48
Dolphins. They have brains as big and as active as humans, eating only fish and other sea creatures. They have tactics and strategy and possibly even limited tool use, and some scientists believe they are also sentient and sapient.
Sure, their sapience is not a scientific consensus (yet?), but at least it is discussed as something that can be true, and ...
37
Not everything has to be directly driven by adaptation.
Consider everyone's favourite mammal, the Naked mole-rat. They live in low oxygen, high carbon dioxide tunnels and have to deal with inconveniences like occasionally tunneling through a nest of angry ants. Result? they're extremely pain insensitive, can not only tolerate atmospheres that would kill ...
35
The Earth had life without multicellular animals for roughly three billion years, so it should be pretty obvious that such a planet is possible. There were certainly plants for some of that very long period — the amount of time depends on your exact definition of a plant. But there has been photosynthesis for nearly as long as there has been life.
33
It's not necessary, but it does help
Nutrient-wise, it isn't impossible to grow a big brain on a one-note diet (a high-fat diet does make brain development easier, but in an environment where nutrients are readily available the lack of meat isn't going to be a deal-breaker), but the main benefit of intelligence is the ability to adapt one's behavior - ...
31
if it were an obligate carnivore (like an axolotl or a penguin), it would not have enough carbohydrates to turn into electricity.
This makes absolutely no sense whatsoever. Protein is actually very beneficial for brain growth, in particular neuron density. Big cats are obligate carnivores and highly intelligent.
Carnivores like canids and lions are also ...
30
Completely Plausible
Evolution has shaped the odd-toed ungulates into incredibly diverse forms, consider how different the ancient ancestors of the horse were, or how diverse the rhinoceros family was in the Eocene.
Every trait you gave for the Elasmothere descendant is rather straightforward, the fur can change due to environment or sexual selection, ...
29
Whales and Elephants and Orangutans
Whales are purely carnivorous and Elephants are purely herbivorous. Orangutans are almost exclusively herbivorous. They all have big brains and, along with the other great apes, are widely considered the most intelligent classes of animals.
Orangutans are usually claimed to eat mostly fruit. But it's hard to find a ...
26
It may interest you to know that some of the earliest animals on earth were largely invisible to night vision goggles in the first place, and that later animals have actually evolved to be visible in night vision. The secret, as it turns out, is to be cold blooded. We'll get to that, but first let's deal with camouflage...
To begin, we have to understand ...
26
There are basically two main evolutionary drivers:
1. 'Survive long enough to have babies'.
These are the pressures that are going to have a species develop claws, run faster etc.
2. Sexual selection.
That is, even if a specimen is surviving and reproducing, within the species certain traits might be being selected for and in the long run a species ...
21
Strong Emphasis on Long Term Reward
The purpose of fear is a prescriptive measure in humans to have them avoid getting into bad scenarios which have short term gain. Should primal man venture into the night? Fear says no, because you'll get eaten by wolves. Should modern man rob a bank? Fear says no, because you'll get caught and have to go to prison. In ...
18
Whenever one of these base emotion questions come up, I like to bring up Lövheim's Cube of Emotion
Now I have to put a disclaimer here, before I go any further. The connection between monoamine neurotransmitters and the eight "basic" emotions that Lövheim proposed deserves some skepticism. He proposed it in 2012, and very little follow up has been done. ...
17
Mike Scott observed that the necessary conditions already prevailed on earth, so I will throw out some ideas on why they might have stayed that way.
High Gravity
Anything which hinders locomotion would select against animals. A high gravity planet could make the cost of locomotion higher than the benefit. There is some question about plant propagation ...
11
Maybe, but not directly because of nutrition. I think the other answers give good animal examples of very intelligent carnivores and herbivores. As for people, I have some coworkers who are strict vegans, others who have been on a strict keto diet for years. Both groups are healthy and very intelligent people. I think we all agree that omnivorous diets ...
11
Jungle Giving Way to Savanna
Your orcs share many similarities to humans in that they are both bipedal, roughly the same size and have evolved very high intelligence (for the animal kingdom). So therefore the pressures that made humans will therefore be similar to the ones that made orcs, as this is how convergent evolution works.
The Orcs ancestors were ...
11
A slow heart rate plays a major role in life expectancy for example,
The smallest known mammal the Etruscan shrew has a heart rate of 1,500 BPM and a lifespan of 2 years.
The largest land mammal Elephants have a heart rate of 30 BPM and a lifespan of 80 years
Tortoise have a heart rate of 10 BPM and a lifespan of 180 years
Bowhead Whales have a heart ...
