"In 1978, the first History of Programming Language Conference (HOPL) 
described the development of 13 computer programming languages, the 
people who participated in that work, and the context in which it was 
undertaken. In 1993, HOPL-II contained 14 papers on the genesis and 
evolution of programming languages. It is time for HOPL-III, to be held 
with FCRC 2007 in San Diego. Each HOPL-III paper should detail the early 
history or evolution of a specific programming language. Preliminary 
ideas about each language should have been documented by 1996 and each 
language should have been in use by 1998."


http://research.ihost.com/hopl/

Ruby meets the age criteria.


-- 
James Britt

"Programs must be written for people to read, and only incidentally
  for machines to execute."
   - H. Abelson and G. Sussman
   (in "The Structure and Interpretation of Computer Programs)