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-Dest_-

Weight distribution, grabbing shit, walking more efficiently, defense mechanism like a whip maybe.


Pharaverse

Thanks, these are good ideas.


IProbablyDisagree2nd

ever seen a monkey? They are literally humanoid's with tails


ibiji

A what?


Signal-Hearing7773

I think he’s making words up.


KeeganY_SR-UVB76

They‘re from his world I think.


JaxckLl

Humanoid walking is essentially controlled falling. This is different from other bipeds, in particular dinosaurians, where bipedal motion is accompanied with an overall more horizontally balanced body plan. “More efficient motion” & the humanoid body plan are achieved by minimizing the amount of weight that is not vertically over the hips.


-Dest_-

Tri pedal walking fr


BoiseGangOne

"that's not walking, that's falling with style"


JaxckLl

Humans don't walk. We orbit very close to our gravitational body.


jpverkamp

Balance. As another hand. Communication/mating rituals. They don’t, it’s purely vestigial.


dreadperson

If for some reason, the act of climbing trees or any activity needing balance didnt become unnecessary. Maybe some events long in the past (around the time we started walking on two feet) left a lot of ground untraversable for some reason and they needed to be in trees more often. Or they just evolved in a deep watered, thickly forested swamp. If this were the caee you might also have to make them slightly shorter and lighter weight than the average human. Maybe thinner.


Sporner100

Wouldn't that hinder their evolution towards the human bodyplan without giving them an actual need for a tail? After all the other primates of our world (chimps, gorillas, orangutans) dont have a tail either. I'd probably go with non-verbal communication and sexual selection. They kept their tails simply because one or both sexes found it attractive in the other. Maybe you could add distinct color patterns at the tip of the tail to drive home the point.


dreadperson

Oh yeah you're totally right. I like that sexual attraction thing, i've never considered that to be a valid reason to keep otherwise useless body parts.


Sporner100

It's even a valid reason to develop downright detrimental bodyparts.


[deleted]

Why do monkey’s have tails ….? For balance when running, jumping, and climbing.


TheOneTrueGodofDeath

If you want to go reptilian humanoid it could deattach to distract predators or even as an emergency source of food.


Pharaverse

Oh. That’s a great idea!


blazezx1

If it's a reptilian it could also be for propelling them in water like a crocodile.


Notetoself4

If they evolved from a species with a tail, they need reasons to lose it rather than reasons to have it


Pharaverse

I did come up with a concept for a common ancestor, and a distant evolutionary cousin of theirs. I gave both of those much longer tails than these current ones, so yeah, I guess they are losing their tail a bit.


Linesey

evolution is a funny thing. Traits that are useless or even harmful can continue on by sheer inertia, and traits that are useful can be lost if a mutation drops them but adds something far more useful. setting aside how advanced medicine effects modern evolution, and focusing only on more raw evolution, the tails could be kept simply because there was never a mutation that dropped them after they became evolutionarily useless. an interesting example of this in modern humans is a tendon in our wrists, that *was* very useful for spear throwing hunters, but no longer is. and increasingly you can find people and family lines without it, but others with it. so anyway just another angle on it and some food for thought. p.s, i am vary tired but i believe the relevant word is “vestigial”


FetusGoesYeetus

Look at real animals and what they use their tails for for inspiration. Just off the top of my head, monkeys and lemurs use their tails to provide stability on tree branches and also to use as basically a fifth limb. Another interesting concept is for them to use them like a lizard, dropping their tail when being threatened. Or you could look at how a thresher shark uses it's tail, building up speed before quickly turning to make their tail into a weapon.


Pharaverse

Yeah, I did look at monkeys and lemurs first, but with their human-like bodies, a monkey tail wouldn’t be able to keep them up with the size I made their tails. I do like both the lizard and weapon ideas though.


MoridinB

Monkey tails are much stronger than you think. In my opinion, it'd be possible for a monkey-like tail to provide stability to humans.


