Dogs
Rolling in something foul is scent camouflage
The instinct comes from wild canids masking their own smell or carrying news of a carcass back to the pack. Your dog is not being rude, just very old-fashioned.
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A dog's yawn is often stress, not sleepiness
Dogs yawn to defuse tension. If your dog yawns while being hugged or scolded, it is asking for space, not a nap. Give it a moment and the body language relaxes.
The slow blink and head turn means 'I'm no threat'
Turning the head away, licking lips and sniffing the ground are calming signals. Dogs use them to keep the peace, and you can mirror them to settle a nervous dog.
A wagging tail does not always mean happy
Research shows wags biased to the right signal comfort and to the left signal unease. A high, stiff, fast wag is arousal, and can tip into a bite.
Sniffing tires a dog more than running
Twenty minutes of free sniffing on a walk drains more mental energy than an hour of fetch. Let the leash go slack and let the nose lead for a calmer evening.
Dogs read your face better than chimps do
Domestication tuned dogs to human expressions and pointing gestures. They check your eyes for permission before taking food, something wolves never do.
Puppies have a socialisation window that closes at 16 weeks
Sights, sounds and people met before then feel normal for life. Gentle exposure in that window prevents most adult fear problems.