I once spent some time in remote areas of South America. There was no electricity or running water and the sanitation system was a hole in the ground. Mosquitoes the size of humming birds were feasting on me through my denim jeans and when I asked for a drink of water I was given a cup and told to walk past the mangy, rabid looking animals and dip it in the Orinoco Delta, (a river I was too scared to put my toe in let alone drink from.) What struck me most were the happy, healthy, naked, mozzie bite-free children running around.
In communities like these the people have adapted to their environments a lot better than we have in the western world. From the moment they are born they are exposed to the multitude of germs that they live with every day. Their immune systems mature very quickly. They have to in order to deal with fighting off serious diseases such as Typhoid, Malaria and a whole range of parasites. There is no sterilizing baby’s bottle here.