pls disragard these questions if you arent feeling like explaining anthropology that is probably not within your specific field, but i have questions and somehow youre the most accessible source for answers about ancient-ass humans. so: why are humans so much hardier than other animals? like if you break a horse's bone that horse is kaput, but people bounce back from shit like missing limbs. how are we so cool? also, how prevalent (and when) was pursuit predation? also, thanks! have a nice day
OH no worries, this is something I teach every year and it’s REALLY COOL. There’s footnotes and works cited below the jump if you want them, and I can point you at some other work if this is something you’re interested in reading about.
Humans are ridiculously resilient. The reason for this has a lot to do with the tradeoffs we made for endurance rather than speed. Human walking is really energy efficient (it’s really just controlled falling) compared to a horse’s galloping, and we have pretty well-muscled legs. Our plantigrade feet mean that there’s not as much energy when we spring off compared to an animal that runs on their toes, but at the same time, we spend a lot less energy moving around.
Our muscles and leg anatomy have a lot to do with it, too. Let’s look at a horse’s leg compared to a human’s.
Horses in particular have a hard time with broken legs because they have a LOT of mass resting on on those legs. Horses’ legs are basically built to go fast- their leg bones are actually quite light, and below the ankle there’s… well, basically nothing. Just tendon and skin- there’s no big muscles to stabilize or cushion the bone. This means that there’s less weight to drag around so the horse can escape a predator more quickly, but it comes with a major tradeoff- if a horse breaks their lower leg, it tends to shatter. In the wild, this is going to make the horse extremely easy to pick off. But like I said up there, humans- unlike horses- don’t run on our toes. Our ankle bones are chunky and strong, and our lower legs are cushioned with muscle and fat.
But our healing ability goes beyond just basic anatomy! Our group dynamics also play into this, too. If a horse breaks a leg, what can the other horses do about it? The injured horse still has its biological needs to fulfill; it has to eat, drink, and evade predators. It has to keep moving- it can’t lie down for a few weeks and let the leg heal. But that’s not true of humans and our closest relatives! I’ll use Neanderthals for this example because I like them a lot, but the same goes for early modern humans, too.
Let’s say that some Neanderthals are out on the hunt, and Thog gets knocked against a tree trunk by a mammoth and she breaks her leg. Because Thog’s a member of a social species, it’s not the end of the world for her or her group. The rest of her crew can keep hunting and Thog can limp back home, where her grandfather looks after her and her younger sister brings her water. She’s able to rest and keep weight off the broken leg, which means that so long as she keeps whatever wounds there might be relatively clean, sepsis is less likely. Group living means that you don’t have to be self-sufficient; no hominin is an island. Part of why we’re so successful is that our ability to care for each other ensures better group survival. If your reproductive-age individuals are also providers, group care means that you’re less likely to lose them.
We know from looking at Neanderthal skeletons that they were injured frequently and were able to shake it off and survive; even elderly individuals with severe arthritis are often found in group contexts, suggesting they weren’t left behind. And we are talking serious injuries here- not just broken legs, but head and neck trauma, too. There’s a famous paper* that says that most Neanderthal injuries came from close contact hunting (due to them being mostly head and neck injuries rather than lower body injuries), but more up-to-date research notes that actually, Neanderthals could- and did- get hurt pretty much everywhere**.
As to when pursuit predation came into effect, the best guess we have is “probably sometime around two million years ago, practiced by Homo erectus/ergaster.” One way we can tell this is by diet. Mandibles are very quick to adapt to dietary pressures, so by comparing mandibles to things with known diets, we’re able to tell what’s going on. Add that to dental wear and morphology studies and chemical analysis of subfossils’*** teeth and we can get a pretty good picture of who’s eating what. What we see with the H. erectus/ergaster complex of species is that they’re eating a wide variety of very tough foods; their jaws and molars suggest that they were eating root vegetables, tough meat, tubers, bone marrow, honey- really, anything they could find. We also know that they were eating a fairly high calorie diet compared to their predecessors; this was necessary for brain development- and we know that these calories came from meat. As average brain mass increases, so does evidence of meat-eating. Brain development is expensive- you have to put a lot of nutrients into it- nutrients that are really hard to get from plants alone. One way to feed the family is by hunting- though realistically this didn’t happen all that regularly. Rather, it’s more likely that hunting supplemented gathering, as it does with many forager groups today; hunting takes a lot of energy and can be dangerous.
Archaeology also points to the “around two million years ago” date based on stone tool deposits and fossil prey species. One good example of this is Kanjera in Kenya; it’s a site by Lake Victoria that has good evidence for persistence hunting. There’s quite a lot of gazelle and antelope skeletons that aside from stone tool marks, don’t have a lot of damage. It looks like these were brought to the site for butchering- and they would have had to be hunted because hyenas, lions, and other predators and scavengers will actually eat those bones. Gazelles are a lot faster than humans, and the hominins of the time didn’t really do projectiles; rather, it’s more likely they ran the gazelles down until they were exhausted, then dragged them back to this lakeside camp site to process and eat. It’s likely that this strategy helped fuel the migration of Homo into Asia; once you’re able to hunt big game, your movement is less restricted by the availability of small animals, scavenged meat, and seasonal plants; you can follow herd animals and just chase one whenever you need to eat. However, the exact role that hunting and scavenging played in the development of the Homo genus is something that archaeologists and physical anthropologists do not agree on- when you’re trying to figure out what a species eats and how they got their food, you gotta realize that this can vary heavily by what’s available, what predators are in the area, your own group’s composition, and myriad other factors that can affect food acquisition.
One thing we do know for sure: Persistence hunting works. Our species is super good at it, even today. If you’d like to see some persistence hunting in action, it’s actually still used by San groups in Africa.