In December 2008, journalist, Muntadhar al-Zaidi yelled, "This is a farewell kiss from the Iraqi people, you dog!" as he threw his shoes at President George W. Bush.

In December 2008, journalist, Muntadhar al-Zaidi yelled, "This is a farewell kiss from the Iraqi people, you dog!" as he threw his shoes at President George W. Bush.

At the time, the incident appeared to be little more than the ravings of a disgruntled loon, but more recent events suggest al-Zaidi inaugurated a whole new "fashion" of protest.

Just this week former Secretary of State Hillary Clinton became the latest target of a shoe-flinging protestor. While Clinton addressed a meeting of the Institute of Scrap Recycling Industries in Las Vegas, Nevada, a female audience member threw a black and orange athletic shoe her way.

Since the Bush "shoeing" of 2008, more than three dozen world leaders and prominent business executives have been footwear fodder. The list includes Chinese Premier Wen Jiabao, Iranian President Mahmoud Ahmadinejad, Indian Home Prime Minister Palaniappan Chidambaram, Sudanese President Omar al-Bashir, Greek Prime Minister George Papandreou, UK Prime Minister Tony Blair and more than two dozen other notable figures.

All these slipper slinging incidents beg the question: why shoes?

During the 2008 Bush affair, many pundits noted that shoe bottoms are considered unclean in certain cultures, especially in the Muslim world. While this may be a contributing factor, there is likely a much simpler explanation. In most public meetings people are permitted to wear shoes. Shoes come on and off easily. Shoes, especially those of the leather dress variety can have heels that are heavy and sharp.

While their shape makes them aerodynamically unpredictable — as evidenced by the preponderance of near misses — they’re easy to throw. And, admittedly, there is something implicitly dirty about a shoe. We didn’t evolve the colloquial term, "bootlicker" because boot bottoms are clean.

In short, portability, innocuousness, heft, symbolic content and ease of launch make shoes a reasonable choice for the emotionally disturbed malcontent. Of course, shoes are but the latest trend in a venerable tradition of political protest. As far back as the first century AD, the Roman emperor, Vespasianus Caesar Augustus, was pelted with turnips during a riot at Hadrumetum.

History records many aggrieved fusillades. Among the more colorful is an excerpt from the Old Bailey courthouse in London, where criminals would be confined to pillories and "pelted with rotten eggs and vegetables, blood and guts from slaughterhouses, dead cats, mud and excrement, and even bricks and stones."

Such traditions have extended to religious protests and theatrical critiques as well. There are innumerable instances from the 19th century where newspapers reported a speaker or performer receiving a hail of rotten food, stones, chairs and other undesirable items.

This long history of throwing things at people begs the question as to why we as a society have largely abandoned this as a primary way to show public discontent.

The social scientist, David Garland, notes that the move from this kind of expression has occurred because bodily punishments offend modern "repressive" sensibilities. As Garland states, "Gross violence, deliberate brutality, the infliction of physical pain and suffering, all these are felt by many people to be intolerably offensive in themselves and to have no legitimate place within the public policy and legal institutions of a civilized nation."

Perhaps that helps to explain both the increasing rarity of such attacks — as evidenced by their newsworthiness — and the change in projectiles. Nobody is likely to be seriously injured by a shoe, but they still serve as an effective proxy for an age when the things thrown were as dangerous as the sentiments behind them.