Home Page

Compare Brains

Compare Brain and Body Sizes

Compare Brain Structures- Slices and Slides

The Neuron- Up Close and Personal

The Question of Intelligence




What is the relationship between brain and body size??

Clearly different animals have differently sized brains. How important is brain size for behavior? Some people have thought that brain size is strongly related to intelligence. But, as you may have noticed, it also looks a bit like brain size may simply be bigger in bigger animals and smaller in smaller animals-- regardless of "intelligence".

On the next couple of pages will be a series of tables designed to help us visualize brain size in relation to body sizes and develop questions from that. The table below shows, on the left, brains whose apparent size is appropriate for the pictures on the right. Click on the pictures of the animals to read specific information about the species. Since the pictures on the right don't accurately show relative sizes of the animals, we can't conclude from this much about whether bigger animals have bigger brains.

human brain

approx Human brain length=15cm

approx brain weight=1400g

approx body length=100cm

approx body weight=62,000g

baboon brain

approx Baboon brain length= 8cm

approx brain weight=140g

approx body length=75cm

approx body weight=30,000g

monkey brain
approx Monkey brain length=5cm

approx brain weight=100g

approx body length=30cm

approx body weight=7,000g

camel brain
approx Camel brain length=15cm

approx brain weight=680g

approx body length=200cm

approx body weight=529,000g

dolphin brain
approx brain weight=1700g
approx body length=10 feet

approx body weight=160,000 g

kangaroo brain
approx Kangaroo brain length=5cm

approx brain weight=56g

approx body length=150cm

approx body weight=35,000g

cat brain
approx Cat brain length=5cm

approx brain weight=30g

approx body length=60cm

approx body weight=3,300g

raccoon brain
approx Raccoon brain length=5.5cm

approx brain weight=39g

approx body length=80cm

approx body weight=4,290g

rabbit brain
approx Rabbit brain length=5cm

approx brain weight=12g

approx body length=30cm

approx body weight=2500g

squirrel brain
approx Squirrel brain length=3cm

approx brain weight=6g

approx body length=20cm

approx body weight=900g

frog brain
approx Frog brain length=2cm

approx brain weight=0.1g

approx body length=10-12cm

approx body weight=18g

The actual sizes of the animals and brains are given in this this chart. But it may be easier to do some comparisons by changing the size of the pictures . . .

How do the brain sizes compare when the animal pictures are correctly in proportion?

Why should I care about this kind of comparison??

Huh? Can we start over?