Chicago Cubs
© Henryk Sadura / ShutterstockWrigley Field in Chicago, Ill., home of the Chicago Cubs.
Forest Preserve police in Cook County, Ill., found a grisly discovery this week: a decapitated white goat tied to a tree near the Indian Boundary Golf Course. That was strange enough, but last Wednesday an unknown man delivered a smelly box addressed to Tom Ricketts, the owner of the Chicago Cubs baseball team. Inside was a decaying goat's head.

Officials are investigating whether the headless goat is connected to the goat head delivered to Wrigley Field last week.

Who would send a severed goat head to Wrigley Stadium? A confused Satanist? An angry mobster trying to send a threat but unable to find a horse?

No, it is a response to a supposed "Billy Goat" curse that dates back to 1945 when a man named Bill "Billy Goat" Sianis had a pet goat (named Murphy) that was refused entry to a Cubs game. Offended by the affront, according to legend he cursed the club with the words, "The Cubs ain't gonna win no more!"

Sure enough, the Cubs lost the next game and have not won a World Series in over a century despite many fan attempts over the years to lift the curse (some of them involving goats). While some regard the curse as merely a silly superstition, many longtime fans take it very seriously.

Belief in the Billy Goat curse set the stage for what happened in 2003 when a Cubs fan named Steve Bartman reached for - and deflected - a foul ball in Game 6 of the National League Championship Series that might have been caught by an outfielder.Bartman was widely blamed for the Cubs' loss by both fans and the news media, and received harassment and death threats.

In an ESPN documentary film about that incident titled Catching Hell, Benjamin Polak, a professor of economics at Yale University, who analyzed the Cubs' chances of winning at each stage of the game, points out that Bartman's catch only decreased the team's chance of winning by 3 percent; far worse errors were made by the Cubs' players themselves throughout that game. Yet many players and fans had been looking for a bad omen, some superstitious sign that their dreams of a long-awaited victory would be spoiled - and Bartman was it. As Polak noted, any team of professional athletes should be able to easily overcome a 3-percent deficit introduced by a random event like fan interference.

Psychology of the Curse

There are countless superstitions involving everything from spilled salt to black cats to nailing horseshoes over doors, though few of them involve animal sacrifices. The choice of a goat in the Cubs curse is ironic, since it is a literal embodiment of the scapegoat - a goat that in ancient times was chosen to bear the burdens of villagers' sins, and was then led out of town never to return (or sacrificed).

Curses, spells, and black magic seem like anachronisms held over from Salem, Mass., in the 1690s. Surely nobody in 2013 America believes in such things, right? In fact superstitions are all around us. Many office and apartment buildings, for example, are missing a 13th floor, and some airplanes don't have a 13th row. There's a reason why the Beijing Olympics began at exactly 8:08:08 p.m. local time on 8/8/08: The number 8 is considered lucky in China, and thus the games began at the most auspicious time possible.

Superstitions are common in sports and competitions; for example, some professional tennis players eat exactly the same meals and stay in the same rooms at the same hotels following a big win. They think that their success must have something to do with circumstances beyond their abilities. Poker players will wear the same "lucky" shirt they were wearing when they hit it big, and so on.

This is a logical fallacy with a Latin name: post hoc ergo propter hoc ("after this, therefore because of it"), also known as faulty causation. The human brain seeks causes, and will find them even when they don't exist. We did something, then something bad happened. We did something else, and things were okay, so what we did the first time must have caused the bad things to happen.

Superstition and magical thinking come easily to humans; we jump to conclusions without evidence; our biases and prejudices influence how we interpret the world. We see faces in clouds and patterns in events where they do not exist. It shouldn't be surprising that superstitions have always been with us. The brain's tendency to find meaningful patterns in both meaningful and meaningless stimuli is also called patternicity. In his book "The Believing Brain" (St. Martin's Griffin, 2012), publisher of "Skeptic" magazine Michael Shermer notes that evolutionary psychology may help explain our tendency toward magical thinking. "There was a natural selection for the cognitive process of assuming that all patterns are real and that all patternicities represent real and important phenomena. We are descendants of the primates who most successfully employed patternicity."

So is the Billy Goat curse real? It might be real in one way: Curses sometimes work for the same reason that placebos sometimes work: because people believe in them. Confidence and focus are important to athletic success, and if a player loses confidence for any reason - including a real or imagined curse - it can affect their performance in very real ways. Either way, the sooner the Cubs win a championship, the sooner goats can rest easier.