Found on bash.org :
“I have a sore throat.”
2000 BC : “eat this root”
1200 AD : “That root is heathen, say this prayer.”
1500 AD : “That prayer is superstition, drink this elixir.”
1800 AD : “That elixir is snake oil, Take this pill.”
1900 AD : “That pill is ineffective, Take this antibiotic.”
2000 AD : “That antibiotic is artificial, Here why dont you eat this root.”
Except that the advent of antibiotics is usually dated to 1928. See http://en.wikipedia.org/wiki/Penicillin.
(End of nitpicking)