Are apes monkeys?

Yes, apes are monkeys and therefore so are we. I’ve said it before and I’ve given my reasons, other biology types have said it and given their reasons, yet a crime against pedantry rages unabated.

There are some important questions in life and this probably isn’t one of them, but it seems to have generated a lot of debate, so it’s clearly a topic that needs resolution.

Why wouldn’t apes be monkeys?

If apes are indeed monkeys as I suggest, why do so many intelligent and knowledgeable people insist that apes are not monkeys? I think that perhaps it’s because apes didn’t used to be monkeys.

Let me explain. Taxonomy is the science of naming things and it was established as a discipline by Carl Linnaeus in the mid 1700’s. Evolutionary theory was not part of science at the time, so there was no real understanding of why species formed recognisable groups with shared common features – but those shared features proved useful for classification.

Linnaeus – and the taxonomists that followed in his footsteps – went about classifying things based on the presence or absence of physical and behavioural characteristics.

Defining apes and monkeys

According to the Linnaean system of classification monkeys were medium or small in size and had tails, whereas apes were medium to large in size and didn’t have tails. Simple, apes were not monkeys – except the Barbary Ape Macaca sylvanus (Linnaeus, 1758), which was quite obviously a monkey despite being medium-sized and having no tail… spot the problem?

Phylogenetic systematics

In the 1950’s a taxonomist called Willi Hennig had the bright idea of applying an understanding of evolutionary relationships to taxonomic classifications – he called this phylogenetic systematics. It was an idea that made sense, because rather than basing groups on arbitrary characters that might be open to convergent evolution (like becoming tailless), species could be grouped together (in something called a ‘clade’) according to common ancestry. What a nifty idea!

However, this idea has taken time to get established, since identifying clades means compiling and analysing a huge amount of data. It wasn’t until computers became capable of taking on some of the workload that phylogenetic systematics (or cladistics) became properly established – in real terms this meant that progress was slow until the mid-to-late 1990s.

Since cladistics has taken off, there has been an effort to marry Linnean classification terms with evolutionary classifications where possible, to limit the confusion caused when discussing groups of organisms. There are rules in the form of PhyloCode, but they don’t really address common names associated with clades.

As a result this revolution in taxonomy has been largely ignored by the public and indeed by scientists not involved in the process. Nonetheless, it directly impacts on how biological terms are used. In this instance the issue impacts on whether apes should be considered monkeys – the fact that they share a clade, suggests that they should.

But is monkey a valid term?

Neither ‘monkey’ nor ‘ape’ are proper scientific terms, but both are commonly used in scientific literature, so they should have formal recognition as valid biological terms. That means that they should be aligned with definable clades, since that’s how taxonomy is done these days. In this case the Simiiformes clade for monkeys and Hominoidea for apes.

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Common usage of biological terminology may be slow to follow the science, but if it wasn’t related to taxonomy we’d still be calling whales ‘fish’ (which is a fascinating story in its own right). Certainly there would be no justification for denying that apes were monkeys if people were not referring back to traditional taxonomy, because the term would be defined by usage alone and people do call apes monkeys.

In fact, it’s only seems to be in English that a distinction is made between apes and monkeys in common terminology and even then the terms have long been used interchangeably.

Of course a hard-liner can argue that we should just ditch the terms monkey and ape and stick with proper scientific terminology. I agree with the logic from a scientific perspective, but culturally it would be a bit much to expect the public to toe the scientific hard-line.

If the term monkey is to remain, it should at least be meaningful, which requires the cladistic definition and the inclusion of apes. As explained in more detail in the video below [NB contains swearing]

Should apes be called monkeys?

Let’s face it, it doesn’t really matter if apes are called monkeys.

Monkey is a more generic term than ape, which means it’s not very accurate or meaningful when talking about apes. Therefore it’s not really very appropriate unless the person using the term has a limited ability to identify very characteristic primates.

These are good reasons for not using the term monkey when referring to an ape, but nonetheless an ape is still a monkey. So feel free to criticise the use of monkey when referring to a Chimpanzee (for example), but don’t do it by saying that Chimps aren’t monkeys, because you’d be the one who is wrong – at least from a cladistic perspective.

I don’t know about you, but I’m getting tired of monkeying around the topic.