We all know what the minotaur is and what it looks like, a buff man with the head and tail of a bull. But could this creature evolve? Could it even exist? If a Minotaur could exist, what environmental pressure would lead to its evolution?
A list of all of the Anatomically Correct questions can be found here
Could this Creature Evolve?
The short answer is no.
One point is the head size and shape. Given the size of the average female vagina, I'm going to say that minotaurs would either need to be birthed extremely early in their development (which would cause a host of other issues) or delivered entirely through cesarian (which is not an evolvable trait) without other significant physical changes not noted in common minotaur lore.
Another point would be to look at the nose. Bulls have very large nostrils because they need to fill large lungs. Filling a human's lung with nostrils that size would actually be quite hard due to the notable increase in length that the air would need to be pushed/pulled from. It's not impossible, but it would be a huge waste of energy that evolution would shy away from. I can't even begin to think of what benefit a creature would obtain from having to work hard to breathe.
I could go on, but I think I've already shown there's no sane evolutionary path that would lead to a minotaur.
Could the creature Exist?
This is actually a different question than above. Assuming advanced genetic engineering (far beyond what we have today) and no care about the cognitive/motor capabilities of the result, sure. Why not.
What Environmental Pressure Would Lead to Its Evolution?
The best and only pressure I can think of would be sexual preference. Early people simply preferred mates that had more bovine facial features but still human bodies. An odd fetish, but that's really their private business.
Note that you would have to start with a very large stock of humans, who would have to all spontaneously develop this sexual preference. The reason is, again, that the birthing issue is just so non-trivial. The infant and maternal mortality rate would be extraordinary.
I would assume that if Minotaur were to evolve, they would neither evolve from humans or bulls. I would say that a Minotaur is probably an ape, most likely from chimpanzee origin, possibly from apes that left the jungle for the plains. The "simian ridge" seen on a chimp's skull could become a bone basis for the horns, with the some hair becoming a keratin outline, extending the horns. The long face would have to flatten out a bit to become more bullike, or perhaps remaining semi-apelike, either one could work in my opinion, but judging that these beasts would need to be around for humans to see, I would go with the latter option. They would most likely become larger creatures, using their size and horns to intimidate smaller creatures away from kills, making intimidation a main tactic for food, and giving rise to them being scavengers. Perhaps tool use could evolve for them sometime down the line.
I'm pretty sure the only answer to anything natural arriving at this is no.
if a minotaur is a cow that evolved a human body
A cow's body is rather well designed to its grass eating task. It has several stomachs to breakdown this relatively tough to digest food and includes a re-chewing process (known as ruminant digestive system). First stomach is basically a storage site as they quick eat grass without chewing sufficiently. Then ruminate (chew their cud) somewhere in the range of 40k chews per day. There is also a fermentation phase involved...somewhere near 75% of the cows abdomen is space reserved for this digestive process (it's a 40 gallon system in a full grown cow).
So the answer here is a giant no...the human form cannot support the full digestive system required to feed on grass.
if a minotaur is a human that evolved a bull head, it eats what humans eat.
A bull's head is actually quite a piece of artwork...the large head protects the neck while charging and supports the muscle structure required to take these impacts. A human neck is really incapable of all of this. I'm actually having problems picking out what benefits a bull head would grant that wouldn't be a giant negative in some other attribute. Perhaps the 'Loki' discussion goes in here...his superpower must include super human neck strength to support those silly horns on his helmet after all.
There is also the birthing issue if this coming from the human side. A Minotaur head is huge compared to the human counterpart...how exactly a baby Minotaur could get out is beyond me.
I'd go as far to say it's not really feasible in the genetic engineering domain either...I mean perhaps as a single 'Frankenstein' creation, sure...but it wouldn't be a stable creature capable of procreating or competing in most environments.
I think the best way to justify the evolution of a minotaur is to remove the 'human' element entirely.
Rather it is a bovine species which has evolved to become bipedal and developed articulated 'hands' and opposable thumbs. Which then of course gives them a 'humanoid' likeness.
Maybe environmental pressures lead them to become carnivorous which subsequently leads to very diverse evolutionary opportunities.
How they get there is a little beyond me...
... as far as I'm aware the origin of our hands is from digging; then climbing; then finally using tools (swimming might be in there somewhere too).
After hands we then started to 'stand up' - I guess as our front limbs became less useful for walking on. This then opened up the advantages of being bipedal for a number of things: mainly steady, long distance running.
I want to offer a contrary opinion to the question "Could such a creature evolve?", and argue, yes, minotaurs could evolve.
