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?
Of course I’m an ape – look, no tail – Barbary Macaque CORRECTION Crested Black Macaque (Macaca nigra) aka the Sulawesi Black Ape – Thanks Prancing Papio
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.
Computers running cladistic analyses can tell us if apes are monkeys.
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.
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.
Zygoma 
Your “Barbary Macaque” picture is actually a Crested Black Macaque (Macaca nigra).
Thanks for that – I had my doubts since there are several Macaques with vestigial tails, but I’m not great on primate identification, especially when the skin is still on!
We have spell-checkers, grammar-checkers, but no idiom-checkers; it should be “TOE the…line.” (http://en.wikipedia.org/wiki/Toe_the_line).
Meanwhile, back on topic. If we removed just the Old World Monkeys, would it sill be valid to refer to Apes as Monkeys? By that logic, Apes would also be Tarsiers.
If the Old World Monkeys were removed the New World Monkeys could form a clade on their own, as could the Apes and the Tarsiers.
There is a clade including the Tarsiers and all monkeys (the Haplorrhini) but since only the Tarsiers are commonly called Tarsiers within the clade there is no need to expand the term to cover Haplorrhini as there is no paraphyly required to make the name fit.
Thanks. That makes sense, I think. So, it’s really all down to use of the overloaded term ‘monkey’ in two different clades?
Exactly. In the old system that wasn’t a problem, but with the modern system it isn’t valid.
Thanks for the ‘toe’ the line fix – I had something in my head about it relating to pilots guiding boats in. Entirely spurious no doubt!
so “Homo viscardi” is both an ape and a monkey…
“all apes are monkeys, but not all monkeys are apes” – I presume that sums it up?
In a nutshell.
Oh and it’s Homo viscardiensis Dyke, 1997 if you want to be precise.
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Very interesting and clearly argued. You’ve changed my view on it totally. Thanks.
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That’s pretty accurate! Been busy with work, so Easter has finally given me a chance to write about something more than skulls 🙂
Also, it seemed to be an issue worth wading into…
I don’t think making monkeys into a clade is useful. We’ve got this kind of thing all the time — where a group of animals evolves enough from another that it forms a new species or order.
I’m going with traditional terminology. Apes are somewhat different from monkeys.
But what do you mean by traditional terminology?
If you mean common usage, then apes can be considered monkeys anyway.
If you mean traditional taxonomy then it means species that are not members of the ape clade (like the Barbary Ape, which is a Macaque) should still be considered to be apes. That’s fine if you want to go with that, but it is incorrect with regards to modern taxonomy.
You may not think that making monkeys into a clade is useful, but that’s hardly a logical argument against doing so – and as for apes being somewhat different from monkeys, that’s not really true when considering a traditional taxonomy, which classifies a species of Macaque as an ape.
Having apes as a clade within the monkeys is actually a more effective way of acknowledging the differences between apes and monkeys.
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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’.”
I’m surprised no one pointed out that whales are fish, just like all mammals.
Yes and no. Whales are derived Osteichthyes and can considered to be in the massive bony fish clade, but ‘fish’ isn’t a well taxonomically defined term – consider the useage of ”jellyfish’, starfish’, ‘shellfish’ and ‘silverfish’. The term fish seems to have been applied to anything that moves in water, plus some things that don’t! This makes it so nebulous as to be unhelpful unless you aren’t interested in taxonomy at all.
See the fish comment bothers me, as does reptiles. I agree that the differences are small enough that it’s useful to use Monkey’s to mean Simiformes, but your logic means Either Fish would mean Osteichthyes or Eumetazoa (if we include starfish). And it means Reptiles would include all birds, and I don’t know how useful that is. I mean, birds are more closely related to Crocodiles than Crocodiles are to any other reptile…
Ah linguistics is an illogical mess
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