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Although ergonomics is relatively young as a science, humans have been optimizing their environment and their equipment for as long as we’ve been making tools. This has influenced everything from the design of chairs to beds to doors to weapons and tools. And that means that all these things should be just a little different when considering different body proportions and musculature.

This is one of those little things that – if applied consistently – can greatly add to the verisimilitude of a campaign, regardless of whether it is fantasy or sci-fi. If the GM’s investment in time is small enough, the returns on that time investment can be substantial. This article is intended to show you how to minimize that investment while giving the maximum bang for your metaphoric buck. Most of the advice within will deal with the simpler problem of humanoids, to establish the general principles. At the end, I’ll touch on non-humanoids and how their unique anatomies might be reflected in their ergonomics.

The Two fundamental factors

There are two factors that are at the heart of applied ergonomics, so far as a simplified understanding of the topic is concerned. They are proportions and degrees of motion.

Proportions

Proportions are all-important to humanoids. If a race is humanoid, but short or taller than typical humans, that doesn’t mean that their proportions scale to human equivalents; in fact, they shouldn’t do so. The differences can be subtle but profound.

What are normal proportions? How do you find out? The answer lies in the subject of “How to draw comics” – there are multiple books and even a few websites and infographics out there. After a fairly quick Google search, I’ve selected four pages that will tell you what you need to know (I’ve chosen four so that if one goes dark, you should still be able to find the info):

I’ve put these in rough order of usefulness, but each one offers information that the others don’t cover as succinctly, so check them all out.

There’s some interesting supplementary information at the Wikipedia page on the subject but, for a change, Wikipedia doesn’t seem to include the basic information.

Degrees Of Motion

The technical term for this subject is Kinesiology, but it’s a very complicated and technical subject – even trying to read and understand the relevant Wikipedia pages (Kinesiology and Anatomical terms of motion) – which don’t even specify the information we want, just define what it is – is far more work than it is worth for these purposes.

So, instead of technical references, we need something quicker and more practical. Like ourselves, and what our own bodies can do – and, presumably, how our standard tools, utensils and furniture have been optimized to accommodate those capabilities.

The Process

So, I went looking for data and came back with a 3-step procedure. For each item to be “xeno-fitted”:

  • Analyze the relevant human proportions and how they relate to the design & function of the object;
  • Analyze the motions and kinesthetics of the design and function of the object;
  • Apply the variant factors that apply to the xeno-anatomy of the non-human life form to that understanding to identify the ways in which the object will be different for that particular race or species.

Of course, once we’ve done one, it becomes easier to do the next, because there is going to be a certain degree of overlap from one object to the next. After doing a few, it is possible to generalize into some basic principles that describe the majority of tools, furniture, etc, used by that race, relative to their human equivalents.

Elf Dimensions

An Example: Elves

Elves are typically described as either tall, thin, and fair or shorter than humans, with more child-like proportions. Simply to contrast with my chosen second example, I’ve decided (as I usually do) to go with the first choice for this example.

Most GMs, if they think about it all, will assume that you simple scale a human up while keeping the width about the same (Elf 1 in the illustration). Elf 1 is a human at 105% height and 75% width. But that’s not the only way to do it. Elf 2 has a figure, still 75% wide, but with forearms, lower legs, hands, and feet all 10% longer than normal human. The result is only fractionally taller than a human – perhaps an inch or so of average height. Elf 3 is also 75% wide, but has the torso and legs 112% of normal and a little additional slope on the shoulders, and results in a figure that’s a full half-head taller than a human. On this figure, everything but the head is 75% wide. The result is that the figure looks like a small giant next to the other variations. It looks more like a human with giantism than what we want an elf to look like.

So let’s go with Elf 2.

