The decision  based on a number of current offspring, larger numbers can be greater benefited with  and therefore it's more likely that if the parent had a lot of er offspring then he would continue with the investment and erm the conclusion from  now is that males have a greater reproductive success, therefore they are more likely to desert because they can erm  and erm this  and erm the basic argument of this is one parent can get away with investing less  share of erm resources  they're likely to spend more er  then they're to do it, so in other words erm if, if one of the, of the two  is being to get away with having the other  they can go out to er pursue their own  and therefore erm each partner  force the other to invest more.