Philip J. Goscienski, M.D.
It's a good bet that 20,000 years ago some kid came back to the cave holding a tiny wolf cub in his arms and asked "Can I keep him?" Maybe it didn't happen just that way but humans have been living closely with animals for thousands of years. It probably didn't take too long before the grown-ups figured out which animals were best left in the forest. Perhaps wolves were the first that were allowed to stay. Cats and their uppity ways must have been latecomers.
It makes a cute story, even though we have no idea how early humans managed to domesticate wild animals. Raising animals as a convenient nearby source of food didn't get started until about 12,000 years ago. Animals as companions and sentries probably came earlier. Their success is undeniable. More than half of American households harbor at least one non-human creature.
Living with an animal exacts a toll that goes far beyond the antics of the canine star of Marley and Me. Simply speaking, all animals come with germs and they sometimes cause disease. These animal-associated illnesses are called zoonoses and there are more than 250 of them. They range from slightly annoying to life-threatening and even the most serious ones may be misdiagnosed because doctors don't always look for them.
Unlike generations past, few Americans are exposed to diseases from farm animals. The exception is an occasional E. coli-infected hamburger. Household pets are another matter, especially when they include less common ones such as reptiles and amphibians.
Snakes and turtles have adapted very well to Salmonella bacteria, for instance but humans, especially young ones, have not. Those tiny turtles that used to be in every pet store are so often colonized with Salmonella that the federal government banned their interstate sale a couple of decades ago.
Except for infections that follow bites, animal-associated diseases can usually be avoided by following a few simple rules of hygiene. Small children should not play with snakes, turtles or lizards because they are often infected with strains of Salmonella. Parents need to impress on children the need to wash their hands when they are done playing with any animal whether at home, at a petting zoo, livestock fair or pet store.
I'll bet that Stone Age kid got to keep his new friend, one of whose descendants eventually showed up as Marley few thousand years later.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at firstname.lastname@example.org.