PEOPLE say, what’s in a name? Well, quite a lot when it is a synonym for a deadly sin.

Yes, the poor old sloth was damned from the moment he was christened after one of the world’s most wicked transgressions. A pretty damaging public relations blow by anyone’s standard.

But which came first: the animal or the sin?

When early European explorers descended upon the Americas in the sixteenth century they encountered many strange animals and described these novel beasts upon their return to Europe.

One of the most notable was Oviedo Valdes, a Spanish knight who published a pioneering Natural History of the New World. A man not known for mincing his words (or telling the truth for that matter) he described the sloth as the stupidest animal on the planet.

Pretty savage words but at least at this stage the sloth had a more upbeat, if somewhat sarcastic name. According to Oviedo some of his fellow Christians were referring to it ironically as ‘Perico Ligero’ or ‘Nimble Peter’. Proof, if proof were needed, why there are so few successful Christians on the comedy circuit.

At this time the Church was already peddling the idea of Seven Deadly Sins – a set of spiritually fatal vices designed to keep the community in check. But sloth – spiritual and physical laziness – had yet to hit the charts.

It wasn’t until the seventeenth century, after years of arguing, the Holy powers-that-be finally decided on its definitive top seven sins. And sloth snuggled in at number four.

Sloth’s new found fame as a bona fide sin provided the largely Catholic explorers with inspiration for a hilarious new nickname for our favourite dozy folivore.

But it was thanks to celebrated French naturalist Georges Buffon that the moniker really stuck, when he became the first person to scientifically describe the sloth in 1749:

‘Slowness, habitual pain, and stupidity are the results of this strange and bungled conformation. These sloths are the lowest form of existence. One more defect would have made their lives impossible.’

It’s lucky the sloth is such an affable chap. And doesn’t read or speak French because, if he did, I’m sure that even he would struggle to swallow such slurs without a (very slow) fight.

Buffon, or Buffoon as I believe it is pronounced, had clearly missed the point. Thanks to Darwin we now understand that natural selection weeds out the weak. Any animal alive today is an evolutionary winner by virtue of its very existence.

But Buffon was well respected and his lengthy diatribe proved an enduring legacy for the sloth’s reputation. Almost a century later Baron Cuvier’s seminal animal encyclopaedia tarred the sloth with a similar brush:

‘Nature seems to have amused herself by producing something so imperfect and grotesque.’

The die had been cast. The sloth’s destiny to be nature’s most misunderstood mammal was set.

But we humans couldn’t have been more wrong. Rather than being a laughable loser the sloth is in fact a miracle of evolution, perfectly adapted to his slow arboreal lifestyle and as we shall discover, quietly rather successful.

What is a sloth?

Sloths are one of the planet’s most enigmatic and eccentric creatures. Famous for being the world’s laziest mammal, these masters of mellow spend up to seventy percent of their time, ahem ‘resting’ and move at an absurdly slow pace, as if they are in, or perhaps on, glue.

Theirs is an inverted existence, hanging about in the trees of Central and South America. They do everything upside-down: sleep, eat, mate and even give birth. Even their fur grows in the opposite direction to normal – with a parting down the middle of their tummy.

These vegetarian pacifists are the original tree-huggers and fall into two distinct families. They look quite different and are defined, somewhat misleadingly, by how many digits they have.

So-called two-toed, Choloepus sloths actually have three toes, but only two fingers and look like a cross between a Wookiee and a pig. They are about the size of a small spaniel, turned upside down with coat hangers for hands.

Their long, thick fur ranges from blonde to brunette but both are equally bad tempered. Solitary in nature, they object to being petted and if approached by something unfamiliar like a hand they will hiss with open mouths to expose a pair of quite terrifying looking teeth. Along with their hooked hands, their dirty great fangs could inflict a nasty wound if their slow-mo swipes weren’t quite as easy to dodge.

Three–toed Bradypus sloths, have three fingers and three toes, medieval haircuts and Mona Lisa smiles. They are slightly smaller than their two fingered cousin – about the size of a domestic cat under all that shaggy mottled grey and brown fur – less cranky but significantly more cryptic. They are far fussier eaters and for this reason rarely survive in captivity.

There are four species of Bradypus including the marvellous maned sloth of Brazil that looks uncannily like a coconut with a mullet. This sartorial sloth, found only in the Atlantic rainforest of Brazil, is most definitely coiffed for business at the front, party at the back.

Perhaps the most peculiar are the pint-sized pygmy sloths; just half the size of regular sloths and only found on a single island off the Caribbean coast of Panama.

These dwarf sloths live in the mangrove swamps and spend their time snoozing and grazing on algae that scientists have discovered contains alkaloids with a similar property to Valium. So they don’t just look stoned. They are stoned. Making them something of an evolutionary cul de sac if ever there was one.

Bradypus and Choloepus sloths are actually only distantly related like cats and dogs, having diverged some 40 million years ago to become genetically quite distinct creatures.

Bradypus for example have small tails and extra neck vertebrae that enable them to turn their heads through 270 degrees and become excellent, if somewhat unlikely, swimmers.

Choloepus have no tail and no extra neck vertebrae, sink like a stone in water and are as such very unlikely to volunteer for a bath.

