system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do humans and many animals have a dominant hand?
gpt
We don't exactly know. We don't even know what brain structures correspond to handedness, it's very controversial right now. Your brain does something called lateralisation. It means that the left side and the right side are sort of different. The reason for this is because your brain only has a certain amount of space. If you dedicate only one hand to doing complex movements, you can use that space on the other side of the brain for something else. It's 'inefficient' to have both hands being able to do complex tasks well because there's few situations where you need to. So by only having one hand be able to do those, you save space. The other hand is used for holding things, or positioning them so you can use your dominant hand for complex manipulations.