Vestigial structures

Trought evolution individuals might lose function in some structures, tissues and organs that they do not need to use, yet they might not disappear completely and that's what we call vestigial structures.

The truth is that even in their main function diminished these structures can continue to perform some secondary tasks and we can recognize their role in other species related by common ancestry

Important concepts so far:

• Vestigial structure: Genetically defined features or traits that have lost most or all their ancestral function.

• Adaptation: A change to something or its parts that makes it more suitable for survival in its current environment.

Exemples for vestigial structures

Snakes:

They present pelvic bones but they dont have legs, yes thats right. Since they are descended from reptiles that did have legs.

Whales:

Whales present traces of pelvic bones with no legs. In male whales, the pelvis controls the penis with an especially elaborate set of muscles.

Human:

In humans, for example, the appendix is a hollow-ended tube linked to the cecum of the large intestine that does not actively engage in digesting. Some theories imply that it may protect gut flora or have a role in the lymphatic and immunological systems, while its precise purpose is unknown. Previously, wisdom teeth were utilized to aid in the grinding and chewing of plant tissue. As humans used fire to cook and soften food, wisdom teeth became obsolete, and a smaller jaw with fewer teeth grew more popular over time.

We also have goosebumps and coccyx (tail bone) that despite having some secondary functions they are diferente from the rest of the animals who also present them.

The plica semilunaris, a tiny fold of tissue on the inside corner of the eye that aids in tear drainage and debris cleansing, is another example of a vestigial structure in the human body. It is a vestige of the nictitating membrane, or third eyelid, which is seen in other animals such as fish, amphibians, reptiles, and birds.

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References:

1. Vestigial Structures: What Are They, Examples, and More | Osmosis. (2021). Osmosis. https://www.osmosis.org/answers/vestigial-structures

2. 18.5H: Vestigial Structures. (2018, July 13). Biology LibreTexts. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/18%3A_Evolution_and_the_Origin_of_Species/18.05%3A_Evidence_of_Evolution/18.5H%3A_Vestigial_Structures

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