Super-strong simians, menacing monkeys, apes with attitude and lethal lemurs – here’s our pick of the primates that kill…
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Deadliest primates on the planet
Mandrill
This elusive inhabitant of equatorial African rainforests is the biggest of all monkeys and arguably the most beautiful. The 30kg males - three times the weight of females - are adorned with a golden mane and striking blue and red swellings on the face and hind-quarters.
Mandrills are also equipped with canine teeth that are amongst the longest of any primate. These are wielded in fights with rivals over dominance. And yet despite the damage they are capable of inflicting - or perhaps because of it - they are used in anger only rarely.
Most disputes are settled without the need for violence. A male’s colouration is a reliable signal of his fighting ability - the brighter the colours, the stronger the male. This allows weaker males to bow out gracefully before push comes to shove. Blood is spilled only when two competing males are closely matched colour-wise.
Slow loris
Don’t be fooled by the round, furry face and puppy-dog eyes, slow lorises are deadly, and in a way that is unique amongst primates - they are venomous.
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These Southeast Asian, nocturnal omnivores - relatives of the lemurs of Madagascar - exude toxic secretions from glands above their elbows. When threatened, they raise their arms and lick the glands to mix the venom with their saliva so it’s ready to be delivered with a bite.
According to humans who have been on the receiving end of slow loris venom, it is extremely painful. Symptoms include oedema, tissue necrosis and anaphylactic shock. There don’t seem to be any records of human fatalities, although there have been a few close shaves.
Some researchers have suggested that the slow loris’s facial markings and defensive posture look uncannily similar to the threat-display of Asian cobras, which are even more venomous. However, the idea that the lorises mimic the snakes as protection against predators hasn’t yet been tested experimentally.
Gorilla
If deadliness were about raw strength alone, the largest of all living primates might top this list. The biggest silverback males can exceed 200kg in weight and are built like brick outhouses. Even leopards steer clear of full-grown adults.
If deadliness were about raw strength alone, the largest of all living primates might top this list. The biggest silverback males can exceed 200kg in weight and are built like brick outhouses. Even leopards steer clear of full-grown adults.
With so much power at their disposal, rarely do they need to resort to physical violence - the threat of it usually suffices. Disputes between rival males are usually settled with dramatic displays of chest beating and false charges. And we couldn’t find a single documented case of a wild gorilla killing a human, even in an age when so many people visit the forests of central Africa to see gorillas in their natural habitat.
Indeed, it’s worth remembering that in 1984, a captive silverback male named Jambo famously stood guard over an injured ten-year-old boy who had fallen into his enclosure at Jersey Zoo and stroked the child’s back until he regained consciousness.
Just don’t push your luck.
Tarsier
Looking like a cross between a teddy bear and Gollum, tarsiers manage to be cute and creepy at the same time.
All fourteen or so species of these tiny, wide-eyed primates are found only on the islands of Southeast Asia. The smallest, the pygmy tarsier of Sulawesi, weighs just 50g - about the same as a chicken egg. The biggest, the Philippine tarsier, is only three times as heavy.
They make this list because they are the only primates that eat meat and nothing but meat.
Hunting at night, guided by their excellent eyesight (each eye is about the same size as a tarsier’s brain), they leap silently from branch to branch in search of insects, arachnids and even small vertebrates.
Just be glad they’re not the size of a leopard, or we’d all be in trouble.
Aye-aye
Also scoring highly on the creepiness scale (although perhaps less so on cuteness) is this unkempt, buck-toothed, big-eared lemur from Madagascar, which fills an ecological niche occupied in other parts of the world by woodpeckers.
The aye-aye’s weapon of choice is its middle finger, an extraordinarily long, bony, and highly manoeuvrable implement that it uses to extract insect grubs from deep within tree trunks and branches.
First, it taps the wood with its finger and listens to the echo to locate hollow cavities within. It then uses its rodent-like front teeth to gnaw an entry hole before inserting a probing finger to hook out its prey.
The finger has other uses, too, doubling up as a highly effective nose-picking tool. Aye-ayes have been documented sticking a finger - all 10cm of it - into their nasal cavity and feasting on the snot they pull out.
Gigantopithecus
The deadliest primate that ever lived may also have been the biggest. Known only from fossil teeth and jaws found in southern China and Southeast Asia, Gigantopithecus was an ape of truly gargantuan proportions.
This relative of the orangutans would have stood around three metres tall and weighed as much as 300kg. On the evidence of its enormous molars, it ate tough, fibrous plant material.
We might never know the true strength of Gigantopithecus, because the species vanished around 250,000 years ago — long before humans reached that part of the world. Otherwise, someone could have challenged it to an arm wrestle to settle the matter once and for all.
Capuchin
These clever little monkeys are most famous for being the only South American primates that have a culture of tool use, using stones as tools to crack open tough nuts. They are less well known for their role in the natural cycle of one of the deadliest diseases in human history.
Yellow fever is caused by a virus that circulates between tropical mosquitoes and several species of monkey. Some of these monkeys - capuchins included - can survive infection while carrying enough virus in their blood to infect biting mosquitoes.
Humans become involved only when infected mosquitoes bite people living or working nearby. Once the virus reaches towns and cities, it can spread rapidly between humans via urban mosquitoes.
Before vaccination programmes and mosquito control measures curbed the disease, epidemics repeatedly swept through tropical settlements. Thousands of workers were killed by the virus during the early attempts to build the Panama Canal.
Capuchins themselves are harmless enough. The virus that travels with them through the forest is anything but.
Chacma baboon
A chacma baboon is intimidating animal when it’s on its own, let alone when it’s part of a mob.
Found across southern Africa, this large, powerful monkey lives in troops that can number more than a hundred individuals. Adult males weigh over 30kg and brandish formidable canine teeth. These vicious weapons are wielded against rivals and predators, such as cheetahs…
and leopards…
Chacmas are also bold opportunists around humans. In parts of South Africa they raid houses, cars and backpacks, and aggressive encounters with people are well documented, although serious injuries are uncommon.
Chimpanzee
It’s too easy to see ourselves in the behaviour of our closest relatives. Which may be why it’s so hard to watch footage of troops of chimpanzees chasing down and tearing apart the writhing bodies of monkeys in the treetops.
These are expeditions that involve intelligence, cooperation and utterly brutal violence. Individuals perform different roles within the hunting party. Some drive the prey through the canopy, while others block off escape routes or anticipate the prey’s movements and ambush them.
These hunts are not rare events. They have been documented in Tanzania, Côte d’Ivoire, Uganda and Gabon. InTanzania’s Gombe National Park, researchers observed chimps killing 35–40 red colobus monkeys per year. The Ngogo chimps of Kibale National Park, Uganda, take enough colobus to limit their population size.
All of which suggests that chimpanzees are a rare example of a primate that sits at the top of a food chain - an apex predator - a role usually associated with classic carnivores such as wolves, bears, big cats, sharks and raptors.
Human
But chimps are not the only apex predators among the primates. What Homo sapiens lacks in terms of fangs, claws and venom, it more than makes up for with brains capable of imagining and building weapons that can kill on a scale unmatched throughout evolutionary history.
It started with sharpened sticks and stone-tipped spears and progressed through knives, gunpowder, bows and arrows to kalashnikovs, guided missiles and thermonuclear devices.
Meanwhile, we have developed ever more ingenious ways to extract food, land and materials from the natural world at the expense of species, habitats and, increasingly, our own sense of regret.
Being the sharpest tools in the box comes at a cost.
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