Apparently I have a thing for misunderstood creatures.
Whereas in popular culture “weasel” has become synonymous with dishonesty and is seen as almost without virtue, I actually like them. The combination of lithe grace and almost unparalleled fierceness appeals to me.
Similarly, the sloths are some of my favourite animals of all God’s creatures, despite their reputation.
Sloths have a bad press. Not as completely evil as the weasel, but a byword for lazy, viewed even by some naturalists as primitive, ungainly, ugly and stupid. The Ice Age trilogy had as its most completely annoying character Sid the Sloth. Admittedly, Sid is supposed to be a ground sloth, but that actually makes it worse. Ground sloths are even cooler than their modern descendents.
What virtue can I possibly find in this creature that moves at just over one mile an hour when going flat out and doesn’t even have enamel on its teeth?
There are three species of sloth remaining in the world: the two-toed sloths of the genus Chololepus and the three-toed sloths of the genus Bradypus.
This is all that remains of one of the most successful animal groups ever to come out of South America. A group which included Megatherium, a ground sloth that weighed about the same as an African elephant, stood on its back legs as tall as a giraffe and had strong enough arms to roll over a VW Beetle. A group that included Thalassocnus, an animal that pushed the limits of bizarrity even for sloths, being a marine animal adapted to swim out to sea and graze on seaweed.
A lot of sloths’ poor reputation stems from the attitudes of the early European naturalists who first described them. Here was an animal that was so different to anything that was already known from Europe, Africa or Asia that it was difficult to know what to make of it. It looked lumpy, hung upside down all the time and moved at a ridiculously slow rate. Its teeth lacked enamel. It actually had algae that grew on its fur. Its metabolic rate was so slow that it rivalled that of a sleeping bear. It wasn’t even all that good to eat.
And European naturalists being European naturalists and in love with the pseudo-Darwinian idea that there were “superior” and “inferior” creatures (and “superior” and “inferior” races of people), they dismissed the sloth as “primitive”. After all, wasn’t it self-evident that the European races were inherently superior, and those of Northern Europe most superior of all? In like manner, the creatures of Europe and its environs were automatically assumed to be superior to anything else, and the more unlike anything European something was, the further down the evolutionary totem pole it belonged.
Personally, I question the assumptions that led to this.
Sloths are perfectly designed for their environment and lifestyle. Everything we tend to think is primitive or just plain dumb is actually another adaptation to its way of life. It’s just adapted very differently to anything European.
Sloths are browsers; they feed on leaves. This is the central defining truth of the sloth, and explains almost every aspect of their oddity.
Leaves, you see, are a particularly low-calorie food. Anyone on a diet will be able to vouch for the fact that 8oz’ worth of lettuce leaves contains dramatically fewer calories than an 8oz steak. And since calories are a measure of energy, what this amounts to is that leaf-eaters don’t get as much energy per ounce of food. Leaves are difficult for animals to break down, and most animals that graze or browse have huge guts that are effectively chains of vats full of the microorganisms that can break the stuff down.
Old-World, European-type grazers and browsers are adapted to the low-energy nature of their food by spending almost all of their waking hours engaged in eating. A field of cows do practically little else; deer are the same, except with tree leaves rather than grass. They maintain a high-energy lifestyle – running and jumping and so on – by continually replenishing that energy by eating.
Sloths have a completely dfferent approach to the realities of their diet. Rather than try to maintain a high-energy, highly-active lifestyle, the sloths slow down so as not to expend any more energy than they absolutely have to.
Their metabolism is slower than any other vertebrate on the planet. Their body temperature is several degrees cooler than most mammals’, because running the furnace of an ectothermic (“warm-blooded”) metabolism at the rate of most mammals takes an awful lot of energy. By comparison, sloths are practically cold-blooded.
They hang upside-down because with their hook-shaped claws, it takes far less energy and muscle than supporting oneself on one’s limbs.
They move at the fantastic speed of 1.2 mph at what for a sloth is a flat sprint because they don’t have much muscle. Muscle takes energy to make and maintain, and energy to operate, and sloths have one simple rule: minimise energy expenditure.
Their unenamelled dentine teeth are another adaptation for their leaf-eating lifestyle. Mammals only get a maximum of two sets of teeth in their lives. This is a consequence of the way mammalian teeth have different designs depending on where in the mouth they are, and the way they interlock with each other. Mammals have some of the most complex teeth of any creature. In addition, like most other vertebrates, the teeth of all other mammals are covered in enamel. Tooth enamel is the hardest substance produced by the body; far harder than bone. It forms a thin layer over the outer surface of the tooth; under this is the dentine; a substance very similar to the bone in the rest of the skeleton.
