The zoologist Jordi Casamitjana gives the ultimate vegan answer to the “canines, though” remark vegan sceptics often throw at vegans when they attempt to argue that veganism is unnatural
I find it quite bizarre.
I know that when a vegan sceptic wants to annoy vegans like me, they will try to throw us all sorts of ridiculous arguments and remarks hoping to paralyse us with a logical blow that would demolish our vegan philosophy to smithereens. Things like, “Plants feel pain too”, “If we are not meant to eat animals why do they taste so good?”, or “If people stopped eating animals, they would become extinct”. Some are easily ignored as they are kind of tongue-in-cheek cliches just said trying to annoy us (such as “bacon, though”). Some are more subtle and passive-aggressive, such as the question “Where do you get your protein from?”, which I have already dealt with in another article. We are used to all of these, and we can easily neutralise them and deflate the puffiness of the vegan sceptic who was hoping for a quick argumentative victory.
However, there is one remark that has often baffled me, because it is one of the weakest trolling throwbacks, and yet it is often delivered with a huge amount of confidence and smugness. One that often comes accompanied by the gesture of pointing to one’s teeth, for an extra visual punch. One that has become a classic among veganphobic trolls. I am talking about the snarky remark, “Canines, though.”
This minimalistic remark could be expanded to, “How do you explain that we have canine teeth if we are not meant to eat meat?” What they are trying to say is, “If the vegan diet was natural, humans would not have canine teeth, and as humans do have them, this proves that we must eat meat.” We, vegans, know how to respond to this strange argument because, frankly, the answer is so obvious that it defies logic someone would use it as a kind of “checkmate” argument.
However, as the zoologist I am, and therefore as someone who studied a degree where canines of multiple species feature significantly, I thought I could perhaps devise a very detailed and authoritative zoological answer that would bury this bizarre remark once and for all. One that could be considered the ultimate vegan answer to the naïve “canines, though” remark. Here it comes.
What are Canines?
The word “canine” has two connected but very different meanings: a dog (or quality of dogs when used as an adjective), and a pointed tooth between the incisors and premolars of a mammal. The connection is that the canine teeth are often greatly enlarged in carnivores (animals adapted to eat meat), and dogs belong to the Family Canids, which are part of the Order Carnivora, which in English is often referred to as Carnivores, although they should be referred to as Carnivorans. The term canine derives from the term canid because dogs have especially prominent canine teeth, that’s pretty much it. Here we will only look at the concept of canine as a type of teeth because this is what the remark in question refers to.
A canine tooth, also called cuspid or eye tooth, is any single-cusped (pointed), usually single-rooted teeth originally adapted for tearing food and occurring behind or beside the incisors (the front teeth). Note that one of their main adaptations is to tear food of any kind, not only meat, and their definition relies more on its topography (where they are in relation to other teeth, in this case besides the front teeth) than on its shape.
One could say that a canine is a very specific type of fang. Fangs are large sharp teeth that can be found in many mammals (where the term tends to be restricted to the very long canines from the upper jaw only), but also reptiles (as the venomous fangs of a snake) or invertebrates (such as the fangs of a spider). However, this description would not be quite accurate, because you can get canines that are not large and sharp, but they are still called canines.
Mammals generally have four canine teeth, two in the upper (maxillary) and two in the lower (mandibular) arch. A canine is placed on the side of each lateral incisor and in the middle line of the premolars, the next type of teeth in the jaw. Canines are normally larger and stronger than the incisors, their roots sink deeply into the bones, and they are the only teeth with a single cusp.
Canines in Mammals
The number of teeth present in each tooth class varies among mammals and is not only important as a taxonomic consideration but also as a functional adaptation. The function of incisors is food intake and grooming, whereas canines pierce or stab food, and/or contribute to aggressive displays. The premolars and molars mechanically process the food before swallowing it by tearing it and crushing it.
Evolution has changed the number and shape of the teeth in mammals. Many mammals still have canines, but the shape may vary depending on which part of the jaw they are, and what they are used for (not always for eating). Carnivores such as lions or wolves have long canines, which they use to hunt. Sheeps, cows, and deers (all herbivore mammals), also have canines, but only the upper canines are large, while the lower ones resemble incisors. However, the Chinese Water Deer (Hydropotes inermis) has very long canines that stick outside the closed mouth, and they are still herbivores like any other deer. Rabbits and rodents lack canines altogether, even those who eat other animals (rats eat meat and fish, and the Southern Grasshopper Mouse Onychomys torridus is a predator). The tusks of wild boars and walruses are very enlarged canines, and the biggest canines are found in hippopotamuses (also herbivores). Elephants have no canines, but, interestingly, their tusks are upper incisors. The males of pigs, baboons, and gorillas have much larger canines than the females, as these are used for threatening behaviour.
