Evolution

The human body was not built to hunt

By WhyStopHarmingAnimals.com

Nothing in the human body can bring down a large animal and open it up[1][2]. Our nails are thin and flat and do not go through fur, hide, feathers or connective tissue[1]. Our teeth are short and blunt next to a cat's[1]. A lion needs only its own body to kill a deer and eat it[2], while a person needs a sharpened edge, a weapon[2] and, in practice, a fire[3]. Go through the jaw, the eyes, the skin and even the way people react to a dead body, and the same animal keeps turning up: a daytime primate that forages for plants and learned to make tools.

Teeth, jaws and nails

Milton Mills, a physician who has compared the eating anatomy of mammals, sets out the differences[1]. A cat has carnassials, blade-like cheek teeth that scissor through flesh and tendon, and its jaw is a hinge that moves up and down with almost no sideways play[1]. The human jaw joint sits above the tooth row, and a disc lets the lower jaw slide forward and from side to side, which is how molars crush and grind[1]. Our incisors are spade-shaped. Our canines are small and blunt and work more like extra incisors[1]. Our molars are squarish, bumpy and closely packed, closer to grinding stones than blades[1]. Where a cat has claws, we have flat nails[1].

Mills's comparison matches what dentists see every day[1]. This mouth is built to pulp plants, and it cannot shear a hide[1].

Tools first, then the kill

Humans can and do eat meat, so the useful question is what the body brings to the job on its own. The Smithsonian's Human Origins program notes that early humans used stone tools for more than 2 million years to cut, pound and crush food, including meat from large animals[2], and that wooden spears for killing large animals appear around 500,000 years ago[2]. Those dates are often cited as proof that we were meant to eat meat. What they record is how much equipment the job took[2]. Without a manufactured edge a human cannot open a hide, and without a spear a human cannot take down a cow[2].

Eating the animal took more technology again[3]. The biological anthropologist Richard Wrangham treats cooking as a human biological trait[3]: many plant foods are too fibrous to eat raw[3], and most raw meat is too tough to chew easily[3]. Heat is what made flesh workable for our teeth[3]. Then comes flavor. The Institute of Medicine's 2010 report on sodium notes that added salt improves the taste of nearly every food people eat[4], and that without it food often tastes bad[4]. Unseasoned meat is mostly bland[3][4], and the herbs, spices and sauces that do the rest of the work are plants[3], the same ones used to season meat substitutes. Killing, skinning and enjoying an animal all depend on tools and a kitchen[2][3][4].

The eyes and skin of a daytime forager

Old World monkeys, apes and humans see reds and greens[5]. In a 2001 paper in Nature, Dominy and Lucas argued that this trichromatic vision helps primates find ripe fruit and young red leaves against a green canopy[5]. Dogs see the world differently[6]. Behavioral tests by Neitz, Geist and Jacobs found that dogs have two cone types instead of three, which gives them blue-yellow color vision without the red-green contrast we use to spot a berry, and cats are similar[6]. So carnivores do see some color; they just do not see fruit the way a primate does[6]. We also lack a tapetum lucidum, the reflective layer behind the retina that gives cats and dogs eyeshine and better night vision[7]. Haplorhine primates, the group that includes us, are active by day and sleep through the dark[7].

Our eyes also give us away. Human sclera is unusually white and exposed, so anyone nearby can tell where we are looking[9]. Kobayashi and Kohshima described this[9], and Michael Tomasello's cooperative-eye hypothesis holds that it helps people share attention and work together[8]. A 2022 study in eLife by Kano and colleagues found that uniformly white sclera helps both humans and chimpanzees read gaze[9]. A stalker gains by hiding where it is looking, and humans advertise it[9].

We cool off like a forager too[10]. Humans shed heat through eccrine sweat glands spread across the skin, a trait Best and Kamilar (Journal of Human Evolution, 2018) trace to the catarrhine primates and find expanded in us[10]. Dogs and cats have few of these glands and cool by panting, evaporating water from the tongue and mouth[10]. The other well-known sweaters are horses and some other primates, and both eat plants[10]. Sweating over the whole body suits an animal that keeps moving through the heat of the day while it gathers food[10].

The two traits most often held up as signs of a hunter, forward-facing eyes and canine teeth, are ordinary primate features. Every monkey and ape has forward-facing eyes, and gorillas, geladas and orangutans carry canines far bigger than ours while living on leaves, grass and fruit.

The first reaction is to pull back

Ask people whether they would hurt a dog, a cow or a chicken with their own hands, and most say no. In a 2023 Pew Research Center survey, 97% of U.S. pet owners said their pets are part of the family, and about half said they are as much a part of it as a human member[13]. The psychologists Loughnan, Bastian and Haslam (Current Directions in Psychological Science, 2014) call the conflict between caring about animals and eating them the "meat paradox"[14]. People manage it through motivated disengagement: they deny the animal a mind, keep the body out of sight and rename the dead animal as food[14].

That work is needed because a carcass does not look or smell like dinner to most people[14]. It takes a butcher, a stove[3] and a new name[14] before it does, and without a weapon most of us could not take the animal down in the first place[2]. An appetite for steak is often an appetite for a story told after the blood has been rinsed off.