ELi5: Why do small animals (birds, squirrels, etc.) have such “faster reflexes” than humans?

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I understand they are smaller and can move faster than humans, but why can they wait so long before moving?

For instance, when you’re driving and a bird is able to wait until the absolutely last second before flying away and avoiding getting hit. What allows animals to have such better reflexes?

In: Biology

7 Answers

Anonymous 0 Comments

Muscles come in two big varieties: fast-twitch and slow-twitch.

Fast twitch muscles react quickly, but tire easily. Your housecat is a great example of an animal with lots of fast-twitch muscles. Their physiology is designed for waiting for prey, then pouncing on it before it knows what’s happening. If you’ve ever had a heavy play session with a cat though, you’ll notice they start panting and get tired *quick*.

Humans are endurance hunters. We are basically the Terminators of the animal kingdom. We can run for miles chasing prey seemingly unphased until the prey gets tired. See this [BBC Earth video](https://www.youtube.com/watch?v=826HMLoiE_o). We have slow-twitch muscles that react slowly, but can go on *forever* from the perspective of a cat, antelope, or deer.

So, why do these animals seem to move quicker? Because they are prey and need to be able to boogie when the time comes, hopefully outrunning their predators by outlasting them (antelope vs cheetah) or just getting away quicker to the point they give up (antelope vs human)

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