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Lets say, in an alternate timeline of hominid evolution, humanity (or at least some kind of human-like species) evolved for a strictly carnivorous diet, like true carnivores. What changes would need to occur in our evolution (let's say starting from Sahelanthropus) for a human species to emerge that's strictly built for a carnivorous diet, like that of tigers or polar bears? What differences would they have from us modern humans for the sake of being true carnivores? If every stage of our evolution starting from about 10 million years ago were to bring us to a carnivorous species, what would that look like?

So far, I've come up with the following possible traits: Long, strong legs for running and chasing (or even the ability to alternate between being on 2 legs and all fours when chasing prey), possibly sharpened finger nails/claws, a re-emergence of giant primate canine teeth (this time with sharpness), a shortened digestive tract (a common trait of carnivores), a skeletal-muscular system mostly consisting of fast-twitch muscle fibers (high power, low endurance, similar to a feline species) and possibly a different setup for mounting muscles on our jaws (something more akin to a carnivore like a Tiger, an offshoot of the sagittal crest paranthropus had). Would this species still even be capable of evolving into a sentient hominid race like us?

I still want earth to be the same gravity and atmosphere as it is now, but the actual environment (what kind of possible modern natural ecosystem this species grows in) can be as variable as it must be for this hypothetical species to work. I know Earth's climate has changed since the days of Sahelanthropus, but as long as the range of habitats and environments Earth has by the age of our fully-evolved carnivorous human ends up like ours (industrialization included if necessary), I'm all in.

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    $\begingroup$ (1) It's hom-i-nid, not **hom-o-nid. (The stem of the Latin word homo "human being without distinction of sex" is homin-.) (2) Humans are megafauna: we are large animals. The largest most striking difference that strict carnivory would induce is that there will be very very very few humans, and they would have a very limited distribution. (3) Primates have entirely the wrong body plan for a strict carnivore. (4) With so very few humans there is no hope of ever getting out of the stone age, let alone reaching the age of machines. $\endgroup$
    – AlexP
    Feb 28, 2021 at 9:30
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    $\begingroup$ Humans already have long, strong legs for running and chasing - specifically for overrunning our prey, in fact. As such, fast-twitch muscles would be a detriment, not an asset - we need endurance to do that overrunning. There are many ways to hunt, not just ambush predation. $\endgroup$
    – No Name
    Feb 28, 2021 at 9:46
  • $\begingroup$ Does this answer your question? worldbuilding.stackexchange.com/questions/4778/… or this? worldbuilding.stackexchange.com/questions/194818/… $\endgroup$
    – DWKraus
    Feb 28, 2021 at 13:38
  • $\begingroup$ @AlexP I believe OP was referring to members of the family "hominidae", in which case "hominid" would be correct. $\endgroup$ Feb 28, 2021 at 18:59
  • $\begingroup$ This question ought to be merged with the one it duplicates. $\endgroup$
    – elemtilas
    Feb 28, 2021 at 19:51

2 Answers 2

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Your species would look like a human

Point blank, hominin hominids, specifically members of the genus Homo, are about as close as Primates have ever gotten to producing a specialized carnivore. Homo sapiens and Homo neanderthalensis are actually some of the most carnivorous primates ever aside from the insectivorous tarsiers. Researchers have actually described our genus as the primate attempt to create an apex predator.

In fact, our carnivorousness is what allowed us to spread across and conquer the world and avoid the fate of all other Primates. Primates have been heavily constrained by the abundance of fruits and nuts due to that being their primary food source, and as a result their fate follows that of the tropical forests (and they've been doing pretty poorly since the Eocene). Except humans, who became carnivorous and now could go anywhere because meat is a food present in all corners of the globe. Look at our diet. Human beings can only eat a very limited range of foods. We can only tolerate about two dozen species of leafy vegetables, compared to other primates that can eat hundreds. The rest of our diet is composed of fruits, nuts, grass seeds (wheat, rice, corn), and starchy underground tubers. And meat. Lots and lots of meat. Meat is the one food source where we have lots of options to eat. We can't even handle as many fruits and tubers as other primates because they're poisonous to us. Baboons are known to eat cycad fruit whereas humans can't touch the stuff without extensive processing. If we weren't predators we would still be stuck in tropical Africa.

Technically we're hypocarnivores, like bears, with about 40-60% of our diet being meat, but we still fill the niche of a bear-like predator (which is one reason why bears have fared the worst against humans when we enter a new habitat).

Many human cultures can even be strictly carnivorous. Like the Inuit or the Mongols.

Lets also look at the traits you've listed.

  • Long, strong legs for running and chasing

We already have that. We're not fast but have great endurance.

  • A shortened digestive tract (a common trait of carnivores)

Already have that. We lack the large caeca, extensive intestines, and/or multi-chambered guts of gorillas, atelids, and colobine monkeys, not to mention our more omnivorous relatives (whose guts are still longer and more complex than ours). Also Homo has reduced cheek teeth compares to their relatives, which is another carnivore trait.

  • Possibly sharpened finger nails/claws, a re-emergence of giant primate canine teeth (this time with sharpness), a skeletal-muscular system mostly consisting of fast-twitch muscle fibers (high power, low endurance, similar to a feline species) and possibly a different setup for mounting muscles on our jaws (something more akin to a carnivore like a Tiger, an offshoot of the sagittal crest paranthropus had). Would this species still even be capable of evolving into a sentient hominid race like us?

