How Intelligent Life Evolves (And Why It Probably Looks Human) | Worldbuilding 

Sir, did you just evolve scientifically viable Mindflayers?? (I'm both impressed and Concerned. Those things scare me.)

Interesting thing about the relationship between sapience and language and learning; it has been scientifically proven that Cetaceons (whales and dolphins) have language. They don't just make sounds like other animals, but aftual language and even different dialects. We have yet to figure out how to translate cetacean to any human language, but we do know they have their own language. Additionally, we also know that octopi can not only learn how to perform tasks; they can also teach those skills to other octopi. For example, you can teach a dog to sit and roll over, but that dog can not then teach those skills to other dogs. However, if an octopus has learned how to unscrew a cap on a jar to get the food inside; that octopus can subsequently teach that skill to another octopus that hasn't learned it yet. Additionally, scientists have observed octopi building at least 2 cities (on the ocean floor) with rules of behavior they enforce with banishment.

You could actually have Elves and Dwarves also evolve from the Nota, similar to how Neanderthal, Denisovens, and Florensians all evolved from Sahelenthropus

Personally, I disagree with the Silarin becoming *that* much of a hominoid "lizard-man" species. Cephalization ≠ Hominization

14:35 One little nitpick: Having a large, thick tail to counterbalance the front of the body works just as well as an erect back. If it worked for very large hunters like T. rex, I don't see why a convergence on a human-like body plan would be necessary. In response to a similar, earlier concept for intelligent humanoid dinosaurs, an artist named C. M. Kosemen came up with an intelligent species that conserves a dinosaur-like bodyplan called Avisapiens saurotheos. Since RU-vid doesn't like links very much, just searching up "C. M. Kosemen Dinosauroids" and clicking the first page suffices.

There are some adjustments I'd make (because I'm a biologist) to these alien species - particularly the one based on an octopus. Octopuses actually have very strong arms, which are very adept at grabbing, holding and manipulating objects. And just try to remove an octopus from something it's suckered on to - it's well-nigh impossible. They can open jars, and are well known for removing crabs from crab traps, as well as being able to reach into all kinds of crevices, grab something, then pull it - hiding inside coral formations offers little protection from an octopus! Also, if the alien octopus was similar to an Earth one it would have a (rather vicious) beak and neither a larynx nor a syrinx (which is what birds use). So it wouldn't be able to speak unless that particular trait was changed. Just some thoughts from a biologist's perspective. I still love your work though!

Dinosaur-like bipeds already have an excellent adaptation to expend far less energy when standing: Their tail. The only benefit of an upright stance from a biomechanical standpoint is that it makes it easier to balance a top heavy body on hind limbs located at one end of said body. But a heavy tail already fulfills that function. Dinosaur (and Callidus) hind limbs are much closer to the creature's center, removing the reason to evolve an upright stance. Such a raptorial stance is even more efficient than our upright stance because the tail and torso act as a balance rod, requiring less energy to keep balanced. Some birds even sleep standing. I haven't seen many humans able to pull that off. But it's not just more efficent when standing still, but especially in motion. Meaning, a raptorial stance allows for much greater speeds and stability at those speeds than our upright stance. Even modern birds without long tails still retain the horizontal body orientation with only one noteable exception: Penguins. Their aquatic lifestlye benefited their legs to be closer to the rear end of their bodies, resulting in an upright stance to be beneficial on land. The stance also doesn't impact sapience at all. The front limbs are just as free as ours, and a long neck solves any height advantage a humanoid body might have. So, no, their posture becoming humanoid doesn't make much sense from an evolutionary standpoint. The only reason for it would be an anthropocentric preference. Which is a completely valid reason.

Wtf, I've been binging all these videos and only just realized how many subscribers and likes you get. This channel feels more like a 500k type of world building channel, and definitely deserves more than what it has.

This is definitely a fun part of the process. Interested in seeing how these creatures develop over time.

One thing I do want to specify is that birds do something weird, but definitely still function within this system. They are tetrapods, but two of their limbs are utilized for flight. So they only have two limbs (their legs) with functional digits. For birds that are specialized for perching on branches (as opposed to ones which run, like ostriches), these digits can squeeze and grasp. So their manipulating limbs are *also* their locomotive (when on the ground) limbs, and are solely manipulative limbs when flying. Alongside this, they adapted their mouths to be really good manipulative tools, as they have really complex neck muscles which allow for great dexterity. In combination with their feet, this trifecta of manipulation has interesting positives and drawbacks. Looking at corvids, they use their feet and beaks to complexly break down food items. For manipulating material, they use their feet and bodyweight as anchors while they adjust items with their beaks. They can even pull a hanging object up with their beak, gradually trapping the slackened string under their feet to make sure it doesn't fall back down. Ravens often pass items that they are carrying between their feet and their beaks as they are flying around... we don't know why, but because they are such complex/technical fliers, my guess is that they're modifying their weight distribution for different maneuvers. And corvids are clumsy (as they scavengers that are more generalized for many tasks) when compared to parrots! Parrots can move their top and bottom jaws indepentantly from one another, which allows insane dexterity! Their feet are also more hand like, as they spend way less time on the ground than crows, so they are really good at item manipulation. Basically, please be creative with how your organism is shaped! Keep in mind the fun complexities and challenges that exist based on design benefits and limitations! The rules laid out in the video are great, so follow them most definitely! But also don't be afraid to put a fun twist on the rules. Off the top of my head, I can imagine a highly intelligent species of bird that has a specialized break, and has the ability to stand on one leg for long periods of time, such that it can use one foot and its beak in tandem. That, or one that can comfortably sit and make both feet available for use :)

I think the Naquil are less likely to become parasites. Their high brain function and large number of manipulators makes them well suited aquatic organisms and could build an entire subaquatic culture that is focused on secrecy/stealth for survival. A dark forest analogy on a less grand scale.