But despite their obvious differences they both share the same topsy-turvy mellow lifestyle and are lumped together in the same sinful group.

People often mistake sloths for monkeys or bears but they are actually Xenarthrans – an ancient group of mammals that sound like they should be starring in an episode of Star Trek and they have the sci-fi looks to match.

This wonderfully eclectic group includes some of the planet’s most other-worldly-looking oddballs: the armadillos, anteaters and, of course, the sloths.

The sloth’s closest living cousins are the more appropriately named anteaters – an animal that makes its living, erm, eating ants. Lots and lots of them.

The biggest of the bunch, the Giant Anteater, can consume up to 35,000 a day. He achieves this feat using a two-foot tongue that is stickier than a cinema carpet, which he flicks at a rate of 160 times a minute into swarming nests of angry ants. Giving him not just one of the longest but also the hardest-working tongues in the Animal Kingdom.

This fact may or may not be connected with the early European explorer’s fanciful belief that these lumbering beasts were in fact lesbians.

They believed Giant Anteaters were exclusively female and procreated using their fabulous elongated proboscis. These Sapphic nozzle nuzzlers were understandably quite the attraction back in the UK at travelling fairs of New World curiosities.

Hardly a dignified existence for a macho Latino mammal. But then man has not been kind to the Xenarthrans, just ask the Armadillo.

The Aztecs called them ‘turtle rabbits’ which is a fair enough description. With scaly bony plates covering their back, head, legs and tail they resemble a battle-ready rabbit on the Bayeux tapestry. This armour plated carapace enables them to roll into a ball protecting their soft underbelly, much like a woodlouse, when under attack.

Sadly this isn’t enough to protect it from roads. Or people. Armadillos are common road kill thanks to their unfortunate habit of jumping 3 feet in the air when startled; the perfect height to collide with the radiator of a truck.

If the cars don’t get them then the cowboys will. Local Argentinean gauchos consider them the ultimate campfire ready meal, roasting them in their shell for dinner. Then polishing the remains, adding a few strings and using them as a form of ukulele for after supper sing-a-longs.

There are around twenty surviving species of armadillo including the Pink Fairy and the Screaming Hairy. Names, which I’m assured, have nothing to do with their sexuality and everything to do with their eccentric looks.

On the surface this kooky band of modern day misfits appear to have little in common. But closer inspection reveals they all share tiny brains, a distinct lack of front teeth and no external testicles. None of which they are especially keen to publicise. So it’s a good thing they were finally named Xenarthra or ‘strange joints‘ after their other unifying feature – an unusually flexible spine.

The Xenarthra owe their oddness to the fact they evolved in isolation from a common relative when South America was still an island, just after it had torn itself off Africa some 80 million years ago.

Over the millennia, the early sloths diversified into a highly successful group of ground-dwelling mega-mammals, some weighing almost 4 tonnes. Which explains why none of them lived in trees – the branches would have buckled under such great weight.

Instead there were giant aquatic sloths that lounged around on beaches much like a very different form of modern sloth – the British tourist; giant burrowing sloths that excavated underground tunnels two metres wide; and the most successful of the bunch – the giant ground sloths – the largest of which Megatherium looked like an oversized hamster the size of an elephant.

These jumbo vegetarians flourished in a forested land with no natural predators into over one hundred different species, filling all sorts of unlikely niches.

But around 10,000 years ago they disappeared leaving only a handful of diminutive arboreal cousins behind today. What could possibly have wiped out these peaceful giants has long puzzled palaeontologists, who have poured over caves of coprolites – fossilised sloth dung – for clues.

Many believed the last Ice Age finished them off. But no. The awkward answer is we ate them. Yes when South America finally collided with North America about 4 million years ago and the land bridge was formed, some ground sloths ambled north to colonise the great new land. Reverse osmosis saw rather a lot of humans surge south, carrying spears and smacking their lips at the size of these lumbering lumps of meat.

Having survived for many millennia with no natural predators, these brobdingnagian pacifists were an all too easy target and ended up on the barbecue.

It makes sense that the only sloths to survive, did so by shrinking in size and legging it up to the tops of the trees. As quickly as evolution could carry them. Which explains why two fingered and three fingered sloths are as genetically estranged as cats and dogs, yet have such a surprisingly similar arboreal lifestyles. Having been chased up into the trees by hungry humans they are one of nature’s best examples of convergent evolution.

For those, like me, that mourn the loss of these massive majestic beasts there is a chink of hope. Amazon tribal folklore tells of a monstrous creature known as Mapinguari that’s seven feet tall, with thick matted fur and a fetid odour that stalks the deepest corners of the jungle.

Could this legend betray a lost clique of ground sloths roaming the remotest corners of the Amazon? I like to think so.

YOU CAN READ THE FULL LENGTH VERSION OF THIS ESSAY IN THE OCTOBER 2014 HARDBACK EDITION OF THE IDLER’S ANNUAL PERIODICAL

Lucy Cooke is a zoologist and best-selling author of The Power of Sloth. She is founder of the Sloth Appreciation Society, motto “the slow shall inherit the earth”, which slumbers online at www.slothville.com. Lucy is often to be found giving lectures at Idler events. Her show Talk to the Animals was broadcast by BBC1 in July of this year.