Puppy?

April 30th, 2022| Topic: RaMbLeS | 0

Dog faces have apparently evolved over tens of thousands of years. Well, what’s so strange about that, you ask?

Here’s the answer from scientists from the University of Portsmouth, UK, and from Howard University, NC State, and Duquesne in the US. In “Evolution of Facial Muscle Anatomy in Dogs,” published in the Proceedings of the National Academy of Sciences.

Dogs were shaped during the course of domestication both in their behavior and in their anatomical features. Here we show that domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans. A muscle responsible for raising the inner eyebrow intensely is uniformly present in dogs but not in wolves. Behavioral data show that dogs also produce the eyebrow movement significantly more often and with higher intensity than wolves do, with highest-intensity movements produced exclusively by dogs. Interestingly, this movement increases paedomorphism and resembles an expression humans produce when sad, so its production in dogs may trigger a nurturing response. We hypothesize that dogs’ expressive eyebrows are the result of selection based on humans’ preferences.”

How about that—dogs have developed a muscle above their eyes that they use to make their eyes look larger and create that endearing “puppy dog eyes” expression! That is to say, faces of dogs evolved to make them more appealing to humans!

Humans domesticated dogs with attention to the facial expressions that dogs produce, selecting for a suite of facial movement. Domestic dogs and humans are adept at accurately understanding one another’s facial expressions and movement around the eyes in dogs is highly valued by humans. This unique, mutual ability to accurately process facial expressions is part of the dog-human bond. An accurate understanding of how dog and wolf faces differ from one another is fundamental to understanding the processes of animal domestication, evolution of the dog, and the origins of human behavior.”

In fact, comparing facial muscles of dogs with those of wolves, it was shown that the facial muscles of dogs have a much higher proportion (66–95%) of “fast-twitch” muscle fibers—that are involved in facial expression—than do wolves (25%). And this, it seems, lets dogs more effectively communicate their feelings to their owners (or manipulate them)!

Said senior scientist in the group, Dr. Anne Burrows, of Duquesne:

It’s quite a remarkable difference between dogs and wolves. They just don’t move their faces in the same way.”

She thinks this could be a consequence of the process of domesticating dogs by picking and selecting puppies that seemed most responsive to humans, resulting in dog faces becoming “faster” over time.

On the other hand, the facial muscles of domesticated horses and cats don’t show the same changes from wild horses and wild cats, compared to the changes between dogs and wolves.

But we, not dogs, have a face we can look to and be assured of help in time of need, without needing to evolve any extra fast-twitch muscles to elicit that Helper’s grace.

My eyes are constantly toward Yahweh,
for He—He brings forth my feet from the net.
Face towards me and be gracious to me,
for alone and afflicted I am.
The distresses of my heart are increased;
from my straits bring me out.
Look upon my affliction and my trouble,
and forgive all my sins.
Look upon my enemies, for they are many,
and with violent hatred they hate me.
Guard my soul and rescue me;
may I not be ashamed, for I seek refuge in You.
May integrity and uprightness preserve me,
for I wait for You.
Psalm 25:15–21

SOURCE:
PNAS; Experimental Biology; NBC News