The second category of cell death genes includes those that hasten cell death accidentally and, therefore by definition, did not evolve for this purpose.
Conceptually, the genes responsible for cell death can be grouped into two main categories, those selected during evolution to cause cell suicide and those that did not evolve for this purpose (accidental cell death).
As outlined above, however, even if an MS-OP is currently involved in dimerization, this does not necessarily imply that it initially evolved for that purpose.
But the general consensus among those interested is that permanent breasts evolved for the purpose of sexual attraction.
Evolutionary analyses rule out the hypothesis that the brain mechanisms that cause race encoding evolved for that purpose.
If Anchiornis and Archaeopteryx were ancestral birds, it would appear that that feathers, which Feduccia shows to be complex, intricate structures well adapted for flight, evolved for that purpose.
Experimentally eliciting thoughts and feelings of romantic love an emotion thought to have evolved for the purpose of relationship maintenance reduced attention to alternative partners at an early, automatic stage of visual perception.
A different approach to characterizing and possibly for identifying and delimiting inheritance systems posits that to count as an inheritance system a system has to have evolved for the purpose of transmitting hereditary information, i.e., to have the "meta-function" of producing heritable phenotypes (Shea 2007).
Most cells in metazoans do not die because they are damaged or lack nutrients; they die because they kill themselves through activation of a mechanism that has evolved for that purpose.
Though the visual word form area of the human brain appears exquisitely tuned to the act of reading, it could not have evolved specifically for this purpose.
