We know that pain is a biological response to injury. In past posts I've called it our sixth sense. Pain makes us aware of damage and calls our attention to the need to protect the injured area.

It turns out that pain may do more. Pain may help us stay alive.

In a recent study focusing on squid, scientists compared the survival rate of injured squid after attacks by black sea bass. The scientists clipped the tip of a single tentacle of a group of squid. Half of the group's tentacles were then treated with anesthetic. The others were left untreated. The squid were then placed in a tank with one of their natural predators, black sea bass.

The untreated squid became what the scientists called hypervigilant. In other words, they paid close attention to where the sea bass were and what they did at all times. The squid whose injury had been anesthetized didn't modify their behavior. The researchers found that the hypervigilant squid survived attacks more often. While scientists cannot know whether squid actually perceive pain, they concluded that the squid's perception of injury made them more vigilant about potential threats.

What does this mean?

Well, it gives us a possible evolutionary reason for pain. If humans are like squid and pain makes us hyper vigilant when confronted with danger, then perhaps those of us more sensitive to pain stimuli were selected out for survival.

Why does this matter?

When scientists can fully understand the biological purpose of pain, then they are closer to understanding how to treat pain when it goes awry.

For those of you that like to read the technical stuff, the original study appeared in the May issue of Current Biology.

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