In many animals the canines are the largest teeth in the mouth, projecting beyond the level of the other teeth and may interlock when the mouth is closed, restricting the animal to an up-and-down chewing action as opposed to sideways. This is not the case for humans, who have small canines that project slightly beyond the level of the other teeth, so humans can have rotary chewing action (as can herbivore mammals).
Mammalian teeth have evolved from an ancestral conical shape, or one-cusped, tooth to progressively more elaborate shapes, so one can say that the first mammals (small shrew-like creatures) had all the teeth pointed — looking more like canines — and later some of the teeth diverged and became more specialised (like incisors to cut or molars to crush). Morganucodon is usually considered the oldest mammal discovered, and its oldest fossils (only represented by isolated teeth), date from around 205 million years ago. Palaeontologists believe that they ate mostly insects and other small animals, with a preference for hard prey such as beetles. Their teeth grew with deciduous teeth being replaced by permanent teeth that were retained throughout the rest of the animal’s life, and they already had canines and molars with different shapes (although they all were still pointed, with molars with two additional points by a bigger one, instead of just one like in canines).
The all-pointed teeth that these primitive insectivore ancestral mammals show are similar to those mammals today of the old Order Insectivora (now divided into the order Eulipotyphla and Laurasiatheria), such as shrews and hedgehogs, also adapted to eat insects and other invertebrates. The big carnivores such as tigers, wolves, and polar bears not only have large canines but have pointed teeth all over their jaws, as premolars and molars are also pointed (not only do they need to “stab” and “pin down” their prey when they hunt — otherwise they would scape — but they also need to be able to tear their flesh apart).
From the ancestral shrew-like mammals, two distinctive groups evolved, the marsupial mammals (today only found in Oceania and America) and the placental mammals (found everywhere — we are one of them). The dentition of primitive living placental mammals includes 3 incisors, 1 canine, 4 premolars and 3 molars in the upper and lower toothrows on each side of the face. For marsupial mammals, the primitive number of teeth in each tooth class was 5 incisors, 1 canine, 3 premolars and 4 molars in the upper toothrow, and a similar number in the lower toothrow, except for only 4 incisors. An evolutionary mammalian trend of increasing the number of cusps per teeth and decreasing the number of teeth is seen through most mammalian groups.
In mammals with large canines, the “canine honing complex” is a functional complex where a long, conical, projecting upper canine is continually sharpened by rubbing against the lower second or third premolar, so even if the animal gets older the canines remain sharp. Not all mammals have this complex, and we, humans, don’t.
Considering the variation of uses of canines in mammals, the mere existence of canines in your mouth should only make you conclude you are a mammal, so the “canines, though” remark in this context is only a valid remark for anyone who says humans are not animals, or humans are not mammals. I suspect that those who use this remark with a debunking intent may well be human supremacists who think humans are not animals, so the remark would be what a vegan would say to them, not the other way around — hence why I find it bizarre.
Also, the fact that insectivore mammals (the current and archaic ones) have most of their teeth pointed like canines tells us that, if we humans only have four pointed teeth left, we are no mammals adapted to an insectivore diet like hedgehogs (which is another type of “carnivorous” diet).
Canines in Primates
Primates are an Order of mammals that include lemurs, lorises, tarsiers and anthropoids (which in turn are comprised of monkeys, apes and humans). Hominoids belong to the superfamily Hominoidae and are distinguished from the rest of the primates by their absence of tails and flexible shoulder joints. The term Hominoids refers to Hominins (current humans and their extinct ancestors of genera Homo, Australopithecus, Paranthropus and Ardipithecus) and apes (gorillas, chimpanzees, orangutans, bonobos, siamangs and gibbons).
All primates have, for each quarter of their mouth, two incisors, one canine and three molars but varying numbers of premolars (no living primate has four premolars, three premolars per quadrant/toothrow are found in lemurs and new world monkeys, and two premolars in old world monkeys, apes and humans). The posterior-most premolars evolved to have either one or two extra cusps as opposed to primitive premolars that are unicuspid, and modern primates have four or five cusped molars instead of the primitive three-cusp molars.
The tooth morphology of primates is adapted to eat plants and mixed food. Incisors bite off pieces of food and the premolars and molars grind them. Frugivore primates (those adapted to eat fruits) have relatively larger incisors to be able to de-husk fruits and seeds and their molars are bunodont (which means they have cusps that are separate and rounded). Folivore primates (leaf-eating), on the other side, have smaller incisors and molars with relatively higher cusps, sharp shearing crests and larger crushing surfaces, so they can chew for longer. Finally, insectivore primates (insect-eating) have smaller molars with sharp cusps to puncture insect exoskeletons. Despite the fact some primates (such as chimps) occasionally hunt vertebrates (but this is rare and only forms a tiny part of their diet, no more than 2%), there are no primate species that are carnivores, other than the insectivore primates (such as the tarsiers).
