▁▁ ▁Daw kins ▁begins ▁the ▁book ▁by ▁stating ▁that ▁all ▁our ▁ancest ors ▁reached ▁ad ul th ood ▁and ▁beg ot ▁at ▁least ▁one ▁child ▁before ▁they ▁died . ▁In ▁a ▁world ▁where ▁most ▁organ isms ▁die ▁before ▁they ▁can ▁pro create , ▁descend ants ▁are ▁common ▁but ▁ancest ors ▁are ▁rare . ▁But ▁we ▁can ▁all ▁claim ▁an ▁un bro ken ▁chain ▁of ▁successful ▁ancest ors , ▁right ▁back ▁to ▁the ▁first ▁single - cel led ▁organ ism . ▁ ▁If ▁the ▁success ▁of ▁an ▁organ ism ▁is ▁measured ▁by ▁its ▁ability ▁to ▁surv ive ▁and ▁reproduce , ▁then ▁all ▁living ▁organ isms ▁can ▁be ▁said ▁to ▁have ▁inherited ▁" good ▁gen es " ▁from ▁successful ▁ancest ors . ▁Each ▁generation ▁of ▁organ isms ▁is ▁a ▁s ieve ▁against ▁which ▁rep licated ▁and ▁mut ated ▁gen es ▁are ▁tested . ▁Good ▁gen es ▁fall ▁through ▁the ▁s ieve ▁into ▁the ▁next ▁generation ▁while ▁bad ▁gen es ▁are ▁removed . ▁This ▁explains ▁why ▁organ isms ▁become ▁better ▁and ▁better ▁at ▁whatever ▁it ▁takes ▁to ▁succeed , ▁and ▁is ▁in ▁stark ▁contrast ▁to ▁L amar ck ism , ▁which ▁would ▁require ▁successful ▁organ isms ▁to ▁ref ine ▁their ▁gen es ▁during ▁their ▁lifetime . ▁ ▁Following ▁this ▁gene - center ed ▁view ▁of ▁evolution , ▁it ▁can ▁be ▁argued ▁that ▁an ▁organ ism ▁is ▁no ▁more ▁than ▁a ▁temporary ▁body ▁in ▁which ▁a ▁set ▁of ▁companion ▁gen es ▁( act ually ▁alle les ) ▁co - oper ate ▁toward ▁a ▁common ▁goal : ▁to