Chairs

Let’s think about chairs. The optimum height for a chair is the height from the floor to the back of the knee, so that the feet are flat to the floor. Assuming our human is about 5’6″ feet in height, and 7.5 heads in proportion, that gives us a scale of 1 head = 8.8″, big hair notwithstanding. Our elf’s knees are about 1/3 of a head higher than those of a human, or almost 3 inches. If an elf sits in a human chair, the back of his knees will be three inches off the chair base – which is about as much as most people can actually lift their knees while in an upright sitting position. Try it, and you’ll find it acutely uncomfortable. Elves would naturally splay their legs out in front of them while sitting in such a chair, a posture that humans regard as extremely casual. The legs would also tend to open naturally, which generally means – in terms of human kinesthetics – that they find the person they are looking at to be attractive, and which tends to make the person so sitting look more attractive and open to those perceiving them. It’s also an indicator (in human terms) of a certain moral looseness, shall we say.

At the very least, Elves would appear casual and friendly in a human setting.

Elven chairs, on the other hand, would be at roughly the height of slightly-short kitchen stools, with tall backs. A human sitting in one would find the back of his foot off the ground by about three inches, his legs dangling before him. They would have to consciously lift themselves into place to sit on one. Just while sitting next to a chair, just hold your hand flat about three inches above it to get some idea of the difference.

Tables

The ideal height for a table is roughly one head taller than a chair base, perhaps a little more or a little less – call it “Give or take an inch”. That’s all about the length of the torso while sitting, less the length of the upper arms, so that the hands are at 90 degrees to the body. This is not the perfect height for exerting force, but it is the perfect height for detailed work like writing, eating, and so on.

Let’s now apply our determinations of Elf proportions. Elf 2 has a normal human torso, and normal human forearms, so the height above the base of a chair will be exactly the same as it is for human furniture – one head. But Elven chairs should have legs three inches taller than the human equivalent, and that means that their ideal table and desk height will also be three inches taller.

Go ahead – pick the nearest table and hold your palm flat, about three inches above it. Lift your elbows so that they are also flat relative to the palms of your hands. That will give you a notion of what it would be like for a human to use an elven table – doable, but not very comfortable. Now hold your hand flat about three inches below the surface of the table. That’s what a human table would be like for an elf. Again, it’s manageable – but far from comfortable.

Now do it sitting down and lifting your feet about three inches off the floor. I don’t know about you, but that puts my hands below the height of my knees by some margin. This just gets better and better, an elf might (sarcastically) think. Again, the elf has no choice but to slouch and splay his legs out before him when using human furniture. On a typical modern dining table, that probably means that he’s playing footsies with his neighbor on the far side of the table, and fairly aggressively doing so. Add the renowned good looks of the Elf and he’s probably sending invitations that are likely to be well-received without even realizing it. Humans who expect to receive elven guests would do well to have a table that’s an extra foot or two wide!

Beds

The ideal bed is one that is at the same height as a chair. By now, you know what to do next, but I’ll spell it out anyway – go to your bed and hold your hand about three inches above it! Think about what it would be like getting into a bed that tall. I’ve actually slept in one that almost matches (it was about 2 inches taller than normal) – it’s a little awkward, and you feel a lot higher off the ground than usual, not just the small amount you might expect!

Now hold your hand three inches below the top of the bed. Elves would practically have to fall into a human bed, or lower themselves very gingerly. More likely, they would kneel on the bed, then maneuver themselves into position before lowering themselves down.

Workbenches

Workbenches are all about exerting force while standing. The optimum height is roughly somewhere between the height of the hips, and the height of the shoulders less the height of the arms when they are held at a 45-degree angle downwards.

If you stand up with one arm to your side and use the other to note the height of your hips on that arm, you will find it almost exactly midway along your forearm. A forearm is also roughly two hands in length, you will note. The arms themselves – measured from the shoulders – are about three heads in length, about the same distance as neck-to-groin.

Ideal workbench height is about groin plus half-a-head, give or take an inch or two. Locating the groins on our illustration above for both human and Elf 2, and adding about half-a-head, we can see that there isn’t going to be very much difference in height between the two.

