How might digitigrade races in a predominantly plantigrade society cope with the problems that come with structures not being designed for them?

Question

In my fantasy/sci-fi/speculative writings, I have several digitigrade beings. The Salamandrion (whom I've talked about before) are one of them, but the Argonite and Drachenheul races, displayed in this drawing, also have this foot structure:

I apologize for my mediocre art skills, but this is the best I can do. While looking over my designs, and also walking around on my tiptoes for a little while/studying my dog's paws to try and gauge what it might be like, I realized a bit of a problem. These creatures most likely have a strange center of balance compared to us humans, which, in my testing, causes some trouble on stairs, for example. Now you might say, "Well, they just never came up with stairs then and just used ramps or ladders, or just flew (in the case of the winged species)" and this makes sense for the architecture on Drachenwelt or Australis or one of the Drachenheul or Argonite-controlled planets, but they aren't the only creatures in the galaxy and they aren't restricted to those planets. The vast majority of the sapient races are plantigrade; Humans and Ailurids, both of which have a plantigrade foot structure, are behind much of the design world in this universe, and thus create most of their buildings, vehicles, devices, etc. with human-like feet in mind. There's no real pressure for this to change, at least not yet in the time period the story happens in (the equivalent of the late 1960's). Elevators exist if you're wondering, but you can't put an elevator just to go up a couple feet to someone's house that's elevated off the ground, and what about places without electricity but with a mixed-species population?

All this to say, what would a digitgrade being have to do to go about life in a world clearly not designed for his body shape?

Answer 1

An Important Point

When I saw @Escapeddentalpatient.'s comment and @Kilisi's answer I decided to convert my comment to an answer, because you've solved your own problem — you just don't realize it.

Let's start with You Can't Climb a Mountain With Ostrich Legs. You can't! The lean-forward push-up motion needed for climbing a reasonably steep incline can't be accomplished with a digitigrade Ostrich leg. But there's something you need to consider.

The Ostrich leg has two major joints. Let's call the upper one the "knee" and the lower one the "ankle." See how they're designed? Any effort to climb an incline of more than a handful of degrees would cause the bird to topple over backwards. The rotation motion of the "hip" allows it to move forward (which it can do with considerable speed), but it can't climb a set of stairs that aren't really, really shallow.

Now let's look at the mountain goat!

It has not two, but three major joints: the ankle, the digitigrade "knee" and a plantigrade knee.

BTW: I know that I'm completely referencing digitigrade joints incorrectly. I'm doing it on purpose. I want you to see the solution that you already have...

...because your drawings appear to show creatures with both a digitigrade joint and a plantigrade joint.

If that's true, you're golden. Your creatures might be a bit uncomfortable climbing stairs, etc., but as @Kilisi says, "mountain goats can go places most humans would balk at" and it's the combination of the two joint types that allows it. As @Kilisi pointed out, your creatures evolved that way, so they likely wouldn't even feel discomfort. They'd do it without thinking.

Now, if you really want those ostrich legs... you're hosed. Pure digitigrade legs would be forced to lean forward and hop stair-to-stair to climb them. And that's the best you could do.

Answer 2

You have the versatility issue backwards.

Humans often switch to digitigrade when doing a wide variety of things including but not limited to going up and down stairs, climbing ladders, and operating the pedals on a car. This is because a flat footed step is only beneficial on flat ground where the rolling action can be used to reduce shock, or if you need to carry a heavy load. But, if you are dealing with any sort of obstacle or limited step space, this rolling action actually interrupts your gait making digitigrade better. Likewise, if you are trying to do any sort of pushing off action, or precision manipulation, you will use your foot in a digitigrade fashion so that you can engage your lower leg muscles for more controlled movement. This is the whole reason most gas/break pedals are only big enough for the balls of your feet and do not come all the way down to the floor.

The only reason a digitigrade humanoid might struggle to function in a plantigrade world would be in a setting where long marches or heavy labor are a normal and expected part of life. So, in a forced march, survival, or labor camp sort of setting, a Salamandrion may have a really hard time keeping up with Humans, but in a sci-fi starship sort of setting, where they just need to be able to function in the same space as the humans to do normal high-tech sorts of jobs, the lack of a plantigrade option will not hinder their ability to function in any meaningful way.

Who Really Needs Special Accommodations?

As established, humans are not obligate plantigrade creatures meaning we may prefer plantigrade locomotion in certain circumstances but have no trouble functioning in digitigrade. So, if your spaceship is designed with humans in mind, then your obligate digitigrades should be fine because their feet are already optimized for the same complex actions that the functional plantigrades are optimized for.

However, what if your setting has actual obligate plantigrades? While humans and Salamandrions may use stairs, ladders, and foot pedals just fine, what if one of your other races can only operate in plantigrade, more like a bear? In general, obligate plantigrades have shorter/wider feet than humans because they are designed to distribute weight, not lift up for extra power. If this is the case, then ladders could pose a major issue because they can not insert their feet between rungs without their shins getting in the way of the rung above it. Foot pedals may also be more difficult to control with shorter feet because you'd be unable to rest your heel on the ground and reach the lever with your toes; so, you'd have to hold your foot up in the air to operate standard human foot pedals.

