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I have got a fictional universe, where a humanoid lifeform evolved on earth not from apes, but from bears. The humanoid bears are like humans; they walk on their legs only, wear clothing, have various languages and civilizations; the only thing is that they still have snouts like bears have and still have fur on their whole bodies.

What could be a good PoD or event which would prevent Apes from becoming Humans and would instead let Bears become humanoids?

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    $\begingroup$ The thing is that bears have never had a need for any of the attributes that make us human because of their incredible physical prowess. Humans developed tool use, society-focused drive, large brains, and sweat glands to make up for being so physically weak compared to apex predators (like bears). I think you need to start with an overall weaker bear and force them to adapt accordingly, because bears in their current state are pretty incredible from an evolutionary standpoint. Also, why would bears wear clothes? That's the biggest question to me. $\endgroup$ – Shollus Feb 16 '15 at 18:32
  • $\begingroup$ @Sholius If you look at an an ape, covered in fur in the tropics, and ask, 'Why would apes wear clothes?' you would be asking a silly question. Just because non-intelligent bears have lots of fur doesn't mean intelligent ones will. $\endgroup$ – kingledion Oct 25 '16 at 13:11
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In order for bears to become humanoid tool users, they'd need to evolve a few things first:

  • Tool use
  • Dexterous hands
  • Abstract spoken communication
  • Group living
  • Bipedal stance

Notably, all of these but the last one are found in non-human primates, though the adaptations towards abstract communication and tool use in something like a chimpanzee aren't evolved to anywhere near the degree they are in humans. Bears, on the other hand, have none of these things. As it currently stands, apes are closer to evolving into bear-like humanoids than bears are.

We do, however, see at least one of these adaptations in one specific kind of bear: pandas, which have thumbs. Sort of.

enter image description here

In order to better grasp bamboo, pandas have evolved thumb-like spur on the side of their wrist which they can oppose the rest of their fingers against to grasp shoots of bamboo. This is the sort of an adaptation that could one day lead to a dexterous hand. Some pandas could, for example, begin to use bamboo shoots as tools to knock nests, low hanging fruit, and bee hives out of trees. If they lived in a place that had lots of these sorts of things for food, and in which bamboo was becoming more scarce, using bamboo shoots as tools could be a natural way to increase the amount of protein in their diets.

Next, if our mutant panda environment was relatively rich in food, our pandas might begin to see more benefit in hanging around as a group instead of going solo. Since they wouldn't need a large gut for digesting lots of cellulose they'd also begin to get slimmer, at which point bipedalism might allow them to reach more food and better manipulate the sticks they're using to access their food. At some point, they might begin to try throwing their sticks to get things that are out of reach.

All of this would take a long time, as well as some ideal conditions. Pandas are far from stick-wielding bipedal fruit-knockers, but it's possible they could evolve to be as such. All of this would put them in a position where they could develop into something we regard as a sentient species, though.

They would, however, have some distinct differences from humans. For one, they would probably be terrible runners. Pandas, as it currently stands, are pretty slow, and the evolution towards bipedalism we're looking at is not an evolution for bipedal hunting. If they did hunt, it would probably be by throwing things.

Our panda-people would have much stronger arms, even proportional to their size. Their main means of getting food, at least early in their evolution, is to whack things in trees with sticks. The bigger their muscles are, the bigger the sticks they can use.

Lastly, they probably wouldn't wear clothes. Pandas are quite furry, so clothing wouldn't be necessary in most environments.

Why wouldn't ground dwelling carnivorous running bears become humanoid

Most animals in history have evolved without humans and never become humanoid, because evolving some or all of the traits that define a creature as 'humanoid' is not evolutionarily viable.

By evolutionarily viable, I mean that every step of evolution (generally) leads towards a form which is better evolved for survival. Apes, for example, developed progressively more dexterous hands because at each point during their evolution, increased dexterity lead to improved ability to climb trees. Eventually, these dexterous hands allowed chimpanzees and early hominids to begin creating and manipulating tools, but they were only evolved in the first place because every step along the way improved their ability to climb trees.

For ground-dwelling bears, the primary purpose of feet is for walking, and the primary purpose of front legs is for supporting body weight. Hands, unfortunately, aren't terribly good for walking on the ground on. This is why we humans have stubby little toes. In order for paws to develop into hands, grasping must be more important than walking. Pack dwelling bears that ran after food on the ground would develop hand-wise in the opposite direction, with fingers becoming progressively shorter and stouter.

Bipedalism follows a similar trend. While paleontologists are still divided as to exactly why humans became bipedal, it certainly wasn't to help a ground-running predator catch food. The transition, at least initially, would have led to slower creatures than those which ran on all fours. If running quickly were important, natural selection would have selected for the quadrupedal creatures. Modern theories posit things like the ability to carry food or the ability to pick things off of low branches as being the reason for developing bipedalism. For bears to become bipeds, something similar must happen with them. It must be more beneficial for them to stand on their back paws while using their front paws for something else than it is for them to run on all fours.

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    $\begingroup$ How about Koalas? 2 thumbs up! $\endgroup$ – Serban Tanasa Feb 15 '15 at 23:45
  • $\begingroup$ But you know, it was mainly the humans that prevented bears and other animals from evolving into humanoids. I am thinking of bears entering the niche of humans. Maybe first, they would start living in groups, so that they could hunt much better, this means they would get more protein by eating more meat, which will reflect in larger brains, and more advanced hunting, which will in the end lead to attaining a bipedal stance so that tools can be used for hunting. Maybe throwing entire tree-stems at unsuspecting animals or at concurrents? $\endgroup$ – MedwedianPresident Feb 16 '15 at 14:50
  • $\begingroup$ @MedwedianPresident Ground hunting animals probably rely on running too much to develop dexterous hands and bipedalism. I added another section to my answer with a longer explanation of this. $\endgroup$ – ckersch Feb 16 '15 at 19:09
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You would need to go back a long way, probably about 4-5 million years.

