Men with deep voices tend to have more children than men with high voices, American scientists have found.

They spent six months studying a tribe in Africa.

Males with a deep voice had an average of two more children than those men in the tribe with higher voices.
 
Deep (adjective) :bottomless    عمیق
 ‌
Tend (verb): be likely   متمایل بودن به
 
Tribe (noun): family  قبیله، طایفه
 
Average )  adjective) : common, intermediate