Male bonding may be partly responsible for pay discrepancies between men and women, says a new analysis. A National Bureau of Economic Research working paper suggests that the "male-to-male" advantage in promotions could be responsible for 39% of the gender pay gap, based on an examination of a multinational Asian bank. Male employees assigned to male managers were promoted faster than men assigned to female managers or women assigned to either gender manager, despite no observable difference in revenues or time worked, the report found.