Worldbuilding Wednesdays: Selective Pressure

Welcome to Worldbuilding Wednesdays!  Every Wednesday, we spend what is probably far too much time walking through our worldbuilding process.  This week, we add some details to the intelligent species we came up with last week.

What We Have So Far

This time around, we aren't going to gloss over the entire world; we'll just look at our three species.  One of them we already know by heart:  humans.  There will be some adaptations, but not enough to make us think of them as a separate species.  Probably the biggest adaptation to consider is the fact that, while humans will still be pursuit predators, their focus is going to be on ranged attacks.  Running a prey animal to death is more difficult when they need 1/10 the energy they would on Earth to escape you.

Joining humans on this world are two other species.  With respect to the Internet, we're going to give them placeholder names and hope that they don't put us on a list:  furries and scalies.  Furries are arboreal creatures with fur, claws, small gliding flaps, and a posture that allows for running upright along branches in addition to climbing and leaping.  Scalies are amphibious creatures that live among the giant stilt root estuaries, climbing among the roots to keep away from the larger crawling predators.

We haven't gotten much farther than that, but that's what today is for.

Intelligent Design

Before we get started, let's revisit the idea of design philosophy.  It has been a bit since we talked about it in detail, so a quick summary is in order:  When we say "design philosophy," what we mean is that we have a specific approach with some general rules that we use when deciding which direction to take our worldbuilding.  For this series, the design philosophy consists of the following Key Elements:

  Real-World Physics.  Except for changes that we consciously make to the way physics works, the assumption is that things work on our world more or less as they do on Earth.  This means that we don't have to reinvent concepts like aerodynamics, carcinization, or tanning.

  Earth-Like Preference.  We'll make changes to physics (and other sciences) as needed to suit other aspects of our design philosophy, but when in doubt, we're going to be moving toward Earth-like options, rather than away.  For example, while having eight or so legs makes sense for fast-moving creatures on our world, we're going to find reasons that our intelligent creatures more or less resemble the four-limbed species that we'd find on Earth.

  The Bigger the Better.  We are intentionally making decisions that will cause the intelligent species to be relatively small compared to the other animals of the world.  We've mostly done this by making everything else bigger.

  Science-Fantasy.  When we're done, the people we're building will have a civilization that will be relatively modern, and which will blend elements of science and fantasy.

  Inspirational Source.  We're working toward a specific image of a random character driving down the road in a truck, carrying a dragon on a trailer.

The last two might not impact our design of the intelligent species, but it is important to remember:  the goal is to have species that can drive a stick shift.

Peer Pressure

There is one other thing to bear in mind about our three intelligent species, and that is that they're going to be interacting at some point.  When that happens, unless we're interested in the three species becoming engaged in perpetual warfare, we'll want the species to mostly complement each other.  Some competition, and thus friction, is healthy, but otherwise we want each species to think, "Oh, you'll take care of (chore my species hates but yours is built for)?  Neat!  You know, you're alright."

To provide an example of how this can impact our species' designs, let's revisit the length of the day.  A typical day-night cycle on our world is a little more than 40 hours long.  The length of the day doesn't change from season to season, so we can separate our days as follows:

Midnight to Dawn:  10 hours in length

Dawn to Noon:  10 hours in length

Noon to Dusk:  10 hours in length

Dusk to Midnight:  10 hours in length

Now, why did we do that?  Because of two interesting facts that we can take advantage of.  First, humans are built for something approaching a 24-hour cycle, not 40 hours.  While this is because we live on Earth, our design philosophy indicates that we'll want to find an excuse to stick fairly closely to the cycle we're used to.  Which brings us to our second fact:  humans are designed to operate best in hours of twilight, meaning around dawn and dusk.  And on our world, there are a pair of 10-hour bands around dawn and dusk.

Let's say that humans on our world tend to be active during the twilight hours, then rest during the brightest part of the day and the darkest part of the night.  10 hours on, 10 hours off.  One way that the other species can complement, rather than conflict, is by being active when the others aren't.  Amphibious creatures tend to be diurnal anyway, so there's no harm in saying that they like to operate in the 20-hour band between dawn and dusk.  Arboreal creatures, with better eyesight (necessary to not fall hundreds of feet on a slip) and unconcerned with temperature changes thanks to their fur, could easily be nocturnal.  Just like that, we have three species that would work well together on a 40-hour cycle, with humans both bridging the gap between our scalies and furries and operating in a fashion similar to that of Earth.