I could easily see Na'qwuil going on to selectively breed certain creatures to optimally function as their hosts, almost like having livestock species to act as their perfect bodies depending on their specialization in society. Maybe they would even try to develop hosts that can survive without a brain so they can switch between host species more freely. I've also got to wonder what role technology would have in all this once they invent robotics capable of reading neuron signals. All very interesting stuff. I can't wait to see how you develop it!

Re: it probably looks human? I think this is largely going to be true if the initial seed is a long-limbed quadrupedal terrestrial or arborial mammal that adapts to use its forelimbs as manipulators, especially one which lacks a heavy balancing tail. However, it's far less clear what happens if the initial seed is something very different. If for example the body segments or limb count are different, or if it has a reptilian side-to side spine, only some things will converge, and some definitely won't. If monitor lizards develop sentience, it is rather unlikely they would look like us. Maybe more like us than they do now, but not like us. Corvids, parrots, and otters have developed pretty extensive tool-using intelligence, but do not take on a human bodyplan. Nor is there any indication that they would do so if they began to make greater use of more complex tools along the lines of great apes. A corvid which uses hammer and anvil or ties knots need not lose its wings or tail and convert to having hands. Instead, it would likely evolve a more stable leg setup and a more effective manipulatory beak. Perhaps even a manipulatory tongue. But would overall remain vaguely Corvid-shaped and would near certainly make whatever compromises needed to retain flight, even if that limits intelligence or tool use. An otter which makes increased use of tools would likely remain mostly aquatic and retain its relatively short limbs and long twisty spine. It might even make its spine longer and twistier to more easily access and manipulate objects. It seems decidedly unlikely though that it would evolve into a terrestrial upright longlegged biped, even if it developed things like fire.

Re: octopodes lacking strength? I don't think this is a terribly big problem. Tentacles are as, if not more, muscular then limbs. Squids are capable of using their tentacles to form wings even at a perfect cantilever and despite having an atrociously high wing loading. They even migrate more efficiently using repeated ballistic or aerodynamic flights than swimming. The bigger problem is gonna be lack of rigidity or inherent stability rather than lack of strength. A cephalopod probably can't take an upright body posture. Even one strong enough to fly.

For my own worldbuilding, I have chosen to stick to merpeople, humans, elves, gobelins and dwarves. They are all competing for ressources, but humans have the edge. However, certain places have reached a certain equilibrium. In moutains, usually the humans would save for themselves the verdant lower parts for agriculture of plants such as wheat, buckwheat, pea and/or rice, raising cattles such as pigs, sheeps, goats or bovines. Dwarves require more calories than humans, however, they are much more capable of surviving altitudes due to having a larger ribcage allowing for more powerful diaphragm and lungs, which is great to live in area with less oxygen. They would be perfect to live in the boreal forests closer to the mountain top living off of hoarding animals such as sheep and goats, use crevices to cultivate mushrooms in large quantities cultivate certain coniferous species for sap, vitamin-C rich needles, oily seeds and wood. Another factor is that dwarfs would have rather small kidneys for a large bladder, able to rapidely eliminate excess fresh water from their system. Their physiology is also well-adapted for the cold, and thus they would share the alpine tundra with elves. Elves get cold easily and are quite frail, however, their hollow bones, flight and the fact they are fungivorous (with resistance to ergotamine) make their survival in the alpine tundra far easier. Similar domains such as tundra would also share a similarity. Lands of the undead and evil spirits would also push for cohabitations of elves, humans and dwarves on the same plot of land. Humans found the undead political lines, however, they are mostly a single necromancer controlling an army of undead and to perform their dark rituals, kill most unfortuante fellow human beings who happened to get on their wrong sides. Dwarves and elves have both evolved to cohabitate and cope with evil spirit troubles and the various unpredictable dangers they pose. However, the decomposition fluid encourage the formation of fertile soil, thus leading the two sapient humanoid species to willingly cohabitate with the humans who created those spaces.

The bear men make sense, but the already bipedal lizards had long balancing tails and therefore no reason to go through the semi-dysfunctional process of becoming vertically oriented to the point of developing chronic back pain

I would argue an upright posture would force silarins to sacrifice their speed, which would be too costly for plains hunting obligate carnivores, and they'd gain all the spinal and joint problems that come from humanoid bipedalism. If anything becoming more ostrich-like would be the most likely direction, albeit with bigger heads/thicker necks and arms replacing wings. I'd also argue the competition with the silarins would keep the nota off out of the savannahs and from ever developing the human biped physiology, instead retaining more climbing related adaptations. They'd probably end up as weird hairless almost human monkey people, like shaved chimps but with people faces. I do think the na'qwuil turning to parasitism to overcome the whole no bones issue is a really cool idea though.

