sorry I was referring to the initial question. what part of the body could be designed better my answer was beta 1 receptors and there is primary reference supporting my claim. I don't care about how they came about the important thing is fixing the problem. thats just my opinion. the actual design of the receptor is the problem it is not perfect infact their are mutations that make it stimulate Adenylate cyclase at an unhealthy level leading to cardiomyopathy (heart disease)This mutation has become so prevelent that it can now be considered wild type and thus provoke an investigation of mankinds own effects on our natural selection. LOL if it indeed exists!