AUSTIN, Texas -- In times of trouble, Americans are very, very generous.
We've raised billions of dollars for major disasters at home and abroad: 9-11, Hurricane Katrina, the Haiti earthquake and the Indian Ocean tsunami, among them.
Now we've rallied around the people affected by the Boston Marathon bombing, and, much closer to home, the West, Texas, fertilizer plant explosion. Within minutes of both disasters, Americans already were putting together fund-raisers, goods drives and volunteer efforts.
We do it so instinctively, so naturally, that we don't even stop to question it.
But why do we do this? Is there something else going on here other than kindness, compassion and a need to help our fellow man? Yes, actually. There is. And it starts with our basic nature as human beings, says Art Markman, a psychology professor at the University of Texas.
People are wired for routine, he said. We wake up, take a shower, go to work, go home and go to sleep, day after day after day. Then something very bad happens. People end up dead or suffering or homeless. Then suddenly, sometimes subconsciously, the idea of our own deaths becomes painfully real.
"We have to grapple with that, somehow," Markman said.
Enter the terror management theory. This theory, pushed by social psychologists, posits that in the face of tragedy, humans start clinging to their cultural belief systems to boost their self-esteem.
Translation? We remember we're mortal, freak out, start looking for the meaning of life, hold on to the idea that most people are good, jump into action and start to feel useful. Anxiety gone, life goes on.
But the brain is complicated, Markman said. We process events in ways we're not even aware of until the crisis has passed.
"This is our automatic reaction," he said. "It's not explicit reasoning like, 'Let me think about this. Oh my God, how will I ever deal with the existential anxiety that comes from being mortal?"'
Whatever the reason for it, disasters obviously trigger a passionate need to act. Marty McKellips, regional chief executive officer of the American Red Cross, sees it all the time.
The problem, she said, is trying reconcile that passion with the actual needs of the affected community. After a traumatic event, people collect clothing, toiletries and food long after those needs have been met.
But charities don't want to make people feel rejected either, particularly when it's obviously part of the healing process, McKellips said.
"I tell people, 'You're going to have this feeling every time this happens, so what you can do is become trained to be a Red Cross volunteer and then you can make a difference,"' she said.
Since Wednesday -- the day the West plant exploded -- more than 100 people have signed up to do just that.