Been using no shampoo or anything besides water in my hair for over 10 years and it has been great. Just water on the rest of the body too - the way hominids have been cleaning themselves for millions of years before the inventions of soap and shampoo. 

 This. 

 Well I am surely not pro modern shampoo. Anyhow soap has been invented about 4500 years ago and today people get much older and are healthier, one of the key aspects is a better hygiene.