For living authors in academia, this information is not always readily available. Current library practice only requires dates to be added to an author's name when there is a potential confusion with another similarly-named author.

The current Library of Congress authority record for Paul Collier - which is the official site in the US for standardized author information - does not give a birth date. None of the biographical notes I found on the web give this information, either. You could consider contacting him personally using the contact info search for the University of Oxford, where he is a professor of economics. (Or just see his page.)


The same goes for Easterly's LoC authority record, and likewise some web searching doesn't reveal a birth date. Again similarly, if you are really set on getting his birth year, you could consider contacting him through the information on his NYU home pages.