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As humans grew more proficient with visual and vocal systems, the evolutionary pressure to move their ears ceased. This caused the auricular muscles to become vestigial, scientists thought.
The muscles connected to the ears of a human do not develop enough to have the same mobility allowed to monkeys. Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through evolution. Although ...
The postauricular reflex is a vestigial myogenic [5] muscle response in humans that acts to pull the ear upward and backward. [6] Research suggests neural circuits for auricle orienting have survived in a vestigial state for over 25 million years. It is often assumed the reflex is a vestigial Preyer reflex (also known as the pinna reflex). [7] [8]
Other structures that are vestigial include the plica semilunaris on the inside corner of the eye (a remnant of the nictitating membrane); [28] and (as seen at right) muscles in the ear. [29] Other organic structures (such as the occipitofrontalis muscle ) have lost their original functions (to keep the head from falling) but are still useful ...
A vestigial response or vestigial reflex in a species is a response that has lost its original function. In humans, vestigial responses include ear perking, goose bumps and the hypnic jerk . In humans
Some large primates such as gorillas and orangutans (and also humans) have undeveloped ear muscles that are non-functional vestigial structures, yet are still large enough to be easily identified. [77] An ear muscle that cannot move the ear, for whatever reason, has lost that biological function. This serves as evidence of homology between ...
Female rats wiggle their ears when they are in heat, to excite male rats and encourage them to mate. [4] Ear wiggling was a shtick in Hal Roach comedies such as Laurel and Hardy and Our Gang. To achieve this effect, performers such as Stan Laurel would have their ears pulled by threads which would not be visible in the film. [5]
The extrinsic auricular muscles are the three muscles surrounding the auricula or outer ear: anterior auricular muscle; superior auricular muscle; posterior auricular muscle; The superior muscle is the largest of the three, followed by the posterior and the anterior. In some mammals these muscles can adjust the direction of the pinna.