There is real meaning in the concept of the selfish gene

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in lab virology. If you take a bad, mean, disease causing germ and grow it in cells in a dish, it will very rapidly adapt to growing in the dish and lose the ability to cause disease in the original host. Unless someone has been growing smallpox in susceptible people who die from it, instead of growing it in a dish (and it grows in a dish easily but loses genes rapidly), it's not likely that even surviving samples of it cause disease reliably.

Dr. Matt