Chisel

Workbench tools

However, a greater proportion of the arms length is used for forearm, by a considerable amount. If you hold your wrist up to your shoulder, bending at the elbow, you’ll find that the wrist is at roughly the same height as the armpit. Our workbench tools – chisels, screwdrivers, etc (hammers excepted) – are designed so that when we grip them, the working end of the tool is about as far from the wrist as the tip of our fingers would be, or a little more. (Hold a screwdriver in one hand and the other hand palm flat against it so that the wrists line up, and you’ll see what I mean). The forearms of our elf are about half-a-head longer than those of a human – call it about 4 inches. So, to see what it’s like for an elf to have such long forearms, try holding the tool – or a pen or pencil – four inches further back up the handle than you normally would. Now pretend to use the tool while holding it in that position, disregarding any grip issues. Maneuver it around a bit.

You’ll find that movements are exaggerated in range of motion quite substantially. It’s actually much harder to be delicate, but much easier to make broad sweeping motions. Now, still holding your tool in the “elven position”, with elbow bent, bring the tip of the tool to a position directly in front of you, as you might for delicate work. You’ll find that your elbow is further back than you expected, and that the tip of the tool tends to be closer to your eyes. You naturally find yourself working closer up.

This is both a good and a bad thing. It means that such delicate work is naturally easier to do (grip problems being ignored) but that any slip is more likely to result in a facial injury.

To optimize tool design for use by an elf, the gap between handle and point would be about four inches shorter than it is in human tools. This also aids greatly in delicacy of work, but makes it harder to exert physical force to any great degree. (At this point you can probably see why I chose the body proportions that I did – they naturally produce so many Elven characteristics).

These longer forearms would also give them greater natural leverage, especially if their longer fingers gave them a tighter grip. It is likely that their handles would be fatter than the human equivalents, which would also aid in precision craftsmanship.

The leverage effect will also be all the more important when I consider the next item on my list.

Hammers

If you have a hammer handy, pick it up and then slide your grip from it’s natural point back about four inches (holding the head in your other hand so that you don’t drop it). In most cases, your hand will have slid clear off the handle by an inch or so. To get a feel for how a hammer will behave in an elf’s hands, we need a substitute. The best one that I can find is one of those half-length folding umbrellas. Gripping one near the end, the same way that you would a hammer, try imitating a hammer’s action – don’t use any force, we don’t want to break it. The weight, at a greater distance from the hand, makes the hammer clumsy and unwieldy. You can deliver much greater force, because the hammer head (once moving) will be at a greater distance from the elbow, and so (for a given angle of movement) will be moving faster and have more momentum. In fact, since the circumference of a circle is 2 x pi x radius, the increase in hammer force will be roughly 6.25 times the ratio of the radii – in other words, the ratio of lengths of the forearms. Since the forearms are defined as 110% normal length, that gives us a hammer force of almost 7 times what a human produces, for the same amount of effort – and, probably, 1/7th the control.

To compensate, we need the hammers to be smaller and lighter – one 7th the weight, to be exact. A standard claw hammer weighs 16 ounces, according to Wiki Answers. So we’re talking about a 2.3-ounce hammer, or about 65 grams – about the same as a bar of soap, a large egg, or a slightly small metal serving spoon (most of those are 100-120g in weight).

No hammer so light is going to stand up to the punishment of actual use. Some of the weight can be saved (and some precision restored) by making the handle shorter – say, to about 4 inches in length – and some can be saved by making the head about half it’s usual size (by volume). The rest simply has to be coped with by hitting more gently with it – “tapping with great force”. “Many taps make light work”?

Putting things together with nails is, nevertheless, never going to be a popular elven technique.