All of this seems to be missing the point as to why humans are such effective predators in the first place. Humans aren't successful predators because they chase their prey down and beat it in a fistfight. We're good predators because they have high endurance, good binocular vision, and good hand-eye coordination, which lets us bombard prey from a distance with rocks, slings, arrows, and atlatls until it dies. Just because they don't hunt the same way other animals do doesn't mean they're bad predators. It's a different kind of predation strategy, but it works. In fact, it works really, really well, because almost no animal has a good answer to a predator that attacks from range. Look at the ground sloths, who were OP in melee combat due to their combination of fast reflexes, robust builds, dermal armor, and thick skin and fur. They were average in straight up speed, but that didn't matter when you could break a Smilodon over your knees with your bare hands. That is, until humans showed up and made a mockery of ground sloths by exploiting their lack of agility or ability to respond to ranged threats. We actually have fossil trackways of humans playing keep-away with ground sloths.

The trade off to this is we're not super fast and we're screwed if something catches us off-guard without prep time.

Also a bit of a tangent, but Primates already have sharpened canine teeth. Primate canines are sharper than tiger or bear canines. Hominins are just unusual among Primates in having secondarily lost them.

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They would look like this, apparently: Derek Nance

This Guy's Eaten Nothing but Raw Meat for Five Years


But onto the meat of your question:

Long, strong legs for running and chasing (or even the ability to alternate between being on 2 legs and all fours when chasing prey),

We've already got excellent legs for running and chasing. Sure, we can't outrun many prey species, but it turns out we're still pretty good at endurance hunting.

possibly sharpened finger nails/claws, a re-emergence of giant primate canine teeth (this time with sharpness)

Seems unnecessary. Even now, we can see that other primate species like chimpanzees, who like a bit of fresh meat from time to time, can hunt and kill monkeys without the need for claws or massive sharp pointy teeth.

Chimpanzees eating a monkey

A few relevant videos:

a shortened digestive tract (a common trait of carnivores)

This might actually be plausible, but consider that an obligate carnivore might have serious problems coexisting with an intelligent omnivorous species that might have access to much more food sources in difficult times and would perceive their cousins as a threat.

a skeletal-muscular system mostly consisting of fast-twitch muscle fibres (high power, low endurance, similar to a feline species)

This runs directly counter to our already practical high-endurance, low-speed setup which turns out to work OK.

possibly a different setup for mounting muscles on our jaws (something more akin to a carnivore like a Tiger, an offshoot of the sagittal crest paranthropus had).

Maybe. It isn't obviously necessary... remember that animals like tigers use their jaws as a weapon and so need quite radically different neck and head musculature. Surely your proposed hominids would be using different techniques? (see also: chimps hunting monkeys).

Would this species still even be capable of evolving into a sentient homonid race like us?

We don't really have enough to go on to answer that question. I would suggest, though, that such a species would be unlikely to coexist with Homo Sapiens or its forebears, and we know what happened to the other flavours of hominid that used to live on this planet, don't we?


Consider that one can be a carnivore without being a hands-on predator. A sufficiently clever and organised scavenger species could conceivably drive off dangerous predators and steal their kill. Humans have certainly done this in the past. The ability to craft weapons would certainly help, but even the ability to throw rocks effectively is a trick that is vanishingly unusual in the animal kingdom.

See also tricks like this, where one can use brains to kill large, fast and dangerous (but above all, tasty) megafauna without having to evolve into a tiger.

Acquiring sufficient calories this way might be tricky, but evolution isn't required to act in the long-term best interests of any species, and a previously omnivorous species evolving into an obligate carnivore due to some unfortunate mutation, population bottleneck and genetic drift could conceivably distribute the deleterious mutation through an entire population forcing them to become meat-eaters even if they weren't previously.

This could explain your species, though it would come with almost none of the big-bad-predatory-physique changes that you seem to want. Sorry about that.


For a different take though, have a search for Peter Watts' take on vampires. He has some interesting ideas there which may be of interest to you.

Irritatingly, I can't find a succint summary of his ideas, but there is a youtube version of a fictional lecture he produced on the subject, if you were bored.

His vampires were hominids that preyed on other hominids (for reasons that are explained in universe that I won't repeat here)... they were very strong, certainly, but primarily they were very intelligent, as would be required for hunting intelligent and social prey. They were also hibernatory, making it easier to lie low between meals, and avoid stirring up too much trouble in local human societies.

Its not quite what you're after, but interesting nonetheless.

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  • $\begingroup$ My neighbor Jacob (or Jakob, i think.. shrug), is a carnivore. Eats meat, the whole meat, and nothing but the meat. Give the man a hamburger, and he will politely remove the bun, garnish, wipe off all sauces, and eat the meat. And complain bitterly if you put onion in the meat mix! He also eats eggs, but that's just another form of meat, hm? p.s. Don't walk downwind from him. For some obscure reason he has both bad breath, nasty BO and farts-from-hell. $\endgroup$
    – PcMan
    Feb 28, 2021 at 10:13
  • $\begingroup$ @PcMan it is an extremely inefficient way to feed a human, too. Selfish and environmentally destructive. It is almost enough to make one invest in a bit of applied Alpha-Gal research... $\endgroup$ Feb 28, 2021 at 10:20
  • $\begingroup$ @PcMan The smells are because his intestinal biome is having to deal with the meat and byproducts. The rest of us have a biome that is more geared towards plants. Note: when the Lewis and Clark expedition reached Idaho, they ate roots that "filled us with such wind that we could hardly breathe." They had been living on meat till then. $\endgroup$
    – David R
    Feb 28, 2021 at 16:22

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