David and Goliath

Many of you are familiar with the famous story of David and Goliath, which appears in the Hebrew scriptures (Old Testament). The armies of the Philistines and the Israelites were gathered for battle when Goliath, a Philistine, came forth and challenged the Israelites to settle the dispute by sending out their best man to face him in a fight to the death. Goliath, it seems, was a man of great proportions, measuring over "six cubits" in height. If you consider that a cubit is the distance from the elbow to the tip of the middle finger, about 20 inches, this guy was over 10 feet tall! Goliath was armed to the teeth with body armor, a javelin, and a sword. To face this giant, the Israelites sent David, a young and diminutive shepherd, armed only with a sling and five smooth stones. Here's how the action is described in the Revised Standard Version of the Bible (1 Samuel 17:48)

When the Philistine arose and came and drew near to meet David, David ran quickly toward the battle line to meet the Philistine. And David put his hand in his bag and took out a stone, and slung it, and struck the Philistine on his forehead; the stone sank into his forehead, and he fell on his face to the ground.

Now why, you might ask, are we giving a theology lesson in a neuroscience textbook? The answer is that our understanding of the visual pathway offers an explanation, in addition to divine intervention, for why Goliath was at a disadvantage in this battle. Body size is regulated by the secretion of growth hormone from the anterior lobe of the pituitary gland. In some cases, the anterior lobe becomes hypertrophied (swollen) and produces excessive amounts of the hormone, resulting in body growth to unusually large proportions. Such individuals are called pituitary giants and can measure well over 8 feet tall. Pituitary hypertrophy also disrupts normal vision. Recall that the optic nerve fibers from the nasal retinas cross in the optic chiasm, which butts up against the stalk of the pituitary. Any enlargement of the pituitary compresses these crossing fibers and results in a loss of peripheral vision called bitemporal hemianopia, or tunnel vision. (See if you can figure out why this is so from what you know about the visual pathway.) We can speculate that David was able to draw close and smite Goliath because, when David raced to the battle line, the pituitary giant had completely lost sight of him!

Taken from Page 243 and 247 of

Bear MF, Connors BW, and Paradiso MA. Neuroscience: Exploring the Brain: Williams & Wilkins; Baltimore: 1996.