porcine roots,” as Newton’s Football put it, and more importantly, made it easier to cradle and tuck under the nook of the arm. (The first completed forward pass in a professional game took place on Oct. 27, 1906, in an Ohio League game, when George “Peggy” Parratt of Massillon threw to Dan “Bullet” Riley of Benwood-Moundsville.)

“In those early days, it was a running and kicking game, strong emphasis on kicking,” says Jon Kendle, archivist of the Pro Football Hall of Fame in Canton, Ohio, where the National Football League was founded in 1920. The narrower design is “due to the forward pass being more and more utilized and needing to streamline the football to make it easier to throw, catch, and hold.”

The reason the game started to be more focused on passing had to do with concerns that football had become too dangerous.

“The whole purpose of legalizing passing was to make the game less violent,” says Michael Oriard, author of several books on the history of football and a former offensive lineman for the Kansas City Chiefs. President Theodore Roosevelt was alarmed that there were more than a dozen deaths in the 1905 season and called for a committee to address the issue. Some rule changes, including legalizing the forward pass, came out of those discussions.

And yet, one of the reasons football became popular on college campuses after the Civil War was precisely because of the violence, as the roughness was justified as building character and manliness.

“Those who wanted to have intercollegiate athletics argued that in the wake of the Civil War, boys and men were getting soft because they weren’t being toughened by war,” says historian Richard Crepeau, author of NFL Football: A History of America’s New National Pastime. “In the 1880s and 1890s, those who served in the Civil War were looking at contemporary society and thought we needed activity on college campuses that trained future leaders of America. We needed something to toughen them and train them in leadership, and athletics seemed to answer that need — football perhaps more than any other [sport] — and the [acquired skills of] cooperative action seemed useful in the industrial age.”

The ball’s dimensions began to be standardized in the 1930s, after the National Football League was founded, with another adjustment in 1988. Today, according to the NFL rulebook, footballs are 11 to 11¼ in. long; 28 to 28½ in. around lengthwise, and 21 to 21¼ in. around in the shorter direction. The materials weigh 14 to 15 ounces, and the pressure must be 12½ to 13½ pounds per square inch when its rubber bladder is inflated.

The footballs produced for the Super Bowl were made by hand at Wilson’s Ada, Ohio, factory, which has been making footballs for the NFL since 1941. According to Sports Illustrated, one steer hide weighing approximately 75 lbs. can yield 10 to 12 footballs. The ball’s pebbly texture comes from a 57,000-pound press that also has tiny Wilson Ws in the design, and the bumps are designed to make it easier to catch. Each ball boasts eight white laces, a panel with the NFL shield, the commissioner Roger Goodell’s signature, Wilson’s logo and a longtime nickname for the ball “The Duke,” which was also the nickname of former New York Giants owner and “NFL Patriarch” Wellington Mara. And of course, this year, the ball will feature something special: the Roman numerals LIII, to represent the 53rd Super Bowl.

Write to Olivia B. Waxman at [email protected].