▁of ▁ 1 0 0 ▁million ▁or ▁more . ▁Contact ▁with ▁the ▁Europe ans ▁led ▁to ▁the ▁European ▁colon ization ▁of ▁the ▁Amer icas , ▁in ▁which ▁millions ▁of ▁imm igr ants ▁from ▁Europe ▁eventually ▁settled ▁in ▁the ▁Amer icas . ▁ ▁The ▁population ▁of ▁African ▁and ▁E uras ian ▁pe op les ▁in ▁the ▁Amer icas ▁grew ▁stead ily , ▁while ▁the ▁ind igen ous ▁population ▁pl um met ed . ▁E uras ian ▁dise ases ▁such ▁as ▁influen za , ▁p neum onic ▁pl agues , ▁and ▁small po x ▁dev ast ated ▁the ▁Native ▁Americans , ▁who ▁did ▁not ▁have ▁imm unity ▁to ▁them . ▁Conf lict ▁and ▁out right ▁war fare ▁with ▁Western ▁European ▁new com ers ▁and ▁other ▁American ▁tribes ▁further ▁reduced ▁populations ▁and ▁dis rupted ▁traditional ▁soci eties . ▁The ▁extent ▁and ▁causes ▁of ▁the ▁decl ine ▁have ▁long ▁been ▁a ▁subject ▁of ▁academic ▁debate , ▁along ▁with ▁its ▁character ization ▁as ▁a ▁gen o cide . ▁ ▁Population ▁over view ▁ ▁Given ▁the ▁fragment ary ▁nature ▁of ▁the ▁evidence , ▁even ▁semi - ac cur ate ▁pre - Col umb ian ▁population ▁figures ▁are ▁impossible ▁to ▁obtain . ▁Sch ol ars ▁have ▁varied ▁widely ▁on ▁the ▁estimated ▁size ▁of ▁the ▁ind igen ous ▁populations ▁prior ▁to ▁colon ization ▁and ▁on ▁the ▁effects ▁of ▁European ▁contact . ▁Est im ates ▁are ▁made ▁by ▁ext rap ol ations ▁from ▁small ▁bits ▁of ▁data . ▁In ▁ 1 9 7 6 , ▁ge ograph er ▁William ▁D ene van