Hoes, Rakes, Brooms, and other long implements

Most poled implements stand somewhere between chest high and slightly taller than head high. Chest high is the ideal for control, because it places the gripping position at about the same height as the human center of gravity, while above head height keeps the head of the implement above the head of the user when the item is being carried – an important feature for safety. The sharper and more dangerous the head of the tool, the more likely it is to be elevated well above head-height – even to the point of attaching an intermediate handle position so that the implement can be controlled with one hand and swung with force with the other, as is the case with the standard scythe, favorite of figures of death.

Our elf stands about human height, so the maximum won’t be that much different. When you examine the figures closely, though, you will notice that the center of the chest is perhaps an inch or so higher, and therefore so will be the center of gravity. That means that the minimum length is going to be longer by that inch or so. The power when using such tools comes from the shoulders (try swinging a broom around and you’ll see what I mean) while the control comes from the arms, especially the forearms. The overall mass of the user also makes a difference, and here our elf will lose out to a human.

A human using an elven implement, especially one designed for two-handed use, would find that the balance was all wrong. The effect is the same as having too heavy a head on the implement. Elves would struggle to match human effectiveness in terms of raw power – but would have much greater control. Because of the longer forearms, any mid-length grip would be closer to the head of the implement – probably a couple of inches too far for the human to reach. That would necessitate shifting the upper grip position closer to the head, making the implement less effective and more unbalanced. Human tools tend not to have any grips, or (where they do) to have those grips be smaller in diameter than the surrounding material – you create your implement and then carve the grip out of the material. The grips are indented. Elves, with their longer fingers, actually need the grips to be rounder and wider than those of a human, and to save weight, the rest of the shafts would be smaller – first, because they don’t deliver as much force, and so don’t need the implement to be as robust, and second, because they don’t deliver as much effect, and so will have to wield the implement more times to achieve the same level of work, and so want it to be lighter than the human equivalent. The general principle once again is: more strokes, more precisely and delicately applied.

Curiously, when you think about it for a while, you will find that the best way of thinking about an elf using a human implement, you will find that for completely different reasons, they would have very similar complaints. The balance point would be all wrong – the mid-position hand would be too far away from the head. The result is once again analogous to having an over-sized head on the tool!

Steps

Is there a set of stairs anywhere near you? If you put one foot on an upward step, you will find that humans have steps that are most of the length of a human foot deep, and that your thigh is at a little less than a 45-degree angle – anything more than that we find too steep, anything less than about 30 degrees is strangely shallow. Angle and thigh length therefore dictate the normal dimensions of human staircase steps.

Now, let’s think about our elf. The thighs are about the same length, but to set foot on the next step, their longer calves mean that they have to raise their thighs to a higher angle. The difference is about half a head, or four inches. Get some books and sit them on the step (cover them with something if you don’t want to mark them) until the step is about four inches taller than it was. You’ll probably find that the top is now only about an inch below the lip of next step up! Put your foot flat on the heightened step and notice how uncomfortably steep it now seems. An elf going up a human staircase of normal dimensions would find that it was very steep and would also be far more likely to trip.

Elven steps would be only about an inch, perhaps two, in height – less than half those of the human standard. Because they would want to keep the steps practical in total length, that would require the depth to be smaller – again, about half. This is quite manageable, most stepladders have steps of that depth; so humans would take elven steps two at a time and with only the balls of their feet supported. That’s fine unless you are carrying a heavy weight – when trying to proceed on tippy-toes is most uncomfortable. The unbalancing effect of the weight doesn’t seem like it would be the equivalent of carrying twice as much weight – I suspect that it would be more like an extra 40% weight, but have no math to prove it. Elves would have lots of small steps that they could scamper up; if a human tried to match an elf’s pace up one of their staircases, they would probably trip.

ovals

Clothing

Human clothing of the right length would have sleeves and trouser legs that were too short for an elf. They would also be very loose on the body – wide sleeves, etc – as though they were several sizes too big.

Elven clothing, if bought to length, would not fit on any but the skinniest human. Instead, to get clothes that fit, you would need to get clothes that were considerably larger.

