Re: Are animals right brained or left brained like humans?

Dear Laurey,
 Thank you for your very interesting question. Brain asymmetry (the 
fact that the left hemisphere and the right hemisphere of the brain are 
not identical) and hemispheric lateralization of function (the fact that 
some mental processes occur more in one hemisphere than in the 
other) are fascinating topics!
 You say that humans are "left brained", and you are right to a large 
degree. As you know, the left hemisphere of the brain controls the 
right hand (and vice versa), and the fact that most humans are 
right-handed (90%) indicates that in most humans, the left brain is 
dominant. Another classic example of this is that in most humans, 
language is produced and understood by the left hemisphere. For a 
very good and very complete review of anatomic and functional 
differences between the right and the left hemisphere in humans, 
have a look at the brand new edition of Hellige’s book Hemispheric 
Asymmetry (2001).
 These issues have also been studied in animals (for a complete 
review, see Hiscock and Kinsbourne, 1995). Hand (or should I say 
paw!) preference, for example, is easy to evaluate in animals and  
has been studied in many species. Monkeys, cats and mice all show 
consistent preference for one of their paws. There is, however, an 
important difference: approximately 50% of monkeys, cats and mice 
show a preference for the right paw and about 50% show a 
preference for the left paw (Springer and Deutsch, 1989).  
 Language is more difficult to test in animals, but one study in 
Japanese macaque monkeys shows that they also seem to 
understand "language" (the vocalizations made by other monkeys) 
better with their left hemisphere (Petersen et al., 1978). 
 A classic study in songbirds shows that their "language" (song) 
production is dependent upon the left hemisphere (Nottebohm, 
1977). The organ of song production of canaries and chaffinches is 
called the syrinx. The two small hemispheres of the bird’s brain are 
connected independently to the syrinx, by two nerves called the (left 
and right) hypoglossus. Cutting the right hypoglossus has very little 
effect on bird song, but cutting the left hypoglossus replaces the song 
by either poorly modulated sounds or complete silence! 
 In conclusion, I think it is safe to say that animals are not "right 
brained". These last two studies in monkeys and birds even seem to 
indicate that,  at least for language, they are "left brained like 
humans". 
 The left-brain, right-brain distinction is interesting, but remember that 
handedness and language are extreme examples of hemispheric 
lateralization of functions. Both in humans and animals, the brain 
works at its best when both hemispheres are intact and able to 
communicate! 
 I hope this answers your question. Cheers!
 Benoit


References:

Hellige (2001) Hemispheric Assymetry. Cambridge: Harvard 
     University Press.
Hiscock and Kinsbourne (1995) in Brain Asymetry (Davidson and    
     Hugdahl Eds.).  Cambridge: the MIT Press
Nottebohm (1977) in Lateralization of the Nervous System (Harnad et 
     al. Eds). New York: Academic Press.
Petersen et al. (1978) Science 202, 324-326.
Springer and Deutsch (1989) Left Brain, Right Brain. New York: 
     Freeman and Co.