Before starting, it is worth noting that the minotaur of greek mythology (i.e. THE minotaur) was a singular individual created by divine intervention; if we want to consider the possibility of minotaur evolution, we need to allow for the existence of a population of minotaurs, more like the minotaurs that populate fantasy RPGs, C.S. Lewis's Narnia etc.
The key element in understanding how a human or human-like ancestor could give rise to a population of minotaurs is to recognise (assume) that typically minotaur traits are secondary sexual characteristics that emerge largely after puberty under the influence of a testosterone surge. (This limits the typical minotaur appearance to males; females would be substantially less "minotaur-like", and we expect/predict a substantial amount of sexual dimorphism, perhaps of a similar degree to that seen in gorillas where adult males can approach twice the body mass of adult females). This should get around any obstetric complications associated with a human-like mother giving birth to a horned bull-like head!
Evolutionary Scenario:
Imagine a pre-minotaur population where physical strength is important for male reproductive success. This may be because the environment poses particular challenges; because of violent confrontations between males of different groups (as in real-world chimpanzees); of perhaps because males' access to potential mates is mediately largely by competition between males - bigger, stronger males outcompete the smaller weaker ones, and father more (most) of the babies. This is seen in multiple real-world non-human primate species, so is not unreasonable.
Imagine a male is born with a genetic mutation that has two effects: distortion of the skull (a hint of a bovine appearance), and increased responsiveness to testosterone at puberty, such that post-puberty this male is larger and stronger than other males. This will result in increased mating share, with his offspring inheriting these proto-minotaur traits. If we wanted to we, could also imagine that testosterone at puberty also exaggerates the bovine-like features of the skull; regardless, it may well also increase the aggressiveness of these males.
Over time, the population would come be dominated by individuals (males) who have this proto-minotaur phenotype.
Now imagine also that a genetic trait exists that is expressed in females that relates to mate-preference. Given opportunity to exercise choice (which might be just a matter of being more or less resistant to male mating approaches), females "prefer" (i.e. are more likely to mate with) more physically-powerful males.
Particularly if the increased aggressiveness between proto-minotaur males led to a population structured into small groups, females might be able to skip out of one group and join another - not that different to the situation that seen in modern gorillas, where females choose which harem to join - and this leads (at least in this scenario) to inter-sexual selection that, over generations, exaggerates the proto-minotaur traits into full-blown minotaur. Horns, for example, extending and developing from initial small bony spurs of the semi-bovine skull, perhaps even acting as honest signals of the male's genetic quality even though they are exaggerated beyond useful, head-butting size/shape.
For females on the other hand, we would not expect a significant increase in body mass over the ancestral population (perhaps a little, as it might be dragged upward by selection on male body mass), and the bovine-like features would not be as strongly exaggerated, but they would be noticeably not human. Female minotaurs should be smaller, less aggressive, and less bull-like.
Social structure might mirror that seen in gorillas, with males holding harems, dispersing at puberty and spending time alone before assembling their own harems, but the need to hunt for meat - we're still assuming these minotaurs are (at least part-time) carnivores - would probably require cooperation between males to bring down large prey, so perhaps harems nested in a more chimpanzee-like community structure might work? (incidentally, this is what Edgar Rice Burroughs came up with for his fictional apes in Tarzan, but I didn't recall that until I got to this point in the argument). Note that this line of evolution would equip minotaurs with primate-like teeth, allowing for the exaggerated canines seen in much of the artwork, rather than the typical bovine dentition more suitable for eating grass.
So an evolutionary argument can be mounted for minotaurs, that avoids both Goldschmidt's 'hopeful monster' speculation, and particularly unusual birth complications.
This is actually not too difficult anatomically. Large herbivorous primates already exist (gorilla) and have existed (gigantopithecus). to the digestive anatomy is easy, a bovine head is not too difficult although you have to reopen the eye socket, apes have solid eye sockets which will not work with a bovine head. Of course they will not have human like intelligence or brain size, something more like an australopithecine will be more likely, basic tool use but not very creative. Supporting a human brain on an herbivorous diet is difficult and there is only so big you can make a head and still give birth to it.
the real trick is the horns. These will be tricky to evolve but not impossible horns have evolved multiple times. Horn are just a sexual characteristic tails could be as well, Horns however will require a serous change in the anatomy of the head as they grow up to support them, this however is seen is other animals so it's not impossible.
So the evolutionary pressures are herbivory and sexual selection, but the real issue is time this line needs to split off the primate early to have enough time to alter the skull this much which means they are going to have to evolve naked skin and upright posture independently or alternatively they can split off the hominid line but the story needs to be set far far in future.
