What do you need to be an effective sniper? A good spotter, a good scope, a good rifle, and apparently, if you’re a female assassin with a bad case of scoliosis (how does her butt even get like that?), you need a heart rate so slow that your skin turns blue. The aforementioned assassin is Amélie Lacroix, a character in the incredibly popular team shooter Overwatch. Her blue skin is the result of a reduced heart rate–ostensibly, fewer heart beats means fewer tremors to correct for while aiming–but why would a slow ticker turn and keep the color of skin? And would she stay that way forever?

In my latest Because Science, I’m examining Widowmaker and making a diagnosis. First of all, your skin can turn blue during a condition called cyanosis, where there is not enough oxygen in the blood or the body’s tissues. If Lacroix had a supremely slow heart rate, it could in fact cause cyanosis by not getting blood around her body fast enough to supply her oxygen-starved cells. But there are still questions left unanswered. Blood is never blue despite what your veins look like, so why does skin turn blue without oxygen in the blood?

It has to do with the physics and chemistry of the molecular machinery that transports oxygen around the body. To find out why, and why Widowmaker won’t always be blue because of it, check out my latest episode above.

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