Dogs have been humans’ best friends for tens of thousands of years, but we still have a hard time decoding their behavior.

But dogs are highly social animals that communicate quite clearly through their bodies, ears, tails, eyes, and behaviors, the Wall Street Journal reports.

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You just have to know what to look for. Here are a few signs:

Ears, tails: A relaxed dog will have his or her ears up and tail down. An alert dog’s tail will be straight out, ears forward. A tucked tail reveals fear.

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Will the dog bite? If a dog’s hackles (the hairs along the back of the neck) are raised and the nose is wrinkled, he or she may just bite if pressed further.

That wagging tail: A dog whose tail is stiff and wagging slowly (or not all wagging) may be agitated. If the dog’s ears are forward and eyes are dilated, an attack may be imminent.