Hey! I'm a Predatory, Land Dwelling, Bilaterian too! What a coincidence ;) Great job! I just discovered this video, I'm looking forward to starting from the beginning!

Weird nitpick, but didn't we lose our fur because we evolved to be endurance hunters, not cause of fire? we sweat, which is why we lost our fur, as it impeded our cooling system. Am I wrong?

Re: visual communication reduces capacity for language? I somewhat disagree. Humans and cephalopods make extensive use of direct and indirect visual communication. It is not that hard to imagine sign language, dancing, or bioluminescence used for a significant part of culture transmission.

I like your take on cephalopods. I reached back to their shell-dwelling ancestors to make them viable on land. Like a crab, they encase their limbs in shells to make them rigid. As consciousness developed, they started manipulating how their shells grew, for function and for art.

You know, when I was creating sapient species for my setting a few years ago, I went through the exact same thought process and got very simmilar results. I put creatures simmilar to your Silarin (I called mine Skyrann), but I did not go as far as making their posture completely human-like, as well as I did not make their tails vestigial, which resulted in more angled posture, especially when running. I also gave them sparse feathers, but also made them grow thick coats of them during the mating season, when males are blue-violet with peacock-like feathers both on the tail ends and on heads, while the females are just brownish. I also changed their skin colour range to brown - dark red, as they were evolving under a stable red dwarf star, so vegetation had different colours and it simply helped them hide.

I disagree that sapient species would have to be Predatory, many highly intelligent species are omnivores or even herbivores. Take elephants for example, they have complex social structures and rituals, use tools, and solve problems set to them by scientists. Even crows have social rituals (have been observed mourning their dead and attacking anything trying to get to the corpse) and are extremely good at problem-solving. There is reasonable evidence that would suggest early hominids might not have even been predators either, since 2 of our closest relatives (bonobos and gorillas) do any hunting (though chimpanzees do hunt). A theory in this regard is we were scavengers at first, stealing meat from kills made by other animals. I would agree we became predators once we had the intelligence to outsmart prey, but that only happened after we mastered fire (I believe the archeological record shows our brains getting bigger at around the same time that we find cooked food in our rubbish piles.) I would also argue that being a predator would in fact make sapience less likely for 3 main reasons: 1. (majority of) predators use some form of physical prowess, rather than intelligence, to take down prey, thus nutrient resources are better spent building muscle rather than brains; 2. predators would struggle to get enough nutrition to support brain development (again human brains growth is correlated with our ability to increase nutrient availability by cooking food); 3. avoiding predation requires more brain power than hunting as to avoid being prey you need keen spacial awareness, constant vigilance, and creative problem solving to use your surrounding to avoid the predator.

I've never liked that "We relate to /care more about very human-ish characters!" Maybe it's just 'cause I'm autistic but I care way more about, say, a moderately anthropomorphized jumping spider than a human or elf character.

Humans are my neck pain and agony as a world builder. They are everywhere, even when I WISH to not have them completely or to remove them completely from the worlds I have created. In the end, having to force myself to include humans in my worlds has left nothing but frustrations and dissatisfactions. In every RPG that I have had the misfortune to GM, there is never a lack of someone who necessarily wants to have a human character in one of my worlds...Only to end up playing a clone of an existing character. I don't know... I just don't want to see humans in my fictional worlds... I have enough of seeing them daily in the real world and looking in the mirror.

I disagree about a therapod-like body plan converging towards upright posture. Those tails are vital to the way they move. While there are counterexamples like some of the therizinosaurs, as well as penguins, none of them are fast running endurance-oriented creatures of the open planes. Meanwhile, the animals that move in a similar way to what is suggested seem to conserve or even reinvent the theropod bodyplan. Ratites and terror birds keep a horizontal spine and just have long upright necks. Terrorbirds are notable here because they have an enormous skull and heavy axe-like beak which suggests that a large braincase would be fine from a structural standpoint on a neck like that. I also wish if using their hands as manipulators is likely. This would be highly unnatural for a theropod. It is far more likely their their mouth or feet or more likely, both would be used. All examples of tool-using theropods fit this model, and even before birds, the front limbs tended to be inflexible and wing-like. Not possible to pronate, and generally better suited to display or aerodynamic functionality. So I think the horizontal spine and long, relatively stiff tail would probably be there to stay, and the limb anatomy and use would heavily favor the use of the jaw and legs as manipulators, not the arms.

Changing the number of limbs isn't that rare. Snakes, whales, amphisbanians, etc all lost limbs, as did some therapod dinosaurs. Gaining limbs isn't rare either. You just need to look at clades where limb count is heavily tied with body segment count. Limb count isn't a reliable method of identifying relationships between centipedes, millipedes, polychaetes, and isopods. Even caterpillars have pseudo-limbs in addition to their six true limbs, then lose them and grow 4 more limbs (wings) as adults. What is rare is for limb count to increase at a species level or greater in a clade that do not undergo complete metamorphosis and who's limb anatomy is separate from duplicated body segments. I.E. vertebral segments in tetrapods have nothing to do with how many limbs they have. It's still worth noting though that while limb count is unlikely to increase in these species, it's still not impossible. Lizards have evolved wings from their ribs multiple times over. Snakes have evolved to turn their entire body into a wing by modification of their ribs. It is entirely possible that the evolutionary process of limb genesis can reoccur in limbed or limbless organize creating new types of limbs on their body that do not share morphology with their existing ones.

