Inside of a Dog_ What Dogs See, Smell, and Know - Alexandra Horowitz [45]
The isolation barks tended to be higher-frequency and more variable: some ranged from loud to soft and back again, some went from high to low. These barks are lobbed into the air one by one, sometimes with great intervals between them. They sound "fearful," people tend to say.
Play barks, too, are high-frequency, but they happen more often one after the other than the isolation barks. They're directed at someone else, unlike isolation barks: at a dog or human playmate. There is considerable individual variation, of course: not every dog barks alike. The stranger bark of a small dog may come out as rar, rar or raoaw, raoaw, while a larger dog emits a capital-r Rumph.
These differences between bark types make evolutionary sense: the lowest sounds are used in threatening situations (again to appear bigger); higher sounds are entreaties—to friends, for companionship—and as such are submissive requests, not warnings. Differences between individual barkers indicate that barks might be used to affirm a dog's identity, or reveal an association with a group (even the group me and the woman at the end of my leash, rather than these dogs I'm frolicking among). And barking together with others may be a form of social cohesion. Barking can be contagious, like the howl: one dog barking might prompt a chorus of barking dogs, all joined in their shared noisiness.
BODY AND TAIL
When we approached people on the street, Pump set all her senses to looking; if she recognized them, her head would lower ever so slightly—looking up coyly as though over reading glasses—and she would wag her tail low. This was quite different from her approach of a dog she was smitten with: all upright, tail high, posture impeccable, wags soldierlike in their rhythm—or a dog friend—a looser,
janglier approach, and even an open-mouthed grab toward their face, or a gentle bump with her hip along their body.
You may be sitting down right now, folded into a comfy chair—or perhaps you're standing, straphanging on a train to work, book scrunched against another commuter's back. Most likely you don't mean anything by your sitting or standing, or when you walk or lie supine: it's just a posture of convenience or comfort. But in other contexts our very posture conveys information. A catcher crouches: he's prepared for a pitch. A parent crouches and opens his arms: he's inviting a child for a hug. Running when someone you know approaches, you suddenly stop and greet them; standing still when someone you know approaches, you suddenly turn and run. There can be meaning simply in the vigor or slouch of your body. For an animal with a limited vocal repertoire, posture is ever more important. And it appears that dogs use specific postures to make very specific statements.
There is a language of the body, formed of phonemes made from rumps, heads, ears, legs, and tails. Dogs know how to translate this language intuitively; I learned it after watching hundreds of hours of dogs interacting with each other. We must look like such stiffs to dogs, who can express everything from playfulness to aggression to amorous intent by changing the shape of their body and its altitude. By contrast, we are inhibited straight-backeds, mostly stationary or traveling forward with little excess movement. Occasionally—heavens—we turn a head or arm flamboyantly to the side.
But man himself cannot express love and humility by external signs, so plainly as does a dog, when with drooping ears, hanging lips, flexuous body, and wagging tail, he meets his beloved master.—Charles Darwin
For dogs, posture can announce aggressive intent or shrinking modesty. To simply stand erect, at full height, with head and ears up, is to announce readiness to engage, and perhaps to be the prime mover in the engagement. Even the hair between the shoulders or at the rump—the hackles—may be standing at attention, serving not just as a visual signal of arousal but also releasing the odor of the skin glands