▁associated ▁with ▁domestic ation . ▁The ▁Amer icas ▁extend ▁mainly ▁north ▁and ▁south , ▁which , ▁according ▁to ▁the ▁environmental ▁determin ist ▁theory ▁popular ized ▁by ▁J ared ▁Diam ond ▁in ▁G uns , ▁Germ s , ▁and ▁Ste el , ▁meant ▁that ▁it ▁was ▁much ▁harder ▁for ▁cultiv ated ▁plant ▁species , ▁domestic ated ▁animals , ▁and ▁dise ases ▁to ▁migr ate . ▁ ▁Bi ological ▁war fare ▁ ▁When ▁Old ▁World ▁dise ases ▁were ▁first ▁carried ▁to ▁the ▁Amer icas ▁at ▁the ▁end ▁of ▁the ▁fif teenth ▁century , ▁they ▁spread ▁throughout ▁the ▁southern ▁and ▁northern ▁hem is pher es , ▁leaving ▁the ▁ind igen ous ▁populations ▁in ▁near ▁ru ins . ▁No ▁evidence ▁has ▁been ▁discovered ▁that ▁the ▁earliest ▁Spanish ▁colon ists ▁and ▁mission aries ▁deliber ately ▁attempted ▁to ▁inf ect ▁the ▁American ▁n atives , ▁and ▁some ▁effort ▁was ▁actually ▁made ▁to ▁limit ▁the ▁dev ast ating ▁effects ▁of ▁disease ▁before ▁it ▁killed ▁off ▁what ▁remained ▁of ▁their ▁forced ▁slave ▁labor ▁under ▁their ▁en com i enda ▁system . ▁The ▁cattle ▁introduced ▁by ▁the ▁Spanish ▁cont amin ated ▁various ▁water ▁res erves ▁which ▁Native ▁Americans ▁d ug ▁in ▁the ▁fields ▁to ▁accum ulate ▁rain water . ▁In ▁response , ▁the ▁Francis c ans ▁and ▁Domin icans ▁created ▁public ▁f ount ains ▁and ▁aqu ed uct s ▁to ▁guarantee ▁access ▁to ▁drink ing ▁water . ▁But ▁when ▁the ▁Francis c ans ▁lost ▁their ▁privileges ▁in ▁ 1 5 7 2 , ▁many ▁of ▁these ▁f ount ains ▁were ▁no ▁longer