Why don't wild animals have floppy ears?

(Dan Tri Newspaper) - The soft, droopy ears of domestic dogs, cats, or rabbits are a familiar sight, but very rarely seen in the wild.

Folded ears, a curled tail, or mottled fur are considered "identifying features" of pets.

In nature, these characteristics are almost nonexistent.

The reason is simple: drooping ears are the result of a mutation that causes underdeveloped cartilage, limiting the ability to rotate the ear, locate sounds, and detect predators.

Such individuals have difficulty surviving and are quickly eliminated. That is why wild animals have developed large, erect ears that can rotate 360 ​​degrees to hear, react, and survive in a dangerous environment.

However, the story becomes more interesting when science realizes that floppy ears are not just the loss of a useful feature, but also a trace of a new evolutionary process – domestication.

A shocking experiment

In 1959, geneticist Dmitry Belyayev launched one of the most daring experiments of the 20th century: domesticating silver foxes by selecting only the docile individuals for breeding.

The floppy ears are a characteristic feature of many dog ​​breeds (Photo: Getty).

What surprised the scientists was that after only a few generations, the first foxes began to show less fear of humans. By the 20th generation (equivalent to 25 years), the research team had created a line of foxes that behaved like pets: wagging their tails, enjoying cuddling, and following humans around.

But what's even more surprising is their appearance. Along with their docile nature, domesticated foxes gradually develop short snouts, small teeth, changing fur color, curved tails, and, most notably, drooping ears. These are changes never seen in wild foxes.

This phenomenon coincides with Charles Darwin's observation of the "domestication syndrome".

A set of characteristics is repeated in most animal species domesticated by humans: smaller brains, mottled fur, curved tails, short faces, folded ears, and juvenile-like behavior.

But the biggest question remains: why does selectively choosing a gentle personality lead to changes in the body?

The explanation from the embryo: The role of the neural crest.

For many years, scientists leaned toward the hypothesis that genes controlling personality and appearance are closely linked. However, this model requires a genetic network so complex it seems impractical.

A more compelling explanation emerged when researchers traced back to embryonic origins: the neural crest. This is a group of cells that form early in the embryo, creating ear cartilage, skin pigmentation, the peripheral nervous system, and the adrenal glands, the organs that control the fear response.

If, during the selection process, humans prioritize individuals with less panic reaction, they may inadvertently select individuals with slight impairments in neural crest development.

These changes also affect the ear cartilage, coat color, and bone structure, leading to drooping ears, a curled tail, and other characteristics.

In other words, by simply activating a small "switch" in the embryo, a whole host of accompanying traits will appear simultaneously.

In 2023, two ecologists, Ben Thomas Gleeson and Laura Wilson, proposed a different perspective. They argued that changes in domesticated animals are not necessarily the result of personality selection, but may be a consequence of wild traits no longer being maintained.

In nature, erect ears offer a vital survival advantage: hearing from a distance, independent rotation, and faster escape.

However, in environments where humans live, free from the worries of predation, food scarcity, or reproductive competition, these pressures disappear. Consequently, the mutations leading to floppy ears are no longer detrimental, so nature no longer "eliminates" them. Gradually, the new trait becomes more common.

Evidence shows that even when selection is geared toward aggression, some characteristics of the "domestication syndrome" still appear. This indicates that the process is not simple, but rather a complex interaction between genetics, environment, and evolution.

Source: https://dantri.com.vn/khoa-hoc/vi-sao-dong-vat-hoang-da-khong-co-doi-tai-cup-20251212065633336.htm