I am trying to design a species. Members of these species can run most efficiently in quadrupedal. If possible, they should press on their palms, not knuckles.

They can also walk upright like humans do in bipedal form. They can use their hands skillfully like humans do. Their upright posture shouldn't be so different from humans. Also their upright height must be somewhat close to human height.

What should I regard when designing such a species? I realized that bone and muscle structure, also the body proportions have a big effect on how a species walk and run. I am looking for science based answers and real life examples.

  • 1
    $\begingroup$ Look at bears for the proportions $\endgroup$
    – DonQuiKong
    May 11, 2017 at 7:37
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    $\begingroup$ So, Chimpanzees? $\endgroup$ May 11, 2017 at 7:37
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    $\begingroup$ You should have a look at Gorillas. They do knuckle-walking which looks like it fits exactly what you are looking for $\endgroup$
    – Secespitus
    May 11, 2017 at 7:40
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    $\begingroup$ If they can walk upright like humans, as opposed to wobbling around like apes on two feet, then running upright is going to be more efficient than on all fours. A human can run down a horse or antelope over time. It's a hunting method that some still use. $\endgroup$
    – Kilisi
    May 11, 2017 at 8:30
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    $\begingroup$ You need to specify how your creatures differ from apes, other than palm-walking instead of knuckle walking. Otherwise, the answer to your question is: design an ape, and it is unclear what you are asking. $\endgroup$
    – kingledion
    May 11, 2017 at 12:25

2 Answers 2


Your alien cannot be anything like human in terms of physiognomy. Humans are made for bipedal running, we cannot run on all fours at any sort of reasonable speed. So you'll have to look at what needs changing.

Start from the top, our heads sit above our spines. other animals don't because they need to see what is front of them on all fours. (Humans on all fours in natural posture are looking at the ground, we need to strain our necks to look ahead.)

The shoulders and arms are not built for running, you need to spring load you aliens somehow and have the arms go under the body to support weight efficiently, not out to the sides.

Spines I guess you'd have to change, and hips and legs, you'd want to change the whole way these works somehow, and either shorten the legs or have them fold on themselves somehow.

Apes have this, they can run on all fours by having much shorter legs in comparison to their long arms, so they keep their heads up easier etc,. So mmodel your aliens after chimps or baboons as a base, rather than a human. Then you just need to get the bipedalism working efficiently.


According this answer you should think about balance between speed when running in quadrupedal and ability to use hands like humans.

As other people note, there are many examples in our world:

  • bears
    • pandas (my favorite) able to climb up but slow at run
    • polar bear could swim and sprint up to 40 km/h but couldn't climbing
    • Grizzly is in a middle: climbs up worse than panda and travels for a fewer distance than polar bear
  • primates
    • gorillas
    • chimpanzees
    • etc

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