This is a question for those of you with more science knowledge than I have.

What environmental factors would lead to a human/humanoid type race having nicitating eyelids and vertical pupils? (in other words "cats' eyes")

One of the players in my current bunch has her character as mostly human except for those two features. She and I are trying to come up with a nearby star with a starsystem where that would make sense and her character would have grown up there. (before her character entered Starfleet Academy)

Any ideas or thoughts?


- Ed C.

Look at species on Earth that have them and extrapolate. I'd say maybe an aquatic or amphibious species (I designed one for GURPS: Humaniti, althought they were engineered rather than evolved) or, alternately, one that spends a lot of time in arid/desert conditions.

Probably not amphibous.

 She and I agreed when she roughed pout the character's background that her people look 90% human - just with minor differences like that. Think she even said that her people can inter-marry with Terran humans and have kids - with a little medical help.

Think she just liked the idea of having vertical pupils like a cat.

- Ed C.

The shape of the cats pupils along with several other features allow cats to have superior night vision. If I remember correctly they need only about 1/6th the amount of light to see compared to a human. So if a character/alien has this type of feature. It would make sense if they were noturnal or come from some kind of low light environment.

The rotation of the planet could cause the most inhabitable local to be primarily nocturnal.  Perhaps around a tilted pole.  Also if the place was subjected to lens flares that would have some impact on the eyes as well.

Alternatively the surface is generally inhospitable so they primarily live underground, this would account for both nocturnal vision and a generally dusty environment to create a special need for nictating eyelids.

Quote from: Ronin;357954The shape of the cats pupils along with several other features allow cats to have superior night vision. If I remember correctly they need only about 1/6th the amount of light to see compared to a human. So if a character/alien has this type of feature. It would make sense if they were noturnal or come from some kind of low light environment.

It's a combination of the slit pupil and chatoyance. Chatoyance is a reflective layer inside the cat's eyes which magnifies the intensity of dim light. This wasn't mentioned, so it may or may not be present. Thing is, any trait can be introduced with genetic engineering. Evolution takes a very long time. The light enhancement thing may be merely cosmetic or it may be an engineered response to dim light conditions, such as being from a world around a red dwarf, or a world outside the habitable zone around a yellow or orange sun.

-clash

Agree with the above in that such a change would most likely be deliberate genetic engineering. Human social activities such as interstellar colonisation happen way too fast for evolution to be a factor.

Other factors which might cause the development of such eyes include arboreal hunting/tangle hunting. (Hunting through areas which change light conditions fairly rapidly even at night.)

Quote from: Premier;357965Agree with the above in that such a change would most likely be deliberate genetic engineering. Human social activities such as interstellar colonisation happen way too fast for evolution to be a factor.

Except this is Star Trek. Different races can cross-breed to come up with different characteristics.

Yup, anything goes in Star Trek. Really, I don't even see a true need to go into ANY detail about homeworlds and such unless your PCs end up going there. Just make her another "forehead of the week" species and move on.

Quote from: Werekoala;357982Yup, anything goes in Star Trek. Really, I don't even see a true need to go into ANY detail about homeworlds and such unless your PCs end up going there. Just make her another "forehead of the week" species and move on.

StarTrek explains with technobabble. Think of this as fairly realistic technobabble. You don't need realistic in Trek, but if it doesn't interfere with the plot, there's no reason not to either.

-clash

Just say that they were an offshoot from when Kahn and his buddies were messing with genes left and right..  or just say that it happens and makes sure the player is ok with never going home so you don't have to come up with further reason.

Full props to you and the players for trying to come up with a reason however. (techno babble or not, gndn (goes nowhere does nothing) conduits and all)

I'm thinking of going with Altair.

Its fairly close to the Terran/Earth star system and it got mentioned on the various shows a few times - but we never directly met someone from Altair.
(Either Altair IV or Altair VI)

Most versions of TREK the ship was on the way there or it was referred to in connection with something else.

For example: McCoy ordered " Altair Water" in the bar in ST III:The Search For Spock. Stuff like that.


- Ed C.

I thought in trekology the homo-sapiens-ness of all alien cultures was down to some ancient pan-universal genetic seeding by one of those master races that have progressed beyond physical forms blah blah.
Ijn any case the shape of a cat's iris really has nothing to do with night vision at all. That is ther reflective coating at the back of the iris. The shape of the iris is more related to the field of focus. Cats focus their vision in a slit not a point. Must give 'em some advantage hunting small prey... Might also give them better depth perception as well. Most nocturnal animals just have big eyes and even big cats don't have slits. Owls and lemurs being great examples of creaures with night sight much better than cats. Maybe its a fashion thing, I can see cats evolving cool eyes just out of vanity.
Any you need to be careful when giving planets stuff like dark-sides to explain noctural hunting cos the knockon effects like no photosynthesis, vitamin D etc get harder to explain than the thing you started with in the first place.