At 11:35 EST on May 1, 2011 the United States and the world were provided with information that thousands have been waiting for for nearly a decade: Osama bin Laden is dead. President Barack Obama in a televised news conference informed the world that a US special forces team had raided a compound in Pakistan and killed the Al Qaeda leader. Almost immediately people started to gather outside the White House in Washington, DC and what started with 30-40 revelers turned into a world-wide event that stretched to Times Square and a Mets/Phillies game in NYC and even took hold in Athens, Ohio.

Many in the media have embraced the impromptu celebrations, and even Rush Limbaugh praised the actions of the Obama Administration (though he has since backtracked). Still, some have questioned their appropriateness, and what it says about our civilization. Recently, on the Huffington Post, Dr. Pamela Gerloff wrote about the psychology of revenge and why we shouldn’t celebrate the death of Osama bin Laden. That sentiment has spread around the social networking site Facebook in the form of a false Martin Luther King, Jr. quote,

“I mourn the loss of thousands of precious lives, but I will not rejoice in the death of one, not even an enemy. Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that.”

While it appears that the heroic, transformational civil rights leader never said these exact words, the comments are not unreasonably assigned to him, and the sentiment is the key.

A genuine, visceral backlash in response to the peaceful, patriotic mobs seen on the streets of the US and around the world is emerging in text messages, emails, tweets, and op-eds. I use the term mob here, because that is what the groups of revelers are, they are mobs. However, much like flash mobs, these are non-violent celebrations, which provide safe places to express emotions about an identified enemy and our nation. While some are morally outraged that people are celebrating the death of another human, some are skeptical of the patriotic feelings of those involved, and are uncomfortable with the public display.

In her article, Dr. Gerloff stated that, “”Celebrating” the killing of any member of our species — for example, by chanting “USA! USA!” and singing “The Star Spangled Banner” outside the White House or jubilantly demonstrating in the streets — is a violation of human dignity. Regardless of the perceived degree of “good” or “evil” in any of us, we are all, each of us, human. To celebrate the killing of a life, any life, is a failure to honor life’s inherent sanctity.” Instead, she suggested that the death of Osama bin Laden provides us with an opportunity to assess what kind of nation and species we want to be. She went on to say that, “We could start by not celebrating the killing of another.” To her credit, Dr. Gerloff stated that, “We are not a peaceful species. Nor are we a peaceful nation. The celebrations of this killing throughout the country draw attention to these facts.” However, I would argue that she and the other critics and detractors are missing an important lesson that this historic moment offers to teach us.

The reaction of thousands around the US and the world provides us with a glimpse into our own psychology. Not the psychology that has developed over the course of our lifetimes, but the psychology that has evolved over million of years of partially closed social groups of related males competing violently with other groups for resources and territories. The impromptu celebrations that began around midnight Monday morning and lasted well into the early morning hours were not planned, they were not organized, they were the rawest of human emotion and data. Those gatherings were the result of the human mind and collective experience being exposed to a life-threatening traumatic event (9/11), then provided with one, centralized cause and target of that event. The final piece of the puzzle was provided with President Obama’s address of the nation late Sunday night. Osama bin Laden, for many, represented evil, but beyond that, he represented the source of an invasion on our way of life. He was the ultimate “outsider” and the target of deep lethally xenophobic feelings that were both justified and accentuated by our government, the media and bin Laden himself.

As the leader of Al Qaeda, Osama bin Laden took it upon himself to antagonize, demonize and threaten the United States. While he may have thought that it was necessary for his own survival, when he claimed responsibility for the deaths of over 3000 Americans, the die was cast. The reaction of ordinary citizens to the news that he was dead was predictable, almost unavoidable from the perspective of evolutionary psychology. It was the reaction of a group of primates, celebrating in the elimination of a threat and rival. In those hours after the announcement, it was nothing more, nothing less, and we need to understand that. We need to understand that for all of our language and culture and “civilization” we are, at our core as a species, a lethally xenophobic primate.

In her article, Gerloff suggests that, “We will only have peace when we stop the cycle of jubilation over acts of violence. Who will stop the cycle? If not us, who? If not you and I, who will it be?” This is an admirable intellectual position to take, and one that I agree with in principle. However, it is naïve to think that we as a group can simply put aside our evolved behaviors and emotions and embrace a new psychology to “consciously evolve” toward the kind of species we aspire to be. Instead, we need to understand why the death of a leader from another community matters, and why we have such strong emotional reactions to it.