Simplify the following text for a Grade 10 native English-speaking person.
Original: An early alternative method for curling hair that was suitable for use on people was invented in 1905 by German hairdresser Charles Nessler .
Simplified: The first chemical treatment for curling hair that was suitable for use on people was invented in the year 1906 by the German hairdresser Karl Nessler ( 1872-1951 ) .