Which Other Primates Besides Humans Do Not Have Tails?

The question of which primates besides humans do not have tails is an intriguing one, particularly when discussing the characteristics that distinguish apes from other primates. Let's explore this topic in detail.

The Apes: Tailless Primates

Apes, a group of primates that includes humans, are known for their lack of tail. This characteristic distinguishes them from their primate cousins, the monkeys. Apes belong to the family Pongidae and include species such as baboons, bonobos, chimpanzees, gibbons, gorillas, and orangutans. Notably, none of these species possess external tails.

Internal Tail Remnants

While apes lack external tails, they do have an internal vestige of a prehensile tail. In humans, this vestige is often referred to as the coccyx or tailbone. This feature is a distinguishing characteristic that sets apes apart from monkeys, who typically have longer, visible tails.

Barbary Macaques: Tailless Monkeys

Barbary macaques, found on the Rock of Gibraltar, are often mistaken for apes due to their lack of a visible tail. However, these macaques are actually a species of Old World monkey. Some species of macaques, particularly those found in Africa and parts of Asia, do not have visible tails. Even in cases where they do have tails, they are notably shorter compared to other monkeys.

Another species of macaque, the kind found in Morocco, shares this trait. These macaques, while part of the monkey family, do not exhibit the characteristic long and prehensile tails typically associated with their relatives.

The Lesser Apes and Great Apes

When discussing primates, it's essential to differentiate between the lesser apes and the great apes. Lesser apes include gibbons and siamangs, while great apes include orangutans, gorillas, humans, chimpanzees, and bonobos. Both of these groups do not possess external tails, although they do have an internal tailbone as seen in humans.

About 25 million years ago, during a period when the ape lineage diverged from the monkey lineage, a genetic mutation occurred. This mutation essentially blocked the instructions for tail development, much like a flat-pack furniture kit where all the parts are there, but the instructions are missing.

Cerci: Tail-Like Appendages in Insects

It's important to highlight that not all tail-like structures are true tails. For instance, insects generally do not have tails, and some have structures called cerci. Cerci are sensory appendages located at the posterior end of the abdomen and are used primarily for detecting movement and contact. These are not true tails but serve similar functions in terms of sensory input.

Conclusion

In summary, while many primates have external tails, apes, including humans, do not. This characteristic is one of the most noticeable differences between apes and monkeys, and it serves as a fundamental distinction in the primate world. Understanding these differences helps us gain insight into the evolutionary history and characteristics of primates.