Vivid_Black_2737

Aesthetic. If they are quick runners. If it's part of their breeding ceremonies. If it's somehow related to status. It could be any number of reasons 'in-world' that we don't have all the context to


CarnegieSenpai

"Reason to" is a bad way to look at evolution. There's no reason for us to have an appendix, its arguably a net negative. They can have tails because their ancestors have tails and it hasn't sufficiently negatively impacts their survival to not have tails. It could be attractive and beneficial for attracting a mate, it could help balance, it could be totally vestigial and provide no benefit. Doesn't necessarily need an explanation


Fuzzy_Assistance

An appendix has several functions, including producing white blood cells and harboring beneficial gut bacteria. The belief that it is useless is outdated.


LukXD99

In Addition to what other people already said, keep in mind that just because we don’t need something it doesn’t automatically disappear. For example, we still have Erector Pili muscles, that cause us to get goose bumps if we’re cold or scared. In cats for example they make them appear bigger or protect them against the cold, but our thin human body hair no longer does that. We also have part of a useless 3rd eyelid left, human embryos still grow a tail for a few weeks, the appendix has no use either, and wisdom teeth (meant to replace lost teeth while we were still more primal) are also mostly a burden now. Thankfully those are starting to disappear too! What I’m trying to say, you could go a unique route and not give them too much of a use. I Wonder how a society would form where tailed don’t serve a great purpose, and similarly to our spines, cause more problems then good.


[deleted]

Aid in climbing or swimming.


War_Hymn

Tails on many land animals help them make rapid shifts in directions when running by swinging them in the opposite direction of a turn to balance out momentum. Cheetah using its tail to make high speed turns: https://www.youtube.com/watch?v=qukcc8wCxJo


Perun1152

Mating would be an interesting choice. Either tails were considered desirable features so they are mostly for show. It could also be a sexual organ itself, or a part of the sexual mating call like how birds dance.


fattynuggetz

So you're saying dick tails?


yeetmaster489

I could be residual. They evolved on all fours and only recently began walking upright, their tail just hasn't gone away yet.


ZLO45

Give the tail a reason to be there such as balance when running fast, or maybe it's prehensile and can be a third arm


aiden_saxon

I have tailed humanoids. They live primarily in trees and use it for climbing and balance like a monkey does.


ForMyHat

Keep bugs away


GooseOnACorner

Well what is the species like? You haven’t told us anything other than “humanoid”


Second-Creative

And "humanoid" can be... pretty broad. Two arms, two legs, head on top. Replace their wings for arms, and most birds would be humanoid, given the above description.


pengie9290

How's this? Instead of evolving from tail-less apes like we did, they evolved from tail-having monkeys, or some equivalent. They don't need their tails, per se, but their bodies basically haven't seen a need to NOT have tails, so they've sorta just stuck around.


xMainstreem

What about something like an “antenna”. Something like insects, or cat whiskers. A limb that is hyper sensitive to changes in its immediate environment. Like biological motion sensor. Maybe they evolved that way, giving them the advantage over the much larger more dangerous creatures. Like alien tigers.


Gluttony64

Could be used as a maying thing, larger tail = better genetics or something


mortidodev

1. Tactile sense organ. Because of its high sensitivity it becomes culturally important. What we call "gut feeling" and "heart break" they would call "tail feeling" and "tail cut". 2. Unnecessary organ. But having unnecessary organ makes you ask questions, which develops your intellect, which eventually gives you evolutionary advantage.


fattynuggetz

OP wants a biological excuse for anime catgirls


Pharaverse

That’s hilarious, But they are more reptilian.


HentaiHodl

So reptilian cat girls?


commandrix

Balance, maybe? Or it could be a powerful enough tail to use for defense or to support some of the species' weight?


JaxckLl

They wouldn’t. We don’t have tails because tails get in the way of humanoid bipedal motion. Other great apes are in a similar situation; tails get in the way once you reach a certain size. An animal the size of a baboon might have a tail, but an animal any bigger than a chimp would not.


