▁contributions ▁( which ▁are ▁typically ▁relatively ▁small ▁in ▁the ▁West ▁African ▁sav anna ▁and ▁sah el , ▁where ▁pol yg yn y ▁rates ▁are ▁higher ), ▁finding ▁that ▁pol yg yn y ▁rates ▁decrease ▁significantly ▁with ▁child ▁mort ality ▁rates . ▁ ▁Types ▁of ▁pol yg yn y ▁ ▁Pol yg yn ous ▁mar ri ages ▁fall ▁into ▁two ▁types : ▁sor oral ▁pol yg yn y , ▁in ▁which ▁the ▁co - w ives ▁are ▁sister s , ▁and ▁non - s or oral , ▁where ▁the ▁co - w ives ▁are ▁not ▁related . ▁Pol yg yn y ▁offers ▁hus b ands ▁the ▁benefit ▁of ▁allowing ▁them ▁to ▁have ▁more ▁children , ▁may ▁provide ▁them ▁with ▁a ▁larger ▁number ▁of ▁product ive ▁workers ▁( where ▁workers ▁are ▁family ), ▁and ▁allows ▁them ▁to ▁establish ▁polit ically ▁useful ▁t ies ▁with ▁a ▁greater ▁number ▁of ▁kin ▁groups . ▁Senior ▁w ives ▁can ▁benefit ▁as ▁well ▁when ▁the ▁addition ▁of ▁junior ▁w ives ▁to ▁the ▁family ▁light ens ▁their ▁work load . ▁W ives ', ▁especially ▁senior ▁w ives ', ▁status ▁in ▁a ▁community ▁can ▁increase ▁through ▁the ▁addition ▁of ▁other ▁w ives , ▁who ▁add ▁to ▁the ▁family ' s ▁prosper ity ▁or ▁symbol ize ▁consp ic uous ▁consumption ▁( m uch ▁as ▁a ▁large ▁house , ▁domestic ▁help , ▁or ▁expensive ▁vac ations ▁operate ▁in ▁a ▁ ▁western ▁country ). ▁For ▁such ▁reasons , ▁senior ▁w ives ▁sometimes ▁work ▁hard ▁or ▁contribute ▁from ▁their ▁own ▁resources ▁to ▁enable ▁their ▁hus b