The Ones Who Never Leave

There are eight-legged animals living in your pores. Not visiting. Living. They were born there, in the small dark tunnels at the root of your eyelashes, and they will die there, and they have never once seen light. They have no eyes to see it with. They are called Demodex, and they are perhaps a millimetre long, and at this moment, while you read this, they are moving very slowly across your face. Slowly enough that you cannot feel them. They come out at night, when it is warm and still, and they find each other, and they make more of themselves, and then they go back down into the dark before morning. Scientists used to think that only some people carried them. Then better tools arrived. Now the answer appears to be: everyone. Every adult human face on Earth. Your grandmother. Your doctor. Every person in every painting in every museum. They were there in the caves. They were there in the pharaohs' tombs. And here is the part that will not let you go: they have been with us so long, living so close, that they have lost the genes they no longer need. They are becoming simpler. They are, in some direction science does not yet have a name for, becoming part of us.