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Notorious_Rug t1_iwp24a0 wrote

Gorillas use columnar knucke-walking, where the wrist and hand joints are aligned in a relatively neutral, straight position, which helps with weight bearing. Gorillas are not as arboreal (tree-dwelling) as chimpanzees, so their form of knuckle-walking evolved to maximize terrestrial movement, as well as the aformentioned weight-bearing.

Chimpanzees knuckle-walk with extended wrists, which is due to the fact that they, like most primates, extend their wrists to preserve their balance while engaging in arboreal activities. Due to this need to extend their wrists to preserve balance and protect themselves in an uncontrollable fall, the chimpanzee's wrist bone anatomy has evolved to differ from that of a gorilla, which results in a different form of knuckle-walking.

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xDaBaDee t1_iwpj52p wrote

Replying to Notorious_Rug (#552,528)

I am going to add my two coffee cup cents to this user's oh so very words on wise. I would think weight and size would affect this.

I would also suggest OP check out, if interested in the same topic, the info on horse movement. I watched one that explained and showed how when horses run there is a moment when all four hooves are not touching the ground. It was interestingly informative. Now back to my regular coffee cup consumption.

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LemursRideBigWheels t1_iwpk1mz wrote

Replying to DellSalami (#553,291)

Think a vertical orientation of the hand vs a more canted orientation of the hand. Neither ball their hand up or place their palm on the ground while locomoting — they use the middle set of knuckles for support. Interestingly, what you describe is somewhat akin to what’s seen with orangutans when on the ground or arboreal monkeys respectively.

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sharaq t1_iwpm15q wrote

Replying to xDaBaDee (#553,310)

Why would it surprise you that all four legs do not touch the ground? That's how everything runs. Even the running emoji features someone at that moment in their stride.

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merrycat t1_iwpvn42 wrote

Replying to xDaBaDee (#553,310)

I was really surprised to find that moment of suspension wasn't when the legs were all outstretched, but when they were gathered under the horse, just before the hind legs touch down.

Some dogs have a double suspension gallop which is more what Iwas expecting. All four legs are off the ground when gathered under them, and again when they're all stretched out.

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bwyer t1_iwpyknb wrote

Replying to outboxtheside (#553,019)

Thank you.

Of course, I was promptly forced to recreate the position with my own hands to really figure out what was going on. The diagrams were quite helpful.

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mtx013 t1_iwqa2bs wrote

Replying to sticksnstone (#554,569)

Thats not an arm, the image shows a profile picture of wrist/hand/fingers, but your point stands.

For reference, use your own anatomy: the bone they use to touch the ground is the middle bone of your fingers (thumb excluded) and the finger tip is curled up. From there we have the finger first bone (slightly bent), hand bone (big one), two wrist bones and just the end end of forearm bone.

The main difference between the two species is how the forearm-wrist, wrist-wrist and wrist-hand articulations are used. Chips bend them and gorillas use then in a straight line.

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Tiny_Rat t1_iwqabou wrote

Replying to merrycat (#554,115)

The dogs that run like this have much more flexible spines than horses, and are also much lighter for their height. A horse doesn't have enough flexibility and power to run like that.

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sharaq t1_iwqel7h wrote

Replying to factfarmer (#554,443)

>with most gaits

Yes, and with most gaits, a human likewise maintains contact with the ground, but those gaits are not a "run" or appropriate equivalent (gallop).

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Key-Seaworthiness764 t1_iwqq75l wrote

Lemursride is correct with the middle knuckles. Like a karate chop but you curl just your fingers in half. That is the difference between the two' walking with knuckles though both can, and do use both technique' if motion dictates it.

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Snarlio t1_iwr1yja wrote

Replying to Notorious_Rug (#552,528)

I think it's also worth noting that the clavicle (collar bone) of arboreal apes is different than that of terrestrial apes. Gorillas have a more "C" shaped collar bone, which allows for a lot more force to be applied to the sternum and rib cage without the bone breaking. This lets them put a lot more weight on their arms safely.

Chimpanzees have an "S" shaped clavicle, which is not nearly as efficient in transferring force, but allows for a lot more mobility for brachiation (swinging through trees). It's the same reason that people can break their collarbones when they fall face first and use an outstretched arm to break their fall - we also have "S" shaped clavicles.

