An attribute of an organism is an adaptation if
(1) the attribute is heritable in some way,
(2) the attribute confers an advantage in survival or reproduction because it enables an individual to resist, or to respond to, an environmental agency or agent that could in principle kill the individual or cause it not to reproduce; and
(3) the agency or agent in question is a real threat to individuals.
!!READ! ! S. E. Speyer, 1988, Biostratinomy and functional morphology of enrollment in two Middle Devonian trilobites. Lethaia 21: 121-138. (The habit of rolling into a ball in trilobites, sowbugs, millipedes, and some other animals.)
Using these three criteria, evaluate the claims for adaptation made by authors of studies about adaptation.
In your one-page paper, 1）very briefly summarize the point the author(s) is (are) trying to make; 2）then briefly indicate which, if any, of the criteria for adaptation have been satisfied; 3）and indicate what additional evidence or alternative hypotheses you would like to see or propose to explain the attribute in question.
You are free to use other published sources; if you do, cite them in full at the end of the paper, on a second page if necessary. do not cite web-sites or popular accounts from newspapers, magazines, or other secondary sources.