One thing about loosing fur in humans, we not only lost fur because of fire, but because we can sweat. This allows us to cool out body while running, even in great heat of a savannah. Other crratures with fur overheat and get exhausted way before humans tire, which gave us an advantage while hunting.

Worldbuilding made easy : A deity made them that way.

The drawings you used for the reptile, bear, a humans look a lot like hero forge models. Personally I think the bears would have more of a rectangular or round torso due to the fat they need to survive in such cold environments rather then the small human like waist tapering up to a jacked chest and shoulder region. I also think the lizard people look a bit too human as well, I just don’t know enough to put my finger on it.

Wouldn't the octopi seek a permanent host, though? What started as a parasitic relationship turning into a symbiotic one, with the octopi evolving the nervous system and the host species evolving the physical attributes.

There is a point we inspect zoo bring out a lot. Evolution prefers to adapt existing things rather than create new ones because it's limited to the base blueprint it's working with and the greater the change the more energy it requires. Since gradual changes can result in considerable changes over time and take less energy for the creature gradual changes tend to result in new things being adapted from old things rather than things being created from scratch.

Glad to see your subscriber count increasing with each video. You make good content and deserve a following.

One thing I wonder is the likelihood of a strictly carnivorous sapient species ever needing to make fire. I feel the main utility of fire for humans is to cook meat and make it safe for us to eat, but since specialized carnivores tend to have more acidic stomachs better at handling rotten meat, they wouldn't need to cook it. I suppose it could still keep them warm at night, but that would only be a priority in cooler climates if they didn't have a thick fur (or feather) covering.

As a biology graduate who studied ecology and is a hobbyist worldbuilder, it's refreshing to find someone who mentions sexual selection in their species evolution. It's a major factor in evolution working in conjunction with (but often to different ends than) natural selection. One thing i did notice though is the presumption that your viviparous species would necessarily give birth from between the hindlegs. While it's common in terrestrial vertebrates for the genitals and excretory systems to be anatomically adjacent, that's just an accident of evolution. As invertebrates show, it's perfectly unremarkable to have your genitals on other parts of the body, even on or near the head, and for them to be unassociated with the excretory systems. I guess it makes sense for vertebrates to have the womb in the abdomen as there's often no parental bone structure restricting the growth of the foetus(es) there and in a quadruped it makes sense carrying them ventrally as a predator is more likely to go for the flanks or back that are more exposed, but evolution could just as easily have put the birth canal under the diaphragm as between the legs. I guess between the legs makes it easier for quadruped mammals, but it's a position that evolved before we left the ocean when fertilisation didn't even occur internally and it's particularly cumbersome for many reptiles and birds to mate because their cloaca is under their tails. Having seen the fight birds and big reptiles have to get everything into the right position for long enough for insemination to occur i dread to think how bad the big dinosaurs must have had it. Had evolution gone slightly different and the birth canal in vertebrates *was* below the diaphragm it might have made things a little easier for birds and reptiles (though big guadruped dinosaurs would still have had problems).

One thing I like doing in my world building is remind people that even if ocks dwarfs and elves look human but thy vary much are not. In my world's elves are often powerful cat and raptor like solo hunters with exactly good sciences compared to humans. Acting more like hawks in human form then people.

For your plains runners, there is no need for them to become upright standing. Having a tail to balance yourself while already being bipedal is more energetically efficient than what we humans have. We are only upright standing because we *didn't* have tails to balance with when we were freeing up our hands. Our endurance is so good, not because we are upright, but because we can sweat, which cools us actively while we are running. That is also why we lost our fur, to facilitate sweating. It's very likely that those lizard guys would remain horizontal, but have upright heads :). Maybe their feathers would have an oily substance which, when flared out, allowed for really good heat exchange with the air, or something. The bears are more accurate, as they also have no tails. Our pelvises became really small to support our uprightness (with women needing the smallest possible hips that are just large enough to manage giving birth). Though, their female's breasts wouldn't likely be in the same spot as humans. Grizzlies for example have 6 teats, with four on their chests, and two just above their groin. Furthermore, you need to account for the reason that human women look the way they do when designing the sexual features of this bear species. Pimates are hugely attracted to rear ends. Mandrills, baboons, chimps, and many other primates have sexual selection pressures to have eye catching butts. For mandrills, it's bright colours and prominence through posture. For humans, it's smoothness and jiggliness. Male eyes are really well adapted for seeing micro movements, so women have a lot of fat on their rears, as well as permanently enlarged breasts (which are rather rare in mammals). Bears likely have different hunting specializations than humans, so their eyesight is good at different stuff. They're good at seeing colours for foraging, and movements obscured by water for fishing. Female bears might develop features on their face, teats, and hips to attract males. This might be lighter colours, intricate patterns, or even long and soft, translucent fur which mimics white water rapids. I *REALLY* dig your octopus idea! The concept of an intellectual parasite is incredible, and is a really cool way to spin the anatomical strengths and weaknesses of the species. Very well done, and a really cool way to encourage uniqueness due to physical differences from other animals!! There are all sorts of cultural implications that come from such a different style of life that would be really cool to explore. Super sweet video overall, and I appreciate the effort :)! I know this video is old and this comment likely won't be seen, but I'd be very interested to hear yourthoughts on what I've said above! Thanks for the solid stuff, dude! Keep it up :)

you just explained the evolution of the D&D illithids to some degree.