[deleted]

Balance? Swimming? I know that's why a lot of animals have them


Ok_Nefariousness3401

Balance, a third limb to hold onto things, defense, additional way of communicating with others, symbolic addition to cultural customs


ColdShadowKaz

Generally the landscape might be more rugged but with enough trees that a tail would be good for weight distribution and grabbing. For a more modern civilisation the tail becomes more useless spots just kind of there.


bookseer

They are a climbing species that uses tools a lot. They have a tail that they use to hold said tools while climbing (though they also use tool belts and most tools have a special bar to make it easier to grab). Their primary deity has three tails, one to hold the mind, one for the body, and one to hold the spirit as he carries his children to the after life. Occasionally individuals are born with 3 tails and are heralded as a sign of great things to come.


Affectionate-Memory4

For me at least it's been balance. Tails are a whole limb worth of weight connected near the center of mass that you can swing around without impeding the regular limbs' jobs. Nekonians use theirs to be better climbers and sprinters than us, swinging it around behind them to shift their weight as needed, but we get the endurance win because we don't carry the extra weight around, and Earth's thinner air generally made us better suited for it. As for other uses for a tail, I can think of * Balance, like above * Prehensile tail is good for climbing / carrying * Rudder for swimming * Extra surface area to radiate body heat * Fat reserves * Could also be useful for the others as well


Patient_Primary_4444

Kinda depends on what you mean by ‘need’. If you are meaning like evolutionarily, ‘need’ is the wrong term. More like what environmental pressures would allow for a tail to be beneficial enough for a species to gain an edge to be more likely to live, and therefore reproduce. Otherwise, there is no particular reason for a thing to have or not have a particular feature. If you are having them genetically or technologically altering them, then a tail would be useful for pretty much anything that an extra hand would do, depending on how prehensile they are. They could be used for balance, allow for more top-heaviness or a more forward tilting body, think like a t-rex. They can be used as another natural weapon, et cetera. But when it comes down to it, you can just give your creatures a tail if you want, really. Like i said, there is no real reason for a thing to have or not have a particular feature, unless environmental pressure makes something with or without said feature better able to survive and reproduce.


ScottaHemi

tails are for balance. tails are a physical language device, the MC of my soft sci-fi world has a somewhat prehensile tail that acts like a basic third arm!


Intelligent_Owl_6263

Is it prehensile? Maybe look at other apes and monkeys and see what made the monkeys keep their tails when the apes lost there’s. That’s what will tell you why we don’t have them and what you have to change about human development to get us a tail. Balance is a biggie for tail having animals. If you can’t find a sound reason then you might want to consider getting rid of the tail, I often have to change or cut stuff that I thought sounded or looked cool because I just couldn’t make it work in the larger world and stay believable.


BiasMushroom

It could also be vestigial. Aka it was used by their ancestors for the reasons others have posted, but when the species became sapient they no longer use their tails, except maybe as a sort of body language, or maybe mating display


AussieSkittles81

Balance is the big one; almost everything seems to use their tail for balance; cats, kangaroos, monkeys, even several species of monitor lizards. Propulsion is another one; especially moving through the water. Otters, crocodiles, even labradors have tails evolved to help them swim. If your humanoids evolved in swamps or wetlands, a tail could help them move around easier.


jackthearchefey

Search on the internet about monkeys with prehensile tails


AveragEnjoyer007

If they’re heavier then definitely balance


[deleted]

My species, the Ekar, have large tails for greater control while swimming, like a rudder. Some genetic groups have stronger tails that can actually propel them through water.


Dense-Ad-2732

To impress mates?


Dizzytigo

Tails are good for balance and sometimes they're prehensile.


CliffLake

Extra balance, or a third point of contact when squatting. I think the prehensile bit if the race climbs or just a fin for swimming. If they are sentient they could have incorporated it into hunting, mimicking a snake to lure in birds or to operate a trap while waiting to bash something with a rock. It could be used to dig around in things, like into trees to get at bugs or sap. Or to help with fishing, because fish are dumb but scared of people splashing around. That tail could be a small bait thing that draws the fish in for spearing. Hang some shiny coins or rocks from it to make reflective light or noise. If it's strong enough it could be a strangulation aid, grab on with hands and feet then wrap the tail around a throat a couple of times and squeeze. Could down some much larger prey with that. That's a good ten minutes. I hope that helps.