Our elf’s horizontal dimensions are 75% of those of a human. What does that really mean? The obscure image to the right should help to explain it.

Viewed from above, the human body is more or less oval in shape, especially once the shoulders are allowed for. That’s the blue oval and the outer pair of yellow ovals for the shoulders. There’s some error, but it’s close enough. If our elves were 75% narrower across the shoulders but the same width front to back, you get the red oval. If they are also reduced 75% front-to-back, you get the green oval and the two inner yellow shoulders. I suspect that the reality would be somewhere in between – say, the average of the red and green ovals. The ratio of the areas should give us the ratio of clothing size.

So:

  • blue oval = pi x A x B in area.
  • Red oval area = pi x 0.75 x A in area.
  • Green oval area = pi x 0.75 x a x 0.75 x b = 0.5625 x pi x a x b.
  • Average of Red and Green ovals = 0.5 x (pi x 0.75 x a x b) + (0.5625 x pi x a x b)
    = 0.5 x (pi x a x b x (0.5625+0.75))
    = 0.5 x (pi x a x b x 1.3125)
    = 0.65625 x pi x a x b.
  • ratio of blue oval to average of red & green ovals = 1/0.65625 = approx 1.5. Which should have been more-or-less obvious from the start.

So a human who normally bought a size 12 shirt would have to buy a size 18 Elven Shirt to get it to fit his chest. That means that the arm length would also be that of a size 18 shirt – roughly 1/2″ longer per size increase, or about 4″ too long. The same goes for the pants, except it’s closer to 3/4″ per size increase, or about 6″ too long.

Either you have the sleeves cut down, or you have them made with tight collars on the sleeves – not an imposition because the elven wrist is the same size as the human – and have very loose, billowy sleeves. The same goes for pants. A very definite style, and the sort of thing that high society types would go all ga-ga for.

And that same measurement discrepancy – 4 inches and 6 inches – is how short the sleeves and legs of human clothing would be if bought to fit the elvish chest. The same ratio applies both ways – Elves would need to buy 1.5 times larger than that indicated by their shoulder measurements to get human sleeves of the right length, meaning that the chest and waist sizes would be that much too large. Next time you’re near a clothing shop, duck in and take look at something eight sizes too large for you!

Wrapping up

I wanted to now go into another example – I was going to use Dwarves, making the assumption that they were shorter, heavier, broader, and had less flexibility in bending at the waist, and in particular focusing on how these changes would influence their architecture, their mining tools, and the mineshafts that they create, so as to demonstrate the impact of the second factor (degrees of motion) on their furniture, but I’m completely out of time.

If there’s enough demand, I’ll do Dwarves some other time – but even without that, these examples show how quick and easy it can be. None of them took more than 3 minutes – and, if I exclude the clothing, that drops to under one minute – to think about and decipher.

It took a lot longer to explain what I was doing and write it up. In total, all of the above amounts to rather less than ten minutes work (less description and illustration).

In return for that time investment, Elves have become far more concrete in their visualization. I can state general principles about elvish architecture, about elvish clothing, about elvish tools, about why they are such good craftsmen – and why even a human familiar with the principles would take time to master Elvish tools, and never be as good with them as their creators. I can describe Elves in a human setting – and justify both their apparent attitudes and the way the general public perceive them, purely in terms of their anatomical structure. I can also describe what humans would experience in an elvish workshop, or an Elvish council setting. The furniture and tools they use have become unique and characteristically theirs.

The anatomy fits the cultural profile from multiple sources, and the tools fit the anatomy, and the tools explain and justify that cultural profile. So take a few minutes – and these simple principles – and apply a little ergonomics to your races. Start with the PC races, and expand out from there as necessary.

Okay, I messed up – I misremembered the formula for the circumferance of a circle. Don’t bother looking for the error, it’s now been corrected – and it only impacted one section of the analysis, anyway.

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