(no subject)
For dogs, wagging the tail may have developed over time as a way to spread the scent from the anal glands over a wide area during play, broadcasting the dog's identity to all other dogs in the areas. This is in contrast to the proven meaning of the submissive ducking the tail between the legs, which has the purpose of sealing off this important component of the dog's scent from the outside world. It is unknown if the fanning action of a wagging tail is indeed meant to act as a scent dispersal mechanism, seeing as to how the dominant-aggressive stiffened tail posture does not wag.
In addition, felines, who are known to also hold tails aloft when seeking identification, do not wag tails. However, the role of scent in feline communication may be different, or the wagging tail method may have developed as a social cortex mutation unique to the canid brain line.
Addendum: horse wagging tail: http://www.youtube.com/watch?v=jbm8Lm1i5yc
In addition, felines, who are known to also hold tails aloft when seeking identification, do not wag tails. However, the role of scent in feline communication may be different, or the wagging tail method may have developed as a social cortex mutation unique to the canid brain line.
Addendum: horse wagging tail: http://www.youtube.com/watch?v=jbm8Lm1i5yc