An easily made melee weapon that can also be thrown. Has a chance to break when used.
— In-game Description

The Spear is the first main weapon in the game, it is best used as a throwing weapon because it can break after a little as one hit when used in melee. Thrown spears can be recovered from the ground or from a corpse.

Using spears to harvest meat will give you a higher chance of recovering prime meat from a dinosaur than using any other stone tool.