THUMBS

摘要

It started as party chatter. My hands are different sizes, not so much that most people can tell, but I can. The real difference is the thumbs. The distal joint of my right thumb, but only the right one, bends back 90°, 'hitchhiker's thumb'. The medical term is distal hyperextensibility. It's an autosomal recessive trait, so theoretically you can't have just one. At parties, I said, "I have someone else's hand. When they were putting me together, somebody dropped a hand and stepped on it, so they had to go for spare parts." Great conversation starter, for a while. Then I read about the Chimaera Project. A chimaera is an organism composed of two genetically distinct cell lines. Natural chimaeras occur when fraternal twin embryos fuse early enough to develop into a single entity, with no extra limbs or organs.