We share roughly 99% of our DNA with chimpanzees, 98% with gorillas, and 97% with orangutans, says Will Newton. It’s no wonder, given such stark genetic similarity, that these great apes are often referred to as our closest living cousins.
Are humans apes?
Together, we (Homo sapiens) and the seven other extant species of great apes (chimpanzees, bonobos, eastern and western gorillas, and Bornean, Sumatran, and Tapanuli orangutans) make up a group known as Hominidae.
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This group is part of a larger group known as Hominoidea, or apes. As well as great apes, Hominoidea also includes gibbons - the only apes that don’t quite make the cut as great apes.
As part of Hominidae (and therefore Hominoidea), humans are both great apes and apes. The terms ‘great apes’ and ‘apes’ are just common names for wide-reaching taxonomic groups that include both living and extinct animals. A simple way to look at this is that humans are apes, but not all apes are humans.
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So, if humans are apes, why do we look and behave so differently to chimpanzees, gorillas, orangutans, and gibbons? The best way to explain these aesthetic and behavioural differences is by looking at our shared ancestry and identifying when each group broke away from the wider ape family tree.
When did apes first appear?
From a combination of genetic analyses and fossil evidence, researchers have worked out that hominoids (apes) diverged from Old World monkeys in the Oligocene, roughly 25 million years ago. In the following period, the Miocene (23-5.3 mya), apes reached a peak in diversity and evolved into lots of different groups - many of which are now extinct.
This peak in diversity is thought to have been driven by a more favourable climate and increased habitat diversity in the Miocene compared to the Oligocene. As temperatures increased in the Miocene, vegetation blossomed and huge, expansive forests spread across the world, creating many different ecological niches that apes could evolve into.
During the Early Miocene, Africa and the adjoining Arabian Peninsula also collided with Eurasia, creating a land bridge that allowed apes to migrate across continents and spread to new and even more ecologically favourable areas.
What was the first group of apes to diverge from the rest?
The first group to break away from the ape family tree were the gibbons (Hylobatidae), and they did so roughly 16.8 million years ago.
Also known as ‘lesser apes’, gibbons differ from the great apes in being a lot smaller, exhibiting low sexual dimorphism (differences between males and females), and having strangely long arms in comparison to the rest of their bodies. They’re also distinguished from great apes by the fact they don’t make nests.
There are 20 different species of gibbons alive today and they can be found in subtropical and tropical forests from eastern Bangladesh and Northeast India to Southeast Asia and Indonesia.
What groups of apes diverged after gibbons?
Just a few million years after gibbons diverged and established the only group of lesser apes, the first of the great apes appeared - the orangutans (Ponginae).
Orangutans are the most arboreal of the great apes and spend more time lazing in trees than any others. They’re also the most solitary. However, that doesn’t make them any less intelligent - in fact, orangutans are widely considered the second-most intelligent primate after humans. They’ve been documented using a variety of different tools, constructing elaborate nests from branches and leaves, and even learning sign language.
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Pongo is the only surviving genus of orangutan and includes three extant species: the Bornean orangutan, the Sumatran orangutan, and the Tapanuli orangutan. All three of these species are critically endangered and native to the rainforests of Indonesia and Malaysia.
While large - weighing in at around 37kg (females) and around 75kg (males) - living orangutans are dwarfs in comparison to the extinct genus Gigantopithecus. This 300kg, gorilla-like orangutan lived in southern China during the Pleistocene and only faced extinction as recently as 200,000 years ago.
After orangutans, gorillas emerged roughly 8 million years ago. They are the largest living primates and are known to reach heights of close to 2m and exceed weights of 270kg.
Like us, gorillas live in large familial groups known as troops. However, unlike us they’re primarily herbivorous and, like gibbons and orangutans, survive on a diet of mainly leaves, stems, bark, fruits, and seeds.
There are two species of gorillas, the eastern gorilla and the western gorilla, and both live in Sub-Saharan Africa, ranging from cloud forests in Rwanda to lowland swamps in Angola.
After bonobos and chimpanzees, gorillas are our next closest living relatives - our second cousins once removed, if you will.
