Matthews found a German study which looked at what he called "mixed-handedness", that is, the capacity to use both left and right hands equally. It looked at mixed-handedness in 40 musicians on a variety of instruments. Researchers examined a number of variables, for example, type of instrument played, regularity of practice undertaken and length of time playing instrument, and found the following, keyboard players had high levels of mixed-handedness, whereas string players like cellists and violinists strongly favoured one hand. Also those who started younger were more mixed-handed. Matthews also reports studies of handedness in apes. Apes get a large proportion of their food by "fishing" ants from ant hills. The studies show that apes, like humans, show handedness, though for them right and left-handedness is about equal, whereas about 85% of humans are right-handed. Studies showed that apes consistently using the same hand fished out 30% more ants than those varying between the two.