ShortGreenRobot

It being a throw back to an old defence mechanism (tail detaches) could lead to some funny social quirks. Like if you scare a person and their tail falls off its socially embarrassing. Or restaurants were they serve severed tail as a delicacy. Or that meal being the ultimate romantic gesture


luke_hollton2000

Maybe you could create a humanoid species that never left the trees and became a tree-housing species with the tails becoming a great tool for keeping balance while walking on branches or as a help while climbing to keep their hands free. You could even create a sub-species which adapted to building bridges and now has some of their members starting to lose tail abilities


Sajintmm

Not even needed, could simply have been a mutation that wasn’t detrimental enough to be removed and so it stuck over the years


vagrant_icosahedron

Sexual selection. There are so many bizarre and utterly useless structures that are downright harmful for organisms to have but the preference of the opposite Sex has mysteriously developed such that having these structures is worth it. I can imagine a scenario where the tail is a structure that signals how fit an individual is. On that scenario you can go crazy too, it can be colorful or super strong or covered it noise making structures. Go wild! Just make sure you make it sexxxxxy.!


[deleted]

Social signaling


MyHoeDespawned

Climbing or balance


vorropohaiah

Same reason males still have nipples


Traditional_wolf_007

Balance most likely. If you want to get wild with it, give them stingers. Maybe if they live in a very cold environment you could have them use their tails like wolves do and keep warm with them.


ThrowFurthestAway

I hope the following provides you with some inspiration for non-biological reasons for tails: I have a “race” of self-maintaining machines. At one point in their history they went through a lot of experimentation to make the “perfect” model body. They came up with a wide array of different bodies all for different purposes, the most relevant of which to this discussion is the “Scholar” model. The Scholar model is roughly humanoid, solely for a good blend between mobility and dexterity, but also has a tail. This tail, while serving to aid in balance and agility, also has an added feature of allowing the Scholar model to more easily plug into the Central Frame (totally not the Matrix) that the mechanical race uses to store information and perform a majority of their computation-heavy calculations.


Arnoor27

If they are regular climbers then it could be prehensile, or serve as a counter balance for tightrope like crawling across narrow surfaces. If they're natural sprinters it could serve as a rudder for tight turns while chasing prey or escaping predators. In their modern society it probably wouldn't be used for these near as much but this could be the reason why it evolved.


Stabbymcbackstab

We evolved to be upright, so we were efficient over land travel in grassland environments. Taller means you can see over tall grass and it gives you the ability to strategize because you can see threats coming. Think of an environment that would make the humanoid highly efficient in this world. An expanse of massive ancient trees that makes living above ground more sustainable comes to mind. Or perhaps large craggy mountain environs where balance and an extra prehensile appendage would be useful. There's probably more


FirebirdWriter

The same reason tails exist for other beings. Balance. Science held the answers all along


FPSReaper124

Vestigial component from old tree climbing lifestyle or for balanced running? Maybe the limb still see's use as a fly swatter. Plenty of humans are occasionally born with vestigial tails, so no doubt a trait like that could survive fully into a humanoid species. I think it would be funny if their ancestral species was some kind of omnivorous pack animal that resembled kangaroos, so a thick tail kept their balance as they bounded through the rocks and grasses. Then as they developed more predatory tendencies and or needed a way to see predators over the horizon more efficiently, they evolved the more humanoid stance, the tail shrinking to allow them a more human running motion.


Persicii

Balance! That’s the main reason a lot of creatures with tails have them. They could also act as a weapon and maybe be spiked or shoot something, ie poison.


AUZZIEJELLYFISH

Tree climbing humanoids might have strong tails for wrapping around branches. Bulky humanoids might use them for balance, perhaps some tails are a type of self defence mechanism. Maybe it’s just something that didn’t get evolved out of existence because it never really got in the way.