Found this after a quick search: https://doi.org/10.1002/ar.a.20354 Figure 2 shows the bones in question

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waterslidelobbyist t1_iwr9rvz wrote

Replying to FillRevolutionary900 (#557,287)

We share a common ancestor with chimpanzees more recently than with gorillas. Either the mutation to a more gorilla-like clavicle hadn't happened or was not enough of an advantage to be selected for as we evolved away from proto-chimps.

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FillRevolutionary900 t1_iwrab2v wrote

Replying to waterslidelobbyist (#557,556)

But that makes the statement distinguishing the terrestrial apes and arboreal apes in terms of the shape of their clavicles meaningless. Because there are really only two terrestrial apes (gorillas and humans), and one of those two doesn't fit what the statement claims. So why make that distinction in the first place.

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Ameisen t1_iwrcnq9 wrote

Replying to dmnhntr86 (#554,431)

Apes are monkeys - they're a clade within the catarrhine monkeys. A fairly deeply-originating one at that.

There's no way to define monkeys with apes not being included without being quite paraphyletic.

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CeaRhan t1_iwrfc57 wrote

Replying to DellSalami (#553,291)

The gorillas keep their hands/wrists straight to do something similar to what our legs do/look like while doing it, because they're essentially using them as front legs and they need to make sure they won't break/damage their wrists. So they essentially do the second picture here and put their knuckles on the ground.

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waterslidelobbyist t1_iwrkjyx wrote

Replying to FillRevolutionary900 (#557,601)

I'm honestly not smart enough to explain the distinction but I'll try. We're one of the two terrestrial apes now, but in the Miocene we've got a whole grip of weird apes running around Africa and Eurasia on the ground, and they're all more closely related to gorillas and have similar adaptations.

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wi_voter t1_iwrz4uv wrote

I have to jump in with an FYI. The reason humans do not have to knuckle walk is because our pelvic bones are oriented more in the frontal plane while other primates have their pelvic bones oriented more in the sagittal plane. Our frontal plane orientation allows us to successfully stand on one foot when the hip abductor muscles contract on one side and keep the pelvis from falling on the other side like a seesaw.

Jumping in because years ago in college I got to assist in the research on the hip abductor muscles and their role in unilateral stance and gait. This was always one of my favorite little factoids from those days. :)

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updn t1_iwsa8tm wrote

Replying to wi_voter (#559,347)

It seems pretty well established that humans evolved to be runners. I can almost visualize the transition to a more upright stance and balance as we get into more of a gallop

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Ameisen t1_iwsbdu8 wrote

Replying to webbphillips (#559,086)

Reptiles are diapsids, while mammals are synapsids. Though it depends on your definition of "reptile", though when amniotes first appeared they very rapidly split into synapsids and diapsids, while apes appeared 10 million years after the first Cattarhines (and aren't significantly different from their closest non-ape relatives).

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Fayko t1_iwsfbic wrote

Gorillas are built to be more thicc and walk more with them baby bearing hips than their fingies.

Chimpanzees have had spinal issues for so long they got chineese grandma backs so gotta shuffle their weight more to their back and hands.

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Ameisen t1_iwsnowq wrote

Replying to kfederal (#560,971)

All the mitochondria in all Eukaryotes are the descendents of a single proto-mitochondrion (likely closely-related to Rickettsoid bacteria) which was engulfed by an early proto-Eukaryotic cell, but was not destroyed.

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MrInfinitumEnd t1_iwst5pd wrote

Replying to Notorious_Rug (#552,528)

>extend their wrists

What? What does this even mean?

>which is due to the fact that they, like most primates, extend their wrists to preserve their balance

the 'extend their wrists' here is unnecessary and doesn't make sense.

'which is due to the fact that they want to preserve their balance' is better.

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Norwester77 t1_iwt0whv wrote

Replying to FillRevolutionary900 (#557,287)

We don’t seem to have gone through a knuckle-walking stage (the ancestors of gorillas, chimps, and humans became terrestrial independently of one another), so our clavicles never had to support much body weight.

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Norwester77 t1_iwt1d2v wrote

Replying to DellSalami (#553,291)

No, both species knuckle-walk with the hands curled and the middle bones of the fingers on the ground. Chimps knuckle-walk with their wrists bent, but gorillas knuckle-walk with their wrists straight.

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junegoesaround5689 t1_iwt1e65 wrote

Replying to updn (#560,177)

The upright stance developed more than a million years before adaptations for long distance running. The running adaptations happened around the homo erectus timeframe ca 2 million years ago. The bipedal/upright adaptations occurred in the ardipithecus to australopithecus timeframe ca 4.5 to 3 million years ago with some going back even further.

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