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Exactly what it says on the tin: would having prehensile feet with human finger-length toes impair running, walking, jumping, or other foot-based activities in a human?

Presume that, when carrying out activities that aren't grasping things, this person bends their toes upwards at their joints, and those joints are what touch the ground; this stops the rest of the digit from getting in the way.

Those joints can be somehow biologically reinforced if necessary for the purposes of a better answer; I can imagine that putting repeated stress on an unreinforced joint isn't too good for it.

Imagine that they can also bend back at a 90-degree angle relative to the rest of the foot to avoid ground contact.

Additionally, presume that they've grown up this way since birth, and that they don't need to adapt to it.

EDIT: The feet have opposable thumbs.

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  • $\begingroup$ With or without opposable thumb/toe? $\endgroup$
    – L.Dutch
    Nov 2, 2021 at 8:42
  • $\begingroup$ @L.Dutch With them. $\endgroup$
    – KEY_ABRADE
    Nov 2, 2021 at 8:42
  • $\begingroup$ Lots of species of monkeys have prehensile feet, and most of them are faster runners than humans as well, so it seems like they're not a problem at all. $\endgroup$ Nov 2, 2021 at 17:05

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A foot with longer toes will be less energetically efficient, unless the toes are strong enough to contribute to the gait.

At walking speed the difference will be utterly trivial. Literally only the effort needed to move the additional mass of the longer toes and the additional calf muscles required to manipulate them.

Maximum top running speed will be significantly reduced, simply because there is more mass at the end of the feet that needs to be rapidly moved around. Same thing as running in heavy shoes vs. running with light shoes, even if the heavy shoes are exactly as flexible as the lighter ones.

All in all there will be a real reduction in the walking efficiency, but it will be small and roughly proportional to the added mass of the toes and their controlling bones and musculature. Definitely not a showstopper.

Potentially of more concern is the damageability of the handy feet. By being at the end of a longer and heavier limb that is also bearing your full weight, and by being less conveniently located in front of the eyes than your hands, these handy feet will be subjected to more frequent and higher impact accidental knocks than hands are(compare how badly you stub your bigtoe, compared to how often and hard you stub your thumb, even though you use your thumb a lot more often). They will need to be sufficiently protected, or be sufficiently robust to not mind such treatment.

You should be able to jump a bit further, and much more accurately, due to having better dexterity and enhanced tactile feedback and more complex muscles controlling the handy feet.

And your climbing ability will be astronomically better. Much more than just twice as good.

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  • $\begingroup$ Gosh I just tried to imagine what it would be like jumping across a gap and grabbing a rocky ledge on the other side with my feet and feels weird. $\endgroup$ Nov 2, 2021 at 9:28
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    $\begingroup$ Think of what masters of Parkour these would be. Almost as fast as a normal skilled human, better jumper, and can grip at both ends. Can hang upside-down from the edge of a roof. Can simultaneously grip two posts up to 10 feet apart! $\endgroup$
    – PcMan
    Nov 2, 2021 at 9:32
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Racoons have a similar anatomy to what you describe, and they don't seem to be hindered in their abilities.

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The main hurdle would be that, due to bipedalism, the size of the ball of the foot, needed to help holding the weight of the body, would limit the holding capability, but that's not what you are asking.

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