Forming all of these complicated teeth, shedding them and growing a new set takes, you’ve guessed it, energy. Energy a sloth doesn’t have. Enamel is difficult to grow, mostly because of its hardness, and leaves are particularly tough on vertebrate teeth. It’s this more than anything else that contributes to mammals’ two tooth set limit.
Most animals than eat plants don’t have fully-enamelled grinding teeth. An elephant’s teeth, for instance, are a complex set of enamel ridges with dentine in between. Beavers and other rodents have incisors that keep growing all their lives, but those teeth are only enamelled on the front side.
Sloths have taken the process a step further. Their teeth don’t have any enamel at all. In addition, they are designed so that their continually-growing dentine teeth self-sharpen as they bite and chew their food. If you look at it from the sloth’s point of view, the feature that more than any other gets dismissed as a “primitive” trait is actually one of their most advanced adaptations.
Perhaps surprisingly, sloths can swim, and do so pretty well. There are whole sections of the Amazon basin that have such intense seasonal floods that whole areas of forest get submerged, becoming the eerie “drowned forest”. In this season, sloths actually belie their name and exhibit a pretty respectable turn of speed through the water. At least, for an animal famous for being slow. The sloth in the water isn’t going to be winning any races against penguins or seals, but he can move much faster in water than hecan on land.
The sloths’ extinct cousins the ground sloths were even more amazing. Including over 27 species in 19 genera, they were one of the few types of animal to successfully colonise North America from South America. When the last ice age ended and they became extinct, they were poised to cross the Bering land bridge into Asia. Their low metabolic rate gave them an advantage over other similarly-sized creatures, because they needed less food. They were large and strong, and it’s thought that some of the larger varieties might have supplemented their plant diet with occasional scavenging of carcasses, or even hunting. Certain Glyptodon (extinct giant armadillo weighing about the same as a VW Beetle) skeletons have been found inexplicably belly-up, and the giant ground sloth is the only thing we know about with the strength and leverage to roll one.
So sloths are awesome.
But what lessons might we get from our new knowledge of the true nature of sloths?
They’ve been dismissed for years as an object lesson on not being lazy. Their very common name is taken from the Seven Deadly Sins’ version of laziness. But if we’ve established that most of what we thought we knew about sloths is either wrong or prejudiced, what moral lesson might we draw instead?
The most obvious and timely one is simply to slow down.
The frenetic pace of life is one of the things that draws more contemporary ire than anything else. People work flat-out all the time, particularly here in the States where hard work is considered perhaps the chief of virtues. Even when we take a day off, we’re rushing off to the beach or spending the day mowing the lawn and repairing the car and the house. Our free time is something many of us claim to treasure, even while we don’t actually engage in it when we have the opportunity. I know a man who has “retired” three or four times and then come back to work, not because of financial necessity but because he just couldn’t keep away.
We are a generation of instant communications, fast internet and high-speed data sharing. We want results instantly and get impatient or frustrated when we can’t get them. As evidence, look at your driving habits. If you’re anything like me, about the worst possible situation on the road is to run into a delay caused by an accident, a traffic light misbehaving, or simply some idiot being an idiot on the piece of road you want to use.
I have to remind myself that really, it’s ok. I’m a follower of Jesus, so I’m actually going to live forever. What’s the rush?
Patience is probably the least practiced and most sought-after virtue in the modern world. The ability to set aside worry and activity and just wait.
It’s an area where, metaphorically, the sloth excels. In fact, if we were to have named the sloth after its virtues rather than its vices, it would undoubtedly be called a Patience.
We might also learn other lessons, though. Wisdom, for example. As with the sloth’s self-sharpening teeth, it’s a wise and learned individual who can in all humility sharpen themselves. We are told in the Proverbs about one man sharpening another, but to self-sharpen? It takes both the wisdom and learning to be able to use what one has to get sharper, and the humility to know exactly when you are self-sharpening and when you are fooling yourself.
Or perhaps just an appreciation for the despised. If a sloth were judged by its ability to run, it would be believed worthless. Sometimes we believe this of ourselves, or of other people. Maybe we’re just like the sloth: so uniquely different that people have a hard time understanding us.
Maybe the ability to swim in the flood of God’s presence. In the water, the sloth doesn’t need to use its weak muscles to support itself, only to gain forward motion. Or as the Scripture puts it: “He chose the weak things of this world to shame the strong”.
This peculiar wisdom of the slow comes naturally to the sloth, but is anything but natural to us in our busy, fast-paced lives.
Perhaps we could do with rehabilitating the sloth’s reputation and learning from the master of slow wisdom.