I find settings with both humanoid and non humanoid sapients as the most interesting, as it gives you both the familiar and the alien to work with within the same story. Similar to how the Charr are in Guildwars, and even they are on the more humanoid side. So a little sad to see the raptors develop as humanoid as they did, though I understand the reasoning in the literary sense. And you did at least maintain the Na'qwuil as quite different from the other 3! It does feel like a bit of a drop off cliff though instead of a sliding scale.

YESSSSS!!!! Finally this video is here!!! Words can't say how much i love your channel, Matthew You deserve more viewers

idk why but i really like the juxtaposition of having bear-people and lizard-people, and then horrifying brain squids that require humanoid hosts

One point: we actually have a lot more hair than you might think. It's just that the width and length of those hairs have reduced drastically in order to make room for our oversized sweat glands. The pest question is another factor, but it's far from the only one.

The brain of a cephalopod isn't under the mantle. It wraps around the esophagus and then runs down each arm, giving them a number of brains one more than the number of limbs.

As a fan of speculative evolution/biology and as someone that has created dozens of species in his own worldbilding, I wanted to say that I find Your video quite interesting and creative! And it was cool to see another person besides Me coming up with mind parasitic not-illithids. :)

"that kind of intelligence won't go on to have plants founding the internet" Do mycorrhizal fungi networks count?

Stumbled aceoss this video earlier today, and was so intrigued by this world and the amount of thought put into it that I paused and binged the entire series up to here before continuing. A subscriber well earned, sir.

Ok but suppose your intelligent organism evolved from a hoofed biped with a stabilizing tail, wings for display, control when running, and incline running but not true flight, and a prehensile trunk? I think it is much more likely that the trunk and lips and tongue are used as manipulators and not the wings, tail, or feet.

Na'qwuil are a pretty good way of getting Ithilids/Mindflayers. Nice! Not sure I fully agree with the Silarin's final bodyplan. Feels like it's a little too anthropomorphic.

Note: sea lions do not have fins, they have flippers. Fins are structurally different, and are seen on fish.

You have an amazing, simple but informative set of videos for worldbuilding that should have more views not just to support your channel but to help other worldbuilders in their projects.

I found this series with the magic system video and thought I'd try to rebuild my draft world with these steps. Now I'm simply ignoring my notes and enjoying your world.

You might find it interesting that a lot of recent research has been done into how cultural development provides selective pressures for genetic enhancements which provide further selective pressures for cultural evolution, ad infinitum.

Evolve on land? There's evidence that Ancestors diverged not just by leaving Ocean for Land, but in some cases once more leaving land. i.e Dolphins said to have at some point said eff the land, dude it's horrid. I'm going back to Mother Ocean. Als there's a theory about Swamp-Apes too. So in a world of Fantasy that has to be factored in if you want Mer-Folk etc.

Explaining in a highly scientific sounding manner, why the bear-people would absolutely have boobs and big butts is the biggest, yet most accurate excuse for making your furries sexy that I've ever heard xD

I just need to point out the absolute insanity that is the fact that the ancestral dinosaur was bipedal… meaning that all quadrupedal dinosaurs *secondarily evolved said quadrupedalism…*

8:32 I think scavengers would be more likely to produce sapient creatures, while predators certainly could I just think scavengers have a greater chance of leading to sapience. The reason I believe this is because the humans' Ancestors were scavengers, and well we're the most sapient creature on our planet, and then there are ravens who are the most intelligent species of birds, also scavengers

The humanoid bauplan obviously works for a sapient being, but many aspiring worldbuilders take that as an excuse to populate their worlds entirely with various variants of humans. Pointy eared humans, small humans, humans with scales or fur, snake headed humans, and so on. They don't even try to add more outlandish sophonts which is a huge shame. Just copying reality makes for realistic, but often boring worlds. Exploring the consequences a different body plan can have on a civilisation can be a lot of fun and result in truly unique fictional societies. And exploring how two or more vastly different species might live together in the same world or even the same multi-species society is even more interesting.

Select your species: Monkey => Human Giant Velociraptor => Silarin Bear => Urakan Octopus => -The unholy offspring of a Dalek and a Mindflayer.- Na'qwuil

Herbivorous creatures can also gain sapience. Take elephants for example. They have culture, and cultural learning. Sheep are intelligent as well. When a species is prey there are two main paths of adaptation leading towards evolution. Getting bigger and more aggressive as to fend off/ intimidate would be predators; or gain intelligence to defeat them. Herbivores also have the benefit of having a more reliable source of food. The need to expend less energy breaking down plant material would drive them towards fire/ cooking.

That squid race & that parasitic skill is basically the Oktigi from Oddworld... thats terrifying

Jesus, those bears would be terrifying. Imagine having to do battle with an army of 9 foot tall warriors with double the weight and strength of a human. It would be tough to even beat the females 1 on 1 because they're built like a hairy, female verson of the Rock.

