This kind of defect is really not difficult to understand. To me it’s almost more shocking that it doesn’t happen more often. Think of how often computers crash or data gets corrupted on any kind of document. That’s just a few thousand or hundred thousand bits of code or info, and it gets ganked up all the time.
Now think of how complex the information that makes up the humane genome is (roughly three billion base pairs per strand of DNA), and how many times that strand has to be copied, perfectly, in order for a baby to be born with ten fingers and toes – no more, no less – and you get an idea how easy it would be for this to happen.
Keep wreves in General Talk in 2011!