The canine honing complex mentioned earlier is a nearly ubiquitous functional complex in the teeth of anthropoid primates. During early hominin evolution, the canines and honing premolars were altered in size and shape, which resulted in the loss of functional canine honing. However, that’s not a big deal because primate canines do not need sharpening as much as the canines of carnivore mammals do, as they are used in less abrasive ways.
Instead, in most nonhuman anthropoid primates, canines are used in visual threat displays and occasionally as weapons for biting during fights. Although many anthropoid primates have big projecting canines, their size varies between sexes and among species. The species with high intensity and frequency of fights and threats have larger relative canine sizes than species with less frequent and less intense agonistic behaviour (and this can be seen in both males and females).
The mere existence of four non-honing canines in your mouth as your only pointed teeth should only make you conclude that you a primate, so the “canines, though” remark in this context is only a valid remark for anyone who says humans are not primates. The number does not really tell you if you are a leaf-eating, fruit-eating, or insect-eating primate, but as we saw earlier, the other teeth rule you out as an insectivore primate, which means that the only remaining adaptations that your teeth suggest as of non-carnivorous dietary adaptations (either frugivore or folivore) —again, the opposite to what those using the irritating remark intended.
Therefore, so far, we can say to the vegan sceptics who point to our teeth, “Yes, we are animals with teeth; yes, we are mammals with canines; yes, we are non-carnivorous primates with only four pointed teeth.”
Canines in Humans
The dentition of modern-day humans is more similar to the one of anthropoid apes than any other dentition of any other animal. Anthropoid apes are the gibbon, siamang, orangutan, gorilla, chimpanzee, and bonobo, and none of these apes are carnivorous animals. All of them are either folivores (gorillas) or frugivores (the rest). This is already telling us that we are not a carnivorous species and that the likelihood of humans having a frugivore adaptation is higher than having a folivore/herbivore adaptation.
There are important differences between human teeth and those of the great apes, though. Since we split from the apes about 7 million years ago, evolution has been changing the teeth of the hominid lineage. The extra-large, dagger-like canine teeth seen in male great apes have been missing from human ancestors for at least 4.5 million years. As long canines in primates are more related to status than to feeding habits, this suggests that male human ancestors became less aggressive with each other around the same time, possibly because females preferred less aggressive mates.
Modern-day humans have four canines, one in each quarter jaw, and males have proportionately the smallest canines of all male great apes, but they have oversized roots, which is a remnant of the large canine of the apes. The evolution of hominoids from the Miocene to the Pliocene period (5–2.5 million years ago) saw a gradual reduction in canine length, enamel thickness of molars and cuspal heights. By 3.5 million years ago, our ancestors’ teeth were arranged in rows that were slightly wider apart at the back than at the front, and by 1.8 million years ago, our ancestors’ canines had become short and relatively blunt like ours.
Across all teeth, hominin evolution showed a reduction in both crown and root sizes, with the former probably preceding the latter. A change in diet might have reduced the functional loads on dental crowns causing a subsequent reduction in root morphology and size. However, this does not necessarily point towards hominids becoming more carnivorous (as skin, muscles and bones are tough, so you would expect an increase in root sizes), but could be towards eating softer fruits (such as berries), finding new methods to break nuts (such as with stones), or even cooking food (fire was mastered by humans from about 2 million years ago), which would give availability to new vegetable foods (such as roots and some grains).
When we compare humans to our closest relatives, the chimps, we find that we have more copies of the genes for the enzymes that allow us to digest starches, suggesting that highly starchy roots and grains are what drove our latest evolutionary adaptations, rather than meat. So, although cooking would have made it easier to eat meat, the only genetic and physiological changes we see happening after hominids learned to create fire were related to access to new plant-based food. Besides, as the reduction of canines preceded the time when hominids controlled fire, this shows that any increase in the accessibility of meat because of cooking was not the cause of the reduction of canines’ size.
There were savannah hominids now extinct who were even more adapted to a herbivorous route than their forest ancestors and us, as they showed even more robust molars than we have. The carbon isotope analysis of the teeth of Australopithecus groups in eastern Africa, the first hominids who lived in the open savannah (before hominids mastered fire), shows that they fed mostly on grasses. In South Africa, the data shows that Australopithecus groups ate hard, brittle foods like nuts, roots and seeds, so by leaving the forests and moving to the plains the diets remained plant-based, but moved from a frugivorous diet of soft fruits to a herbivorous diet of harder food. However, when the Australopithecines evolved into Homo, and began using stones and fire, some of them did not need to have bigger molars as they could now process and cook food, and this is the lineage that evolved into us — so, in a way, fire prevented us to transition from frugivores to full grass-eating herbivores, keeping the frugivore adaptation we acquired in the trees.
