Where there is reference to the brain of animals in
discussions of their complexity, there has sometimes
been an assumption that nearness in structure to
humans is the best estimate of sophistication. However, such estimates should take account of function
rather than anatomy alone, because animals vary in
the parts of the brain that have complex analytical
functions. Although some mammals have high level
analysis functions in the cerebral cortex, a comparable
high level of analysis occurs in areas of the striatum in
birds and in a variety of brain regions in fish and
cephalopods. We may also over-emphasise visual analysis, even though other senses have a more primary
role in the lives of many mammals, fish and invertebrates. For example, the world of many mammals is
much more olfactory than visual, and that of some fish
is centred around lateral-line organs that measure
localised pressure changes or electro-receptors monitoring changes in patterns in the surrounding electrical
field. If we are evaluating extent of awareness in
animals or attempting to ensure that their welfare is
good, we should take account of the world as they
perceive it.