That’s what humans are. Only a thinly woven layer of civilization covers millions of years of selfish animal urges. We wear that civilization like an ill-fitting rental tux, our primitive reptile brains always lurking and ready to burst out. Werewolves, Jekyll and Hyde, Bruce Banner and the Hulk—through such stories we recognize this on some level, but we are still loathe to admit it openly.

Why? people ask at every new atrocity, like this morning’s shooting in Florida. The answer is simple: because that’s what humans do. That’s bleak and pessimistic, some would say. Pragmatic and realistic, I would reply. But to acknowledge our darker selves is not to deny our better angels. Volunteers lined up to donate blood in the wake of the shooting, so many that some had to be turned away.

“You are at your very best when things are worst,” the visiting extraterrestrial of Starman says of humans. It’s a moving line in an Oscar-nominated performance by Jeff Bridges, but the sad truth underlying it is that those worst things have often come from our hands to begin with, as happened at closing time in Orlando’s Pulse nightclub. The Starman could have said, “Some of you are at your best when others are at their worst.”

As eager as we are, through our tribal nature, to delineate those not of our tribe, those who are somehow other and therefore not deserving of our mercy or compassion, the surreal juxtaposition is that throughout the whole of human history and back into our hazy prehistoric past, there has been one human characteristic that crosses all boundaries of race and culture: our capacity for committing violence upon one another for all reasons great and small, from the significant to the nonexistent.

Will we ever rise above this? If a Starman visited us, but did not take human form, would we look out across the sea of human faces around the globe and finally see them all as if simply looking in a mirror? Would we then rise above the tribalism among ourselves—only to unleash it on those extraterrestrials so much more other than our fellow humans have ever been?

How many more millennia of civilization do we need to accumulate until our beasts within are as dead and buried as fossils, to be studied as inanimate relics instead of bloody reality? Or will we continue to stoke those inner flames of hate for all time, always finding some other rationalization, some new justification, to do to others what we would not want done to ourselves?

On days like today, it’s hard to find good answers.