11
Camouflage!
Your answer already exists on the SLOTH!
"It is a popular assumption that algae in particular form a symbiotic relationship with the sloth, obtaining shelter and a good supply of water as sloth fur absorbs water extremely readily, and providing in return camouflage and extra nutrients via diffusion and absorption through the hair and skin."
...
11
Terraformed world.
A world which had been seeded with only plants could meet your criteria. Imagine a world like the ancient earth, but empty of life. Terraformers seed its oceans and land with bacteria, wind-pollinated plants and photosynthetic organisms. Perhaps they add some fungi to help break down dead material.
Animals might eventually evolve from ...
9
First I want to point out that we see on earth a large diversity in limb length, but almost no diversity in number and arrangement of limbs. It seems that evolutionary forces can change limb length very easily even when other things are very hard. If most of the mega fauna have a similar proportions of limbs, then you would suspect convergent evolution ...
9
Other answers have done a great job explaining that this could indeed be very possible. I would like to point out a couple of things to consider about a world that has evolved with only plant life:
No food plants
"Edible" plants like fruits, vegetables, nuts, and nutritional root plants have evolved mainly to spread the seeds of the parent plants through ...
8
(1a) Pansermia is possible and arguably likely
What you're looking for is a specific type of panspermia called lithopanspermia - the transportation of organisms embedded in rock between worlds. The benefit of putting organisms inside rock (as opposed to clinging to the outside) is that they can lie dormant for thousands of years, unaffected by radiation. ...
7
The factor you're looking for isn't time. That sounds funny, doesn't it? But it's true. You're looking for a divergence in the human gene pool to the point where it would be incapable of reproducing with the previous point. And to that end, time is one factor among many, and not even the most important one. There are species on this planet which have ...
7
Yes. An awful lot of evolution is possible in 100 million years.
Consider your question in the context of it being asked slightly differently by an intelligent alien visiting Earth 100 million years ago. At that time there existed a family of small, unintelligent, timid pre-rodents called multituberculata, the last common ancestor of mice and humans. Your ...
7
No.
As evidenced from the fact that a good number of humans are perfectly fine being vegetarian, it's entirely possible to get all the necessary nutrients from vegetation for intelligent thought. I've seen a few theories that toss around the idea that only an omnivorous species would be capable of advancing towards intelligent thought because of the ...
7
Do Drepanosaurs count?
Drepanosaurs might be described as bird-monkey-chameleon-things, or monkey-lizard if you're in a hurry. They were arborial reptiles during the Triassic, characterized by bird-like facial features, primate-like prehensile tails and grasping appendages, chameleon-like skeletal structure, and sometimes a tail-claw.
Adjust the diet a bit ...
7
Humans aren't patient enough for evolution, so we've just gone ahead and done it already. The spider silk gene has already been spliced into goats, which then produce the spider silk protein in their milk. There is ongoing research to splice this gene into plants which could then be harvested for spider silk. So overall, it's absolutely possible for other ...
7
There is no evolutionary pressure I know of that will do this
You have two impossible conditions (technically three including the optional one, but it's optional). These are 'bipedal, with wings' and 'looks surprisingly humanoid'. A creature the size of 11 inches would have no reason to look humanoid - in fact, it would have several reasons not to. This is ...
7
They could have evolved white fur coat if they had moved to a snowy climate, as to blend in with the snow.
They also might evolve hooves because, like horses, having just one toe reduced the weight they had to carry at the end of each leg, making it easier for them to run and maneuver.
Evolving similarly to mountain goats could produce some cool traits.
-...
6
Nope, many species show otherwise
There are a number of species out there which are probably sapient or close to it, and which exhibit a wide range of dietary habits.
Carnivorous - Odontocete cetaceans (particularly dolphins) are highly intelligent and exclusively carnivorous. Notable orcas (Orcinus orca) are Tyrannosaurus rex-sized apex carnivores and ...
6
The distinction between carnivore, herbivore and omnivore is not that strict. It's more about "default" behavior, than about ability/inability to consume different kind of food.
For example a lot of dogs - obligate carnivores are being fed with pasta and/or porridge. It is not good for their health, for sure, but dogs are still able to live and breed on ...
6
At least one source suggests that having children later in life helps promote longer lifespans for women.
This could mean that being more selective about children will result in a lengthening lifespan, and could also contribute to the aspects of elves from some fantasies eventually being in decline, population wise.
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