Imagine it’s about 200,000 years ago: Two people are sitting around a watering hole, both freshly branched onto the new evolutionary path of modern humans. Suddenly, they hear a twig snap behind them. One of them jumps up, eyes wide, ears tuned, muscles tensed. The other one stretches their legs and says, “It’s probably nothing.”

So, who’s your ancestor?

Your amygdala, the fire alarm of your brain, devotes two-thirds of its neurons to scanning for negatives.

Probably not the chilled-out one. All of us are descended from early humans who had a bias toward noticing the negative. It’s one of the things that keeps us all alive. Missing the cues for something you can eat, like an apple, isn’t that big a deal. But missing the signal that something is going to eat you–that’s a problem of existential proportions.

And so your amygdala, the fire alarm of your brain, devotes two-thirds of its neurons to scanning for negatives. We notice angry faces more quickly and easily than happy faces. Pain teaches us faster than pleasure.

When we notice something negative, our hippocampus lays the memory down almost immediately. But guess how long you have to hold something positive in your awareness in order to have it laid down as a memory? That takes 12 full seconds. As psychologist Rick Hansen has said, the “brain is like Velcro for negative experiences but Teflon for positive ones.”

So we are primed to notice our mistakes–notice our boss is upset with us, notice our audience is bored, notice that tone of disapproval in our parent’s voice. These act as trip-wires in our brains and make us less rational, less creative, less productive, and less happy. From an evolutionary point of view, what got us here–our negativity bias–won’t get us there, wherever it is we’re trying to go with our personal and professional lives.