First of all, liking this channel a lot. It's of course not universally applicable, but I have been able to put this to some use already to reinforce otherwise super unstructured worldbuilding. For this video, while I was obviously curious and generally like the results, there are a couple things I feel I should note or second: 1. In regards to the Silarin: I feel like this is the one that makes the least amount of sense from an evolutionary standpoint, for reasons I also saw in the comments. The Callidus are _already_ bipedal, and if I get this correctly, you also _already_ made them endurance runners. In other words, outside of getting prehensile talons, there isn't much the Silarin needed to change physically, nor do I think they need to become completely upright (rather, a slight hunch could be maintained). Not that human physiology doesn't make sense, it only doesn't because raptors are already good runners. 2. Somewhat related to this, while simian to human evolution makes sense, there is a bit of a hiccup with Nota to human: This evolution would occur in rainforests, where arboreal movement is perfectly viable. Contrast with earth humans or locus Silarin, which _have_ to run because savannahs have a lot less trees, and thus would have reason to improve their running game. Locus humans, by contrast, have no immediate reason to evolve this way, unless maybe you stuff the rainforests full of harpy eagles or some other threats above the ground, so that closer to the ground is the safest place to be. Still, they're humans, and I agree humans are handy to have for reasons you described. 3. The Urakan make a lot of sense. Being bear-based, they grow to permanently adopt bipedalism that they already used in short bursts, rather than changing an already suitable biped form. 4. The Na'qwuil are also logical, but one thing I immediately had to wonder is if strength or manipulation would be their main issue on land, as tentacles are _a lot_ of muscle. Rather, it would be stability due to no bones, as well as lackluster speed on land, which octopi would be able to make up for somewhat through their elaborate camouflage capabilities. I still like the Na'qwuil, but I feel the arguments for why they would struggle are off. Also, I hope they do eventually become less parasitic as their civilization further develops, because having an obvious disregard of other life will cement them as enemies in the eyes of basically every other sapient race, which means they either need to _royally_ compensate for this huge amount of enemies, or die really quick. Writing this down also helped me realize that trying to follow evolution is probably not a great idea in my personal opinion, especially if you're going in a more fantastical direction anyway. It places _huge_ constraints on what you'll be able to do with your sapient creatures, even if we expand beyond the chosen source species in this video. That does not seem desirable unless you need these constraints to get going. I myself don't follow evolution in my process. To be precise, evolution would be possible in my world, but it is typically outpaced by dimensional rifts that create new life (among many other effects).

You need to be bigger, I'm glad RU-vid recommended you.

I love how I watched the number of subscribers increase as I binge watch this series over the course of the day

A Few Lizards do live birth so a lizardlike Sapient could have live births & breasts :) Also a key point is that though there are certain lineages on Earth ...nothing is absolutely set in stone. Eg it is possible for a Mammal to lay eggs & then also have babies suckling after hatching eg Platypus. In my world I took the Platypus and extrapolated that to a lizardlike ancestor of my Lizard-Folk. The Traedi lay an egg after three months gestating, then the mother broods the egg for three months, then the hatched baby suckles until teeth come in & it draws first blood by it's bite then that awakens the baby to want chewed meat brought by father and mother.

Some very intriguing information and ideas! I just discovered this channel and am rather curious now

In order to implement sirens in my world, I considered that they evolved from the same branch as humans (that would explain their appearances and the ability to develop intelligence as they are outside water). One of these pre-human communities evolved closely related to the water, so they developed aquatic features until one part of these went full siren (just like whales evolved from terrestrial animals). I'm still unsure on how to develop intelligent fairy-like creatures though, mainly due to their tiny heads

Caveat: creatures like the related octopus, squid, and cuttlefish exhibit a degree of both radial and bilateral symmetry, but it could be argued they are more radially symmetric. However, they also evolved along an axis, and have single or paired organs (siphon, eyes, specialized tentacles for breeding). It could be possible for a group of their limbs to be "legs" and a group to be "arms" with not too much reworking. And starfish, radial symmetry, might have something similar. So we need to be careful giving absolutes, because not only could things evolve on Earth, but they might evolve very differently on other planets. Also, from a couple of recent videos on early biology of vertebrates, it might be possible that instead of five fingers/toes, early land animals could have ended up with six or seven per hand/foot (polydactyly is still a thing too.) and even six or eight limbs rather than fou was apparently a possibility from the early animals that moved from sea to land. I can think of at least the aliens in the Footfall novel as having dual prehensile trunks from their heads which I think also had opposable digits at the end of the trunks (it's been too long since I read the book to be sure of how they were designed, elephant-like but at least two or four trunks, then dividing into finger-like digits, I think it was.)

A big element I try to keep in mind for my (fantasy) worldbuilding is the factors of the world that are wildly different from Earth, or any hypothetical real planet that is likely to exist, the most pressing for most fantasy settings being magic (depending on the system, of course). If there is an ambient magical force on the planet, and animals don't harness it, why not? Why would they not practically all evolve to do so? And if an animal is going to evolve sapience and advance tool-use, and it has access to telekinesis, for example, does it even need a prehensile appendage? If telepathy exists, does spoken language need to exist? Also I appreciate that your setting basically has the Elder Scrolls races: Humans (Humans), Khajiit (Urakan), Argonian (Silarin) and Elves (Na'qwuil).

Intelligence actually seems to develop more from omnivores than carnivores. A predator has no great need to develop intelligence, because its strategies vary little, either ambush or endurance. Omnivores OTOH need larger memories, which means larger brains.

you say a relatable and loveable alien should be humanoid, but i counter with Rocky from Project Hail Mary.

