Well, I’ll be a monkey’s uncle! Although it was shocking at first, we now accept that other apes share 99% of our genes. However, what even makes an ape, are humans apes too? To tell the story of whether or not humans are apes, we need to venture on a linguistic journey. The meaning of the word “ape” has changed over time and has been used to describe different things. The reason for this change over time is the amount of knowledge that we have of other primates. Additionally, scientists use the word differently than you or I would in everyday use.

Historically, the word “ape” has been used to differentiate between humans and, well, other primates. After the word “monkey” was introduced into the English language, it was either used as a synonym to “ape” (according to a 1910 Encyclopaedia Britannica entry) or to specifically name primates without tails. Some monkeys even have the word “ape” in their name, such as the Barbary ape. In everyday usage, the two words are often used interchangeably.

Barbary apes are actually not apes, but monkeys. Image credits: Pixabay.

In the first half of the 20th century and before, primates were arranged in a grade from least advanced to humans. Monkeys were considered less advanced than apes and were distinguished this way. In the 1940s, some scientists, such as Frederic Wood Jones, challenged this idea that complexity simply increased from lemurs to monkeys to apes to humans. He believed that primate relationships are complex and marked by parallel evolution. He, along with other researchers, started establishing the relationships between the different primates.

The grade from “more primitive” to “advanced”. Image credits: Ernst Haeckel.

The tree of life

When scientists started putting together the tree of life, humans and “apes” were completely separate groups. Chimpanzees, gorillas, orangutans, and gibbons were considered to be in one group, and humans in a separate group.

The old views of the relationships in Hominoidea— humans (Homo) are very separate from the other groups. Image credits: Rursus.

In the past 50 years, scientists learned more about the relationships between the species with molecular studies. They found that gibbons form a separate group, but that humans are very closely related to chimpanzees and gorillas. When humans were considered very different, the term “ape” was used to describe this group of other primates that we were different from. But now that we know that we’re very similar and actually part of the same grouping, this old definition doesn’t work so well. If you say “Oh, just chimps, gorillas, gibbons, and orangutans are apes” then you are creating an artificial group, because humans should be part of this group by their relatedness.

The relationships in Hominoidea to the best of our knowledge. Image credits: Rursus.

Biologists don’t like groups that only include a few of its members because they aren’t very informative or representative. They instead use monophyletic groups that include all of the descendants of a common ancestor. “Ape” now becomes another word for Hominoid, the all-encompassing group that includes humans, gorillas, chimps, orangutans, and gibbons. Within this group, humans are included with the rest of the great apes. The term “great apes” specifically includes humans too. Scientists distinguish between humans by calling them Hominin and others as “non-human apes”.

The yellow group (monophyletic) is most informative. The blue group (paraphyletic) is the type of group that “apes” would be if humans weren’t included— not so informative and complete. Image credits: Petter Bøckman, revised by Peter Brown

Many opinions

However, there is still a great deal of disagreement, even in the scientific community, about whether humans are considered apes. Many, as previously mentioned, consider this whole Hominoid group as apes. Some people use the historical definition, to describe non-human primates. Indeed, this is the most common in everyday usage. The Merriam-Webster dictionary defines an ape as “any of various large tailless semi-erect primates of Africa and southeastern Asia (such as the chimpanzee, gorilla, orangutan, or gibbon)”. Some researchers argue that we are not apes but ex-apes because we are fundamentally different from other apes. These differences are due to the way we communicate and other things that are not visible just by looking at DNA. In this case, the word “ape” means something different than Hominoid. Anyhow, the usage of the word depends on how you interpret the word, because it is still being used differently by different people.

Are apes so different from us? Image credits: CBS Television Network

Unfortunately, there isn’t a straightforward answer to the question of whether humans are apes or not. The most common consensus is that non-human primates are considered apes and humans are Hominoid. Anyways, we’re still primates, and closely related to chimps, whether we are “apes” or not.

 

 

 

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