Domestic Animals, Dirt and Disease

I recently had learned some interesting things about the Native Americans (my favorite college course was Native American History but somehow it missed a lot of the stuff we now know about what happened around the time European settlers came). The first thing I learned was that there was a great plague that wiped out 90% of the Native population right when Europeans started to settle here. It has been suggested that this depopulation was not entirely related to the Europeans diseases we learned about – small pox, measles, typhoid fever – but may have included a particularly virulent mutation of the deadly Hantavirus – similar to the virus that has been found in the Southwest and has shown up in Appalachia. That doesn’t negate the devastation caused by European disease on the Native Americans though.

Why were European diseases so devastating to Native Americans? Of course Native Americans had never been exposed to European diseases so they couldn’t have formed an immunity to any of them. One of the things you have to wonder about is why did Europeans have so many diseases that were dangerous but didn’t wipe out nearly the entire population and Native Americans had so few but when they did strike they were so completely devastating? Domesticated animals – or the lack of them may be the answer.

Guns, Germs & Steel by Jared Diamond discusses how dense populations that lived with their livestock in Europe was what gave Europeans the advantage since Native Americans had so few domesticated animals (alpacas, llamas, dogs and some fowl). It could be argued that living with livestock and being exposed to so many more zoonotic diseases was actually a disadvantage because people got sick more often, however, being exposed to more disease can increase the immunity of the population and make them less susceptible to catastrophic outbreaks that could wipe out an entire civilization.

The Europeans had developed the ability to fight off these diseases because of antibodies. They help keep you healthy. You can develop your own antibodies and some are passed to you from your mother as a baby. If the mother had been exposed to a disease and survived she could have possibly passed that immunity onto her child. If you got sick from a disease but survived, many times you would be immune to that disease later in life. Our immune system is amazing at it’s ability to adapt and evolve.

But today we face something different. Our immune systems are getting out of whack. Our obsession with eliminating germs may be making things worse for us. Autoimmune diseases, allergies, asthma, and infections have been found to be more common in children that don’t live with animals. Researchers in Finland found that babies raised with dogs (and to a lesser degree cats) were found to be 44% less likely to develop ear infections and 29% less likely to need antibiotics. Speculation is that the germs a dog brings in with them help a baby’s immune system mature faster.

Other researchers are looking at the rate of allergies among children, which has increased 2 to 5 times in the last 30 years. What they found is that children that grow up on farms, particularly the Amish, have very low rates of allergies. It’s yet to be determined what exactly is responsible for this difference, but livestock are quite possibly part of the equation.

Of course the other side of the coin is our overuse of antibacterial products. The few germs that get through our new indoor environment (children on average now spend less than 8 minutes a day playing outside) are now wiped out with disinfectants and antibacterial soaps. Kids that were found to have parabans and/or triclosan, common antibacterial chemicals found in many household products, in their blood system were twice as likely to develop environmental allergies. Triclosan was found to increase the risk of food allergies, which can be fatal, two fold. The problem though isn’t necessarily the triclosan or parabans, it’s that these chemicals are keeping kids’ immune systems from developing by fighting off germs.

It seems that living with animals, playing outside and not using antibacterial products may have a benefit to kids and the greater population. I guess, in this case what doesn’t kill you actually does make you stronger.