There is little debate that animals in the genus Pan, made up of one species with four subspecies of common chimpanzees (Pan troglodytes of the Western, Nigeria-Cameroon, Central and Eastern varieties, in geographic order, with a substantial gap between Western chimpanzees and the continuum of the other three subspecies, with some zoologists preferring to split Eastern chimpanzees into separate Northern and Southern subspecies rather than lumping them into a single subspecies), and one species of bonobos (Pan paniscus) aka pygmy chimpanzees, are more closely related to modern humans than any other species of animals that still exist today. Common chimpanzees have 23 chromosomes, bonobos have 24 chromosomes and modern humans have 26 chromosomes, but the chromosome divisions are such that particular genes in modern humans usually have corresponding genes, sometimes on a different chromosome, in chimpanzees and bonobos.

There are roughly 170,000-300,000 common chimpanzees and 30,000-50,000 bonobos alive today. The 30,000-50,000 population of each of the chimpanzee populations today is probably a pretty reasonable estimate of the total population of species ancestral to modern humans while they were confined to Africa.

Lots of disasters and misfortunes (volcanos, floods, wildfires, disease outbreaks, droughts) can send a relatively geographically compact population of that size into a tailspin. Indeed, several species of hominins ancestral to us did go extinct over the last several million years.

The divergence between other great apes like chimpanzees and bonobos on one hand and hominins on the other is on the order of 4 to 7 million years ago, with more recent data favoring the older date which is when the earliest hominin fossils are dated. There are several possibly ancestral and possibly sister hominin species in this tie period in Africa.

The six million year old Orrorin is arguably more human-like than Australopithecus (e.g. Lucy) despite being about 3 million years earlier. Sahelanthropus tchadensis, which is about 7 million years old, has been classified variously as a common chimpanzee-human ancestor, as part of the genus Ardipithecus (which is about 4.4 million years old), and as the ancestor not of humans but of gorillas.

enter image description here

An artist's depiction of Ardipithecus.

The oldest member of the genus Homo is Homo Habilis (an artist's depiction of which is below) dates to about 2.33 million years ago.

enter image description here

The first hominin species to leave Africa was Homo Erectus ca. 1.9 million years ago in a single migration wave. Homo Erectus is the hominin species that in terms of technological developments we associate with comic book "cave men", using stone tools and fire and clubbing big game and living in natural caves, but any clothing used was probably pretty primitive because their range extended much less further north than Neanderthals and modern humans who came along later and are derived from a common ancestor well after Homo Erectus.

The effective population size of the Homo Erectus out of Africa migration wave was probably pretty modest and all manner of misadventures could have prevented them from making it out of Africa. One or two encounters with giant crocs in the Nile or sharks while trying to cross the Gate of Tears if they took that route, could probably have done them in if they weren't lucky.

But, once Homo Erectus was out of Africa the window of opportunity for bipedal bear evolution pretty much closed because that ecological niche was now filled.

(Honestly, a scenario with an "inferior" Homo erectus or Ardipithecus species that didn't leave Africa, and a bipedal bear species that only entered Africa ca. 50,000 years ago, might be even more interesting than one in which there is no evolution for hominins at all beyond chimpanzees, or in which later hominin species go extinct.)

Your divergence date pretty much needs to be prior to Homo Erectus, or at least prior to Homo Erectus leaving Africa, as it becomes increasingly hard for Homo Erectus to go extinct at that point (although competition with humanoid bears could conceivably wipe them out), and as it probably takes at least 2-3 million years for bears to evolve from being bears to humanoid bears. Really though, the bears we have today are closer to Ardipithecus in terms of their level of humanoidness relative to the bipedal bears you imagine, so a divergence date more like 4-5 million years ago would probably be closer to the mark.

During the Upper Paleolithic era (ca. 40,000 to 10,000 years ago), before farming and herding were invented, bear migrations and modern human migrations pretty closely coincided, so modern human prehistory can be a pretty reliable benchmark for prehistoric bipedal bear migrations. (The earliest archaeological evidence for modern humans out of Africa is about 130,000 years ago, but genetic evidence suggests that all non-Africans today have a common ancestor ca. 75,000 to 50,000 years ago).

We address several unresolved issues regarding the Late Pleistocene demography of brown bears: (a) the putative locations of refugia; (b) the direction of migrations across Eurasia and into North America; and (c) parallels with other mammals, including humans. We present results based on more than 200 complete mitochondrial genome sequences from Eurasian and North-American brown bears. Bayesian phylogenetic analysis revealed that most individuals belong to a very large Holarctic clade. The MRCA of this clade lived ca 40 thousand years ago, most likely in the Altai-Sayan area, a known Late Pleistocene refugium in Asia. We propose several migration scenarios for bears and suggest that brown bears and humans underwent a series of parallel migrations in Eurasia and to North America during the Late Pleistocene. Moreover, both species exhibited a demographic standstill in Beringia before colonizing North America. Synchrony in the timing of past migrations and standstill implies that the ecology of large mammals includes key limiting factors that can enhance our understanding of ancient human movements and on large carnivore conservation.

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