One thing I hate to break to you is that losing fur doesn't reduce the likelihood of parasitism. Humans are affected by a wide variety of parasites including those that would normally only be associated with fur-bearing mammals. What's more, our sweating renders us more vulnerable to certain types of parasites.

Have you heard of the Portia family of jumping spiders? They can learn, remember, and problem solve. At least Portia Fimbriata if I remember correctly

Ehm... Why cominicating with colors is somewhat worse that cominicating with sounds??

If you are building a world for your own entertainment, just because you like building worlds, you don't have to include humanoid creatures. Thinking and imagining just to think and imagine. Brain exercise.

really excited to see where this is going!

The most important trait for a species to cooperate on a large scale is fictional storytelling. It's humans' ability to believe in things that aren't real, like Gods, corporations, nations and money, that allows us to cooperate on a large scale. Yuval Noah Harari writes about this extensively in his book, Sapiens. In other words, storytelling, including world building, is the human superpower which gives us dominance on Earth.

For sexual dimorphism on mammal like animals. If you look to mammals there is a large variation of sexual dimorphism, gibbons have far less sexual dimorphism, being considered monomorphic. So you can have fun with it; it's all plausible. Though having a certain level of sexual dimorphism is more likely, and human level is a decent level without forcing male and female to not share certain role, so a female or male rich society (due to what ever) can come back, while having enough sexual dimorphism that sexual divided roles are still likely. If the species as no sexual dimorphism, there is a high chance that there is little difference between gender on roles, and probably feeding could be done by male and female (oh and even if you have sexual dimorphism, you can have to male deal with lactation, like some bat does). If a species has heavier sexual dimorphism, like let say males are half the size of female, then there would be a huge sexual role differentiation, potentially one sexual could not be fully sentient, while the other is... It would have massive impact on culture and religion. But also on the odd of survival, due to a role not being able to filled by the other gender, and if something happens to a lot of on gender, it could lead the the downfall of the society... So having a sexual dimorphism that is on the human is just simpler, likely, and I think it's probably easier for the target audience...

Disagree with a lot of your processes and results. Saying Perilux color language would be less fertile soil than auditory communication for abstract language-why? Signs might not go around corners, but they don’t make a sound, and that might be highly useful for a eusocial prey species, especially under environmental pressure that could select colonies for cleverness. And “brain size threshold”? Have you heard of corvids? Have you met the parrot Alex? Regardless, love the video. It inspires me to go about this in my own way.

Once again tails would not necessarily only remain coz of sexual selection, but could've co-evolved as part of their protection against bigger dumber Predators, in their Hunting & in Territorial/Mating fights with other Males ...eg tails could have Spike or Hammer Bone or Rattle which they use in hunting, combat or threat/challenge/warning. Also if in some areas their prey lives in top of trees the tail could be prehensile in order to climb/move through trees. You could have different tail types as different sub-species depending on envioronment/biome. The Lizard-Folk of the coast/swamp/river have tail which helps them swim, the Lizard-Folk of the Southern High-Grass Plains have Warning/Stampeder Rattle, the Lizard-Folk of the Forest borders have a tail adapted to climbing, The Lizard-Folk of the Northern Low-Grass Plains have a Hammer Tail to deal with giant Predators/Prey, another group has Spike to kill a certain type of Prey...

Your gauging of brain size only on volume is a flaw. It's partially brain to body ratio, but that ratio is more closely tied to cell numbers not volume or mass. Bird cells tend toward being much smaller, possible because of a small genome, and so more cells can fit into a smaller space. Tool using appendages don't have to be hand, but they do need to do three things; pinch grip, cylindrical grip and spherical/radio grip.

Every qualifier for sapience is found in animals too, primarily thinking of citations (whales and dolphins), octopuses, and corvids (ravens, crows, magpies, etc.). There isn't anything unique to humans, it's only more developed.