We know that, in primates, canines have two possible functions, one is to de-husk fruits and seeds and another is for display in intraspecific antagonistic encounters, so when hominids moved out from the trees into the savannah changing both their social and reproductive dynamics as well as part of their diet, if this was really a move towards carnivorism there would have been two opposite evolutionary forces changing canine size, one toward reducing it (less need for antagonistic displays) and another toward increasing it (to use the canines for hunting or tearing up meat), so probably the size of canines would have not changed much. However, we found a substantial reduction in canine size, suggesting that there was no “carnivore” evolutionary force to increase canine size when they changed habitat, and hominids continued being mostly plant-based.
Another piece of evidence suggesting that the reduction of canine size had to do with the loss of aggressive display function is that, today, on average, men have 10% longer canines than women, a sexual dimorphism that we find more pronounced in gorillas, our leaf-eating cousins. In gorilla society, males compete for exclusive mating rights to the entire female troop, and the male with the longest, most intimidating set of fangs often wins. This social structure was no longer present in the first hominids, so the size of the canines was reduced, but as the split from apes did not happen that long ago, we can still see traces of that past.
The reduction of canine size in hominid evolution was so pronounced that today many humans have canines that are shorter than incisors (have a look at the actress Anne Hathaway, for instance) — which, interestingly, is what you would expect if the human diet had become more herbivorous. Besides, with shorter canines that no longer prevent side-to-side movement of the jaws when chewing, humans are better adapted to chewing seeds, nuts, grains and vegetables (carnivores often swallow meat without chewing much), and as we have robust molars and premolars well equipped for chewing, we are anatomically well adapted to eat a plant-based diet
Although we may still use our canines to bite semi-hard fruits such as apples, it appears that the only function that they have today in humans, which explains why they have not become just another set of incisors, is what scientists call “canine guidance”, which is separating the premolar and molar teeth of either jaw during sideways movements and so protecting them from fractures. With the canines from the upper and lower jaw touching each other, they leave a gap between the premolars and molars from both jaws, decreasing the eroding risk. So, in modern humans, canines are no longer status or eating teeth but have become “safety” teeth. That’s why they have not become bigger, sharper, or stronger in humans.
Debunking the “Canines, though” Remark
When we look at the issue of teeth from a zoological and paleontological perspective, it becomes clear that our teeth, including our canines, tell us that we are not a carnivore species, and that eating animals, either small insects and invertebrates or meat from fishes, birds, and mammals, is not the diet we are most adapted to thrive with. They tell us that we are animals, that we are mammals, that we a primates, that we are anthropoids, that we are hominids, and that we are humans, and like the majority of all these groups we are adapted to a plant-based diet. They tell us that we are mostly frugivores, like most primates and most apes, and although the fact we can cook has increased the types of food we can now eat (including meat), we remain anatomically frugivores (adapted to eat fruits and nuts).
Our teeth don’t tell us everything about our diet, though. They don’t tell us that we can now also eat all sorts of leaves, grains, roots, fungi, algae, fermented foods and starch-rich vegetables — but other parts of our anatomy and physiology tell us that we can — but they do suggest that we have found other ways to break hard nuts and soften tough plants without using our teeth (namely, cooking). And our teeth do not tell us either about the philosophies we have adapted, our ingenuity to find solutions, and the ethics that govern our behaviour — which would make us find a way to overcome any biological obstacle to veganism, if there were any.
The number, size, and shape of our pointed teeth, and the small size of our canines, all point away from a carnivore adaptation, so a vegan sceptic pointing at them and saying “canines, though” is as much as a bizarre failure to argue against the vegan lifestyle as it would be to point to a vegan restaurant and say “vegetables, though”. Debunking this remark does not require complicated arguments and lots of data. It only requires understanding what canines are and what they do, and looking at our mouths and comparing them with those of truly carnivore animals (have a hard look at the photo above showing the skull of a human by the skull of a wolf).
If alien palaeontologists landed on Earth in the future after humans became extinct, while other mammal species survived, and only found the jaws of fossilised humans (as we have only found the fossilised jaws of the first mammals), I am sure they would unequivocally conclude that Homo sapiens was not a carnivore species, and they could well deduce that we were frugivores, like the other apes — if there were any left alive to check what they eat.
No other part of our body would give better information about what humans are adapted to eat than our jaws (with all their teeth), so if, playing a strange party game, I was asked to prove without using any words that being vegan is natural for humans, I would simply point at my teeth, as it is the strongest piece of evidence that we don’t have a carnivore adaptation and that the diet of vegans is not unnatural to us from a biological point of view. This is why it baffles me when the “canines, though” remark is used to try to prove the precise opposite.
I guess I should put it down to ignorance.
