▁the ▁ant agon istic ▁ple iot ropy ▁hypothesis , ▁which ▁was ▁first ▁developed ▁by ▁G . C . ▁Williams ▁in ▁ 1 9 5 7 . ▁Williams ▁suggested ▁that ▁some ▁gen es ▁responsible ▁for ▁increased ▁fit ness ▁in ▁the ▁younger , ▁fert ile ▁organ ism ▁contribute ▁to ▁decre ased ▁fit ness ▁later ▁in ▁life , ▁which ▁may ▁give ▁an ▁evolution ary ▁explanation ▁for ▁sen esc ence . ▁An ▁example ▁is ▁the ▁p 5 3 ▁gene , ▁which ▁suppress es ▁cancer ▁but ▁also ▁suppress es ▁stem ▁cells , ▁which ▁re pl en ish ▁worn - out ▁t issue . ▁ ▁Unfortunately , ▁the ▁process ▁of ▁ant agon istic ▁ple iot ropy ▁may ▁result ▁in ▁an ▁alter ed ▁evolution ary ▁path ▁with ▁delayed ▁adaptation , ▁in ▁addition ▁to ▁effectively ▁cutting ▁the ▁overall ▁benefit ▁of ▁any ▁alle les ▁by ▁roughly ▁half . ▁However , ▁ant agon istic ▁ple iot ropy ▁also ▁l ends ▁greater ▁evolution ary ▁" st ay ing ▁power " ▁to ▁gen es ▁cont rolling ▁benef icial ▁tra its , ▁since ▁an ▁organ ism ▁with ▁a ▁mut ation ▁to ▁those ▁gen es ▁would ▁have ▁a ▁decre ased ▁chance ▁of ▁successfully ▁reprodu cing , ▁as ▁multiple ▁tra its ▁would ▁be ▁affected , ▁potentially ▁for ▁the ▁worse . ▁ ▁S ick le ▁cell ▁an emia ▁is ▁a ▁classic ▁example ▁of ▁the ▁mixed ▁benefit ▁given ▁by ▁the ▁stay ing ▁power ▁of ▁ple iot rop ic ▁gen es , ▁as ▁the ▁mut ation ▁to ▁H b - S ▁provides ▁the ▁fit ness ▁benefit ▁of ▁mal aria ▁resistance ▁to