Duba wurin da ke ƙasa sannan ka amsa tambayar daga baya a cikin harshe ɗaya kamar yadda wurin yake:  Passage: A cikin littafinsa Dama-Hand, Hagu-Hand, Chris McManus na Jami'ar Kwalejin London ya yi jayayya cewa yawan masu amfani da hagu yana ƙaruwa kuma masu amfani da hagu a matsayin rukuni sun samar da ƙididdigar sama da matsakaici na manyan masu nasara. Ya ce kwakwalwar 'yan hagu suna da tsari daban-daban (ta hanyar da ke kara yawan damar su) kuma kwayoyin halittar da ke tantance hagu-hannun ma suna sarrafa ci gaban cibiyoyin harshe na kwakwalwa.Rubuta a cikin Scientific American, McManus ya bayyana cewa,  Tambaya: Menene Chris McManus ya ce game da mutanen da ke amfani da hannun hagu?
yawan masu amfani da hannun hagu yana ƙaruwa