Now that you have seen these brains, ask yourself the following
- What are the similarities and differences between the brains?
- What are their relative sizes?
- Identify areas of the brain. Cortex? Cerebellum?
- Are their noticeable differences in any particular parts of the
- Is the cortex smooth or rough?
- Compare the placement of the cerebellum and spinal cord.
- Compare the size of the olfactory bulb.
- Compare the size of the cerebral cortex.
- Discuss brain weight vs body weight issues.
- Discuss brain size and intelligence.
- Discuss language and brain size.
- Discuss cortical expansion in higher species.
(Images with the permission of Dr.
Wally Welker of the Mammalian Brain
the University of Wisconsin)
The total surface area of the human cerebral
cortex is about 2,500 cm2. This is about the size of a pillow
case (about 40 cm by 62.5 cm). How do the surface areas of the cortex
from other animals compare? Below are the SURFACE AREAS of various
brains. Your job is to calculate the dimensions (into a square or
rectangle or circle) of these surface areas and to draw them on a piece of
paper. After you see the size of each brain, you should think of a
"common object" (such as a postage stamp or a piece of notebook paper)
that fits the dimensions. For example, if a surface area is 400
cm2, you can draw a square that is 20 cm by 20 cm (=400
cm2) and see its actual size (a little more than half a sheet
of notebook paper).
Total surface area of the cerebral cortex (human) = 2,500
Total surface area of the cerebral cortex (lesser shrew) = 0.8
Total surface area of the cerebral cortex (rat) = 6 cm2
Total surface area of the cerebral cortex (cat) = 83 cm2
Total surface area of the cerebral cortex (African elephant) = 6,300
Total surface area of the cerebral cortex (Bottlenosed dolphin) = 3,745
Total surface area of the cerebral cortex (pilot whale) = 5,800
Total surface area of the cerebral cortex (false killer whale) = 7,400
(References for these surface area figures: Nieuwenhuys, R., Ten
Donkelaar, H.J. and Nicholson, C., The Central Nervous System of
Vertebrates, Vol. 3, Berlin: Springer, 1998; A. Peters, and E.G.
Jones, Cerebral Cortex, 1984; S.H. Ridgway, The Cetacean
Central Nervous System, p. 221)