I am extremely confused on your reasoning to make the endurance runner Callidus into the upright Silarin. At 14:36, You state that bipedal creatures bio-mechanically use less energy when standing upright, but never explain your reasoning for this assumption. The Callidus were already bipedal, only using their hind digitigrade talons to run and I'm assuming using their wings to provide aerodynamic forces either for more traction or for pouncing on prey. Why would the Callidus ever evolve this body structure to begin with if being upright uses less energy? For my own speculation, I believe that it's not bipedal creatures that use less energy when upright, but tail-less bipedal creatures that use less energy. A tail would act as a counterweight, and might even make the creature more stable than a tail-less by putting more mass away from the center of mass, increasing the creature's moment of inertia, which means a greater torque would need to be applied for the same angular acceleration. You even stated at 14:53 that the tail was used for balance, so you were thinking of something at least similar to this. So why make them upright? Surely there wouldn't be evolutionary pressure to just gradually become more upright over time; becoming more upright would increase parasitic drag, which would only weaken their niche as endurance runner pack predators. Maybe you wanted to free up the wings so that their aerodynamic functions would no longer interfere with the actions of their prehensile talons. But why would the wings be the limbs to give up their function if they're already so important to the Callidus' current niche? Sure, the Silarin final state fits a new niche and is just as viable as the Callidus, but everything in between just seems like it wouldn't work, there doesn't seem to be a viable evolutionary pathway for those adaptations. I imagine it would be much more likely that, while the talons on the wings to become more developed, the wings themselves stay relatively the same, and that the Silarins as a result are better runners than the other sapients, but have less capable prehensile limbs as a trade off. Even still, at 6:00 you state that prehensile limbs are much more likely to form at the end of limbs as opposed to other appendages. You don't state a reasoning for this assumption either. I assume it's because other appendages already have important uses for the animal and that limbs are more adaptable, but in this case, would that assumption hold? Both their legs and wings are used when running, yet many birds in our world that show tool use, use those tools with their beaks, something that isn't used when running. I would think that would make the beak the much more likely appendage to become prehensile, maybe even along side the more limited prehensile wing talons. I think that's an even more interesting species to speculate and world build about: A sapient bird species that has 3 prehensile limbs, but each are less capable than the other sapients. You could really dive into how this changes their society, I imagine the ergonomics of tools, furniture, and architecture would vary greatly with our owns. I guess a lot of it still comes down to what you said at 9:02, that people connect more with people. Maybe it's just your preference to have very human-like sapient races, and there's nothing wrong with that, beauty is in the eye of the beholder. But the way it was presented in the video made it seem like a rule that you had to make everything humanoid otherwise people won't like it. It made it seem that anthropomorphizing the Callidus so much is trading away something that could be amazing to take the safer, boring route, and left me feeling rather annoyed after finishing the video.

you should have split the monkeys, so not only would you have humans, but you could have tree goblins as well. :P

I kind of find elves and dwarves boring... The closer to humans a creature is, the less novel it is; there's also the possibility of the uncanny valley... On another point, manipulators in fantasy don't have to be physical; the moment magic or psychic powers are introduced, the ability of a house-cat-like creature to manipulate tools without even touching it becomes probable... And if hyper-specialization in magic is more efficient, provides higher maximum power, or provides more utility; at least compared to physical manipulators... Then you can imagine non-humanoid looking creatures might be more common.

I doubt I'll get a response here but did anyone else notice his diagrams for the humanoid versions of his races are literally just tracings of the dragon people from Heroforge? Well played, honestly a little jealous I didn't think of it first!

I did a fanfic of Locus where the the Leonix evolved into the Lejon, arctic catfolk bassically and their language is based of irl swedish

Matthew: 9:03 Me: Come on, Na’qwuill! You’re the best!

13:17 I'm sorry this is just audist. Look up sign language, it's incredibly complex and entirely visual.

I have to wonder though. Why is a head necessary exactly? Couldn't you develop a decentralized nervous system in a creature? It would be weird but I don't see why it shouldn't be possible. The creature may have poor reflexes, and losing certain parts could lead to severe mental damage as well, which would not make it super good with natural selection, but I don't think it would be impossible.

I think omnivore is more appropriate term for sapient species requirements. The variable sources of food should make those guys creative. Also I see no possibility for several sapient species to evolve on the same continent. Sapience is so enormous advantage that the first species to win that evolution race inevitably wipes out all and each of its competitors. We see that even close human relatives gone extinct due to rise of humans. So gone are the megafauna and innumerable smaller species. Only African species more or less survived because they evolved beside humans. The only thing that managed to avoid extinction in our ecological niche are wolves, but they were lucky to have big brain, social structure and ecological adaptability

The Hero Forge assets are cool.

Great video! I can see you getting more in-depth about how the races look. Maybe the Urakan get darker fur in warmer climates with the females wearing decorative corsets, as that's where their nipples would realistically be. Maybe the Na'quil take advantage of their ink and sharp tentacles to tattoo themselves. Humans and Silarin could use plants for cosmetics; just imagine Silarin wearing kohl to protect their eyes from the sun.

8:04 I know you said the originators of a sapient species are likelly to be predators and it's true that mammal and bird predators are generally more smart than the counterparts, but this is not even a strong relationship, the smartest group of animals are generally considered to be Primates, consisting with omnivores and herbivores, the smartest birds are crows and parrots, respectivelly omni and herbivores too, you may consider the elephant an exeption but they also have a free prehensile apendage with fine motion control, I know all cetaceans are carnivores, but despite their intellingence, they are kinda stuck with no prehensile limbs and won't harness fire. The hypothesis that sapient species would likelly come from predators makes sense but it's ultimatelly unfounded, the only sapient race on earth comes from omnivores after all, I don't find a refutation on the theory, I just think the pressure of predators being more able to attain sapience is not that big

good video 👍 ...but permanent Breast aren't likely to develop in other humanoids.

I don't see visual language as a limiting factor.

Calling the octopus-like species "weak" tells me that you know nothing about cephalopods. A 2lb octopus has more strength in one arm than you do in both.

Goauld-like octopus. That will be really interesting 😂

This will be useful, as I'm still building up the biology of my world chronologically. Though I have evolved the first protodragons already. While my world has 3 main sapient creatures, humans, elves, and beastfolk(later falsely referred to as demons in my dream game), there will be many other lesser sapient creatures. The 3 are practically one species, almost like how huskies, chihuahuas, and pitbulls are drastically different, they are all breedable. But through evolution, using mana to supplement growth, and even a process I call magical endosymbiosis, many others will appear.

Had a giggle when I noticed the Hero Forge models. Awesome.