in rate of finger tapping for each hand were measured during three con-
ditions:repeating a simple spoken phrase,singing a rote song with words,
and singing scales without words (Hough et al.1994).The degree to
which each condition caused departure from a baseline level of tapping
for each hand is believed to indicate the approximate extent to which
the opposite hemisphere (i.e.,the one controlling the hand) was involved
in each activity.As other studies concluded,speech and singing appeared
to be mediated primarily by left and right hemispheres,respectively,and
women were less lateralized than men for all three tasks.Of interest,
men were especially lateralized for singing with words;finger tapping
decreased noticeably for their right hands,indicating different involve-
ment of the left hemisphere (LH) for this task.The authors concluded
(Hough et al.1994:1074):Thus,the laterality differences in females appear to be driven by both hemi-
spheres whereas laterality differences in males are driven primarily by variation
in the involvement of the LH.This finding is in accordance with previous sug-
gestions that females are less lateralized or have more symmetrical representa-
tions than males.Clearly,the human brain is an extremely complicated and variable
organ.Nevertheless,studies using medical imaging technology help to
clarify certain details about the neurological substrates for processing
two interrelated endeavors that are specific to the human primate—lan-
guage and music.As shown,musical processing varies not only with train-
ing but with gender.The latter finding is significant for understanding not
only the origins of music but also for investigating human brain evolu-
tion in general.Brain Evolution and the Origins of Music
Models of the kinds of behaviors that must have preceded humanlike
music and language may be sought in other animals.For example,some
birds (Slater,this volume),whales (Payne,this volume),and gibbons
(Geissmann,this volume) sing without words,and at least some primates
(e.g.,vervet monkeys) have utterances that are part of “referential
emotive vocalization systems”(Brown,this volume) that vary systemat-
ically with certain stimuli (e.g., alarm calls for specific predators).
Because humans are evolutionarily closely related to gorillas and even
more so to chimpanzees,the auditory communication systems of these
African great apes are of particular interest to those pursuing the origins
of music,language,and singing with words (see Geissmann and Ujhelyi,
this volume).For example,male gorillas are likely to include a series of
hoots in their physical displays and,according to Schaller (1963),two or209 Hominid Brain Evolution and the Origins of Music