This particular trick- assuming that the three species are going to blend well, rather than harshly interact- is going to have enough of an impact that we should go ahead and add a new Key Element to our design philosophy.

  Peer Adaptation.  Each of the intelligent species is going to tend to have features that allow them to work well with the others, all else being equal.

The best part about this particular trick is that, since we have humans on this world, we can always start with them when coming up with a particular aspect of each creature.  After all, thanks to our other Key Elements, we already know more or less what humans are going to be like...

They'll be like us.

Round Robin

With our design philosophy locked and loaded, our general descriptions from last week, and a ready knowledge of what humans normally look like, let's walk through a list of details for each species.

  Size.  Humans will be a bit bigger than we're used to.  Lower gravity is going to select for humans that are taller and slightly more massive, although our upper limit is still defined by the fact that we can't get much larger without killing our mothers on the way out.  On the bright side, back problems will be almost unheard of.

  Furries will be smaller than humans.  Arboreal creatures in general tend to be smaller than their landbound variants.  The selective pressure for size will be much less on our world than on Earth, since a given creature can be ten times more massive before they have to worry about breaking a given branch.  Combined with our design philosophy, we can say that furries will be significantly smaller, but not so small that objects built for a human would be too big for them.  Let's say the average furry is half the mass of an average human.  Considering that they'll have a tail (balance and direction control during leaps make that mandatory), and that a typical arboreal tail is about 10% of a creature's body... A furry, on average, would be about 75% of a human's height; that would make them about 1.45 meters tall, or 4'8" in freedom units.  

  Scalies would be a bit larger than humans.  Unlike humans, they need to both swim and climb regularly, so they'll be obliged to carry more muscle than us; we tend to favor lighter, running bodies.  They, too, will have tails, although theirs is more for swimming than climbing.  Again, the upper limit will be constrained by the fact that humans, furries, and scalies will presumably have little trouble living together.  Since furries are at the other end of the size scale, let's say that scalies are no more than 50% taller, which makes them max out at about 7 feet tall on average.  By a fun little coincidence, their average mass would be about 50% larger than a typical human's, and now we have neat little bookends for the size range.

  Appearance.  One notable change about humans will probably be our eyes.  Since we can reasonably attempt to hit creatures ten times further away than we normally would on Earth, our vision is going to become significantly more acute.  While some of that change will be internal, there will be some external cues as well.  To put it briefly, our eyes will get more anime-esque, taking up a visibly larger portion of our face.  The other big change will be to our feet, which will develop some form of adaptation to increase friction.  This can be done in any number of ways, but it amuses us to think that ridged callouses cause our feet to resemble sneakers, even when we're barefoot.

  As demonstrated in our world by cats (and more recently by raccoons), species that interact with humans can and will adapt to be cuter.  It turns out that cuteness is an incredibly valuable survival trait, and it will work even on non-humans.  So it is that we can assume that furries and scalies will have appearances that the average human would consider cute, or at least not off-putting.  The uncanny valley effect, on the other hand, would cause us to kill anything that looks too similar, and so we have our appearance band:  furries and scalies will be humanoid in appearance, with tails and adaptations to their particular environment, and they will be "cute," but distinctly non-human.  Humans will likely have the best eyes, but they'll compete with the nocturnal furries for size, and scalies will at least not have eyes that are considered "beady."

  Speech.  These three species will need to be able to readily speak to each other.  This means one of two things will happen:  The Chewbacca Effect, or similar speaking apparatuses.

  The Chewbacca Effect is seen in Star Wars whenever Chewbacca talks.  He lets out a beastly yodel, and everyone else responds as though they understood exactly what he has said.  We could take this route.  In that case, humans would speak human tongues, furries would speak Furry, and scalies would speak Scalie.  It would just so happen that humans would understand Furry and Scalie, without having to speak it, and the same would go for the other two.  While easy, we'll shy away from this one, since making it work would involve either more questions than we feel like answering or moving away from our design philosophy.

  It's far more straightforward to assume that all three species, having evolved to speak, will have similar mouths, jaws, and tongues.  They could be different enough that some difficulty is involved in learning another species' language, but all three could speak any language that any of the others could.

Conclusion

We'll stop here for this week, since we're approaching our word limit, but you can expect more of the same next week.  As you can see, we're not just building the details for a given species; we're also narrowing down what the details could be.  This saves quite a bit of time- when we're done, we won't just have a complete description of each species, we'll be able to say that they couldn't have looked any other way.