The last group to branch off from the ape family tree before humans appeared were the panins - not a type of grilled sandwich but a subgroup of great apes that includes chimpanzees and bonobos. They did so roughly 6.5 million years ago, towards the end of the Miocene and at a time when diversity amongst apes was beginning to ebb.
Chimpanzees and bonobos are native to the forests and savannahs of tropical Africa and are known for their ever changing and often fiery social structures. They live in groups of 15 to 150 individuals, led by an alpha male who tops a dominance hierarchy of other males.
The similarities between chimpanzees and bonobos run deep, but there is a significant size discrepancy. Historically, bonobos were known as pygmy chimpanzees and, on average, weigh in at around 40kg. Chimpanzees, on the other hand, tip the scales at roughly 50kg, though some individuals are known to exceed 100kg!
While they have a particular taste for fruit, chimpanzees and bonobos are omnivorous and will eat pretty much anything they can find, or catch. This includes everything from tree resin to small monkeys, such as the red colobus. Chimpanzees have also been observed creating spears from sticks and using these to hunt bush babies.
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Like orangutans, chimpanzees and bonobos have passed the famous mirror test, suggesting a degree of self awareness and high levels of intelligence. Some gorillas have also passed the mirror test, though results are inconsistent and nowhere near as positive as those seen in other great apes.
When did humans first appear?
There are many animals that fall in between us (Homo sapiens) and panins (chimpanzees and bonobos) on the ape family tree, and many of these animals could be described as ‘human’, or at least human-like.
They include the diminutive, chimp-like hominid Ardipithecus ramidus, the stocky, herbivorous hominid Paranthropus robustus, and the hairy, tool-wielding ‘handy man’, Homo habilis.
There’s a lot of debate surrounding the origin of humans and what animals fit the description of ‘human’, but the consensus is that the ‘human’ branch of the ape family tree began 2.3 million years ago (but possibly earlier) with Homo habilis.
This 1.3m-tall (4ft 3in) human looked somewhat like a cross between a chimp and a modern human; it was covered head to toe in hair and it had proportionally long arms designed for climbing trees, but it had a flat face and it could walk upright. It could also use and manufacture stone tools - a hallmark of species within the Homo genus.
After Homo habilis came a series of increasingly more human-like humans, such as Homo erectus (2 million years ago), Homo heidelbergensis (700,000 years ago), Homo neanderthalensis (400,000 years ago) and - finally - Homo sapiens.
As a species, Homo sapiens emerged 300,000 years ago. That may sound like a long time ago, but in terms of geological time it equates to roughly a handful of seconds if the entirety of Earth’s 4.5-billion-year history was condensed down into a single, 24-hour day.
What's the difference between humans and other apes?
This may come from a place of bias, but as apes go humans are pretty special. For starters, our brains (around 1,300cm3) are larger than those of any other apes, living or extinct*.
*There’s evidence to suggest that Neanderthals had larger brains than modern humans, but researchers don’t think this necessarily translated to increased intelligence.
Another trait that differentiates us from other apes is our ability to walk upright for long periods of time. This is known as bipedalism and it’s a trait that may have evolved long before humans became ‘humans’ - some researchers have suggested the last common ancestor between chimps and humans, the infamous ‘missing link’, likely walked on two legs.
We’re also a lot less hairy than other apes. This is a trait that likely evolved in early members of the Homo genus, during a time when humans were leaving the safety of the trees behind and adapting to life on the plains. To survive on the plains, our ancestors had to run long distances - by losing their hair and increasing the number of sweat glands across their body, they were able to stay cool.
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We’re gossips too, blessed with the ‘gift of the gab’. Other apes communicate with one another using a combination of hoots, facial expressions, and arm waving, but none can produce the sheer range in sounds that humans can. It’s this range that allows humans to converse in over 7,000 different languages.
It’s easy to forget, given these differences, that humans are actually apes. However, all it takes is one look at a chimpanzee nursing a newborn, a silverback gorilla chasing his teenage son, or an orangutan donning and zipping up a jacket, to remember that we’re actually not so different from our closest cousins.
At the end of the day, we’re all apes and we’re all driven by the same, natural instincts: to care, to love, to protect, and to eat bananas…