Is there an easy way to find free, full-length articles that contain biological contingency analysis?
For biology or biomedicine, Pubmed is the way to go. Most articles published in the last 15 years should be online and accessible via the full-text link that appears at the upper right of the listing; this will have a different appearance depending on the publisher. If that’s not there, sometimes you can find the article in question by going directly to the journal’s web site. If you are accessing the internet from on campus, or if the paper is in a special depository called PubmedCentral, you should have access to the journals’ full text (I am assuming you are at a college big enough to purchase a wide range of journals.) Otherwise, hie yourself over to your local medical or science library and buckle down.