Differences Between Human & Sheep Brain

Behind that glassy stare lies a surprisingly human-like brain.

Biology students often dissect sheep brains in order to understand the composition of the human brain. All mammalian brains are similar, and sheep brains serve as useful and readily available instruction tools. However, there are a few noticeable differences between sheep and human brains.

Size and shape

Human brains are larger. An adult human brain typically weighs 1,300 to 1,400 grams and measures 15cm across, while an adult sheep brain is 140 grams and is roughly one third as long. Sheep brains are elongated, and the brain stem is directed outward towards the animal's horizontal backbone. Human brains are more rounded, and the brain stem is directed downwards towards the vertical backbone.

Contours

Human brains have considerably more ridges and contours (convolutions and sulci) than sheep brains, giving them a much larger surface area than is readily apparent.

Cerebellum

The human cerebellum (which controls complex motor control and behavior) is proportionately much bigger than a sheep's cerebellum.

Olfactory bulb

Sheep brains have comparatively larger olfactory bulbs, which control the sense of smell. Like most animals, sheep rely on their ability to smell more than humans do.

Pineal Gland

The pineal gland (which controls basic instinctual behaviors such as circadian rhythms and seasonal reproduction) is more pronounced in the sheep's brain than in the human's.

References

• Laboratory Exercise 30: Dissection of the Sheep Brain
• Sheep Brain Dissection: The Anatomy of Memory
• Brain Facts and Figures