These minor issues would not be hard to fix though. Ladders would work just fine for obligate plantigrades if each rung has alternating protruding steps. This way each step is guaranteed clearance above it as it climbs regardless of the steepness of the ladder. As for foot pedals, they could just be made adjustable similar like how a steering wheel can be raised and lowered to accommodate drivers of different proportions.

Your tails and wings of course will need additional special accommodations, but that is a different problem all together.

Answer 3

No problem here.

You're unbalanced trying something new. They were born like that and have a lifetimes practice getting around. Birds, kangaroos, jerboas etc,. have no issues getting around. Mountain goats can go places most humans would balk at.

Your pictures have tails to balance with. They should be fine.

Answer 4

They would be fine. With the one on the left, you actually over-corrected with the tail, its too big and would force the centre of balance backward. Either make the creatures lean a bit forward, like a kangaroo or a raptor, or make the tail smaller.

You might also want to make their shoulders narrower, and chest smaller, to move the centre of balance into the pelvis.

And of course consider that your creatures are not going to be standing around all day, imagine them sitting, squatting, sleeping etc.

The tail and the wings pose an obvious problem when using a chair, a couch, or even a bed not designed for them. I think you should consider that your creatures might feel the most comfortable squatting, even for sleep.

The lait and the wings would be a bit awkward in cramped spaces as well, so corridors, rooms, elevators, and doorways would have to be designed to accomodate those.

On another note, how do your creatures use the bathroom? That tail is going to make using a standard toilet a challenge.

Your creatures seem to move around barefoot (which makes sense, since their feet are not compatible with any kind of shoes). Does that mean that they track mud everywhere, and ruin the carpet with their talons?

What about vehicles? do they drive anything? Because standard human cars, coaches, carts, rowboats, cannoes, bicycles etc etc are going to be really awkward for them. Scooters though would work great.

As for your question about stairs: I thing there should be no problem going up; the only difference would be that they would probably "bound" up several stairs at a time, not tiptoe up like a human. Going down however would be awkward, they would be prone to tip forward too much.

The solution here is to make the stairs big and deep, about 2-3 times bigger than what is made for humans, (and more durable, since your creatures are going to gauge the stairs with their talons all the time).

But really, your creatures are mostly just going to skip the stairs entirely in many cases. Their digitgrade feet and plantigrade knees mean they can just leap up and down a story with no issues. Hopefully without landing someone.

Answer 5

The advantage a plantigrade posture has over a digitigrade posture is that the larger surface of contact with the ground gives more stability to a free standing creature. The center of mass has more freedom to move around before the legs have to be repositioned, but that's pretty much all it does. And that only holds up when you compare both postures applied to the same foot shape, some specialized digitigrades such as birds have a toe that points backwards to help with stability, so it's not an universal advantage of all plantigrades vs all digitigrades.

Other than that, the human foot, specifically, may have evolved to allow for our unique gait, which IIRC is very energy-efficient. But other plantigrades don't have the same foot or gait we do. Kangaroos are plantigrades that move mostly on their hind legs and don't walk by putting a foot in front of the other, the same goes for gerbils and other rodents, most of which don't even walk in two legs (like squirrels I believe). The point is that what will define their ease/difficulty using "foreign" spaces and tools is the size and shape of their feet, not how they walk.

Furthermore, human feet allow us to adopt a digitigrade position too, which is beneficial for many things such as exerting force with our feet or step on narrow surfaces. In these situations the digitigrade foot has a clear advantage due to its smaller surface of contact and the extra leverage provided by the ankle joint.

As for walking up and down stairs, I pretty much always walk up and down stairs on the ball of my feet because I find it more comfortable than planting my whole foot on every step. I have never had a problem with this and I don't know how other people do it.

In fact, many humans walk most of the time in an almost digitigrade fashion by using specialized shoes that help their balance (heels) and, yeah, there's consequences because OUR feet aren't made for that kind of gait, but it's perfectly possible for trained people to access places designed for plantigrade feet using a pseudo-digitigrade posture.

So, really, stability and freedom to readjust their posture while freestanding is the only thing you have to compensate for, which you already did since they can intuitively use their tails and/or wings to readjust their center of mass without needing to move their feet. I don't think anything else, other than clothes, would require adjusting. Their contact surface is smaller and more compact than ours. They may hit their knees on the corners of tables more often than the average person but so do I. More seriously: if they get involved in a persecution on foot they may find it hard to do a sharp turn into a narrow corridor due to their posture (and anything they do involving running may face similar problems, but how often do you run as a part of your day to day?), but for normal life outside of action scenes, the biggest problem they will have is that they walk funny and need clothes with wing/tail holes on them.