“They seemed mostly head, with little scrawny bodies, long necks and six legs, or, as I afterward learned, two legs and two arms, with an intermediary pair of limbs which could be used at will either as arms or legs. Their eyes were set at the extreme sides of their heads a trifle above the center and protruded in such a manner that they could be directed either forward or back and also independently of each other, thus permitting this queer animal to look in any direction, or in two directions at once, without the necessity of turning the head.   The ears, which were slightly above the eyes and closer together, were small, cup-shaped antennae, protruding not more than an inch on these young specimens. Their noses were but longitudinal slits in the center of their faces, midway between their mouths and ears.   There was no hair on their bodies, which were of a very light yellowish-green color. In the adults, as I was to learn quite soon, this color deepens to an olive green and is darker in the male than in the female. Further, the heads of the adults are not so out of proportion to their bodies as in the case of the young.    The iris of the eyes is blood red, as in Albinos, while the pupil is dark. The eyeball itself is very white, as are the teeth. These latter add a most ferocious appearance to an otherwise fearsome and terrible countenance, as the lower tusks curve upward to sharp points which end about where the eyes of earthly human beings are located. The whiteness of the teeth is not that of ivory, but of the snowiest and most gleaming of china. Against the dark background of their olive skins their tusks stand out in a most striking manner, making these weapons present a singularly formidable appearance.”

This is our first description of the fabled Green Man of Mars, from Chapter Three of Princess of Mars, when John Carter looks within an incubator and sees the infant Green Martians.   A face only a mother could love, if they had mothers.

Beyond that, we learn that the Green Men stand ten to fifteen feet tall.  They weigh up around 400 pounds, which would make them about 1000 pounds on Earth.   They’re muscled in proportion to their gravity, which suggests that they’re skinny and slender, almost stick men.   They are strange and ferocious creatures, perhaps the first true aliens in science fiction.

Now, its true that H.G.Wells tentacled Martians preceded the Green Men by a good decade, as did George Griffiths angelic Venusians.  But I would argue that with the Green Men, Burroughs did something groundbreaking.

Wells' Martians were alien yes, physically alien and intellectually inscrutable.  But we never learn much about Wells' aliens, who they are or how they think.   At best, Wells' aliens are just an intellectual exercise, Man taken to ultimate evolution, reduced to a brain and hands.

Burroughs' Green Men, on the other hand, were honest to god living creatures.   John Carter sees them in their own environment, he observes their lifestyle, their habits and politics, the way they think.   As an observer among them, we get our first honest to god picture of aliens being alien, rather than paper cutouts.   We see literally every aspect of Green Martian life, from their incubators, eggs and child-rearing, to their war making, from the relations between the sexes to the economics of their tribes.   And by and large, its not judgmental.

Of course, there is harsh criticism of aspects of Green Man society.  But this is interesting, it doesn’t come from John Carter or even Dejah Thoris.   The fiercest criticisms of the Green Men and their lives come from Green Men themselves.   It’s a remarkable effect, suggesting that the Green Men are both larger and deeper than the society we see.  It does not allow them to be stereotyped.

Given the casual racism and the almost naive society in which Burroughs lived, the Green Men are a remarkable accomplishment, building aliens who are genuinely alien, without ever really passing judgment on them.

Of course, one could argue that the Green Men are not that remarkable.   In their nomadic lifestyle and harsh and stoic qualities, Burroughs was undoubtedly taking a leaf from descriptions (accurate or not) of ‘savage’ Indian tribes like the Comanches, Apache and Ojibway.   This isn’t much of a leap, the Princess of Mars starts out as a western in its first two chapters after all.

But nevertheless, there is a skilled and quite vivid depiction, not just of an alien creature, but an alien society.

The creatures that John Carter encounters, of course, are Tharks, so named for the dead city in which they periodically gather.   There are other tribes, the North and South Warhoon, the Thurds and the Torquaas are mentioned as well.

The Green Men are nomads, riding thoats and herding zitidars across the vast dead sea bottoms and desert regions of Mars.   They travel in relatively small bands of a few dozen or hundred individuals, both male and female.   These bands from time to time congregate into vast tribal gatherings in dead cities, before once again dispersing.   Females do much of the work, males make most of of the war.  They’re organized loosely into a feudal hierarchy, but rank is established by trial by combat.

And here are their cousins, the Great White Apes:

"A colossal ape like creature, white and hairless except for an enormous shock of bristly hair upon its head....    The thing, which more nearly resembled our earthly men, than the Martians I had seen.... The creatures were ten or fifteen feet tall, standing erect, and had, like the green Martians an intermediary set of arms or legs, midway between their upper and lower limbs.  Their eyes were close together and non-protruding, their ears were high set, but more laterally located than the ears of Martians, while their snouts and teeth were strikingly like those of our African gorilla."

With respect to the Great White Apes, we have fundamentally far less difference from the Green Men than we have between Humans and Apes.   So far as we can tell from the descriptions, the White Apes have fundamentally the same physical proportions and dimensions as the Green Men, with respect to legs, arms, middle arms and torso.   Their Six limbs, and ten to fifteen feet in height, are identical to the Green Martians.   Only their white colouration, and their apelike features distinguish them from the Green Martians.

Taxonomically, its very tempting to assign both the White Apes and Green Men to the same species, or at the very least, we must conclude that they are extremely closely related species. 

Indeed, they are so close that one is tempted to wonder whether the Great White Apes of Mars were Burroughs original template, a kind of ‘first draft’ for his alien race, which he was loath to throw away entirely.   The relative normality of its features might suggest Burroughs leafing through books of animals, trying to imagine a face both human and alien.

Or perhaps they followed the Green Men, building on a kind of notion of the same affinity to the Green Men as humans have to gorillas.   The depictions of the ape frequently invoke the simian nature of the creatures, and like the gorilla, it is far stronger than its civilized relative.

Or, if we want to speculate wildly, we might notice that the Green Men were at least partially inspired by native Americans, returned to a ‘healthy’ traditional nomadic lifestyle.   The White Apes, on the other hand, seem remarkably caucasian.   Twice in two paragraphs, John Carter comments that their appearance is more human than the Martians.   Perhaps Burroughs had in mind a ‘morlock’, and the White Apes were symbolic analogues of white men, bestial ruthless city dwelling creatures.   Traces of this sort of thinking are all over the Tarzan books, where Burroughs often finds the urban white men, be they European adventurers or denizens of lost cities like Opar to be degenerates compared to his jungle prince, Lord Greystoke.

The Great White Apes are intriguingly mysterious.   No surprise there, of course.  Burroughs never bothers to get into the details of Banth home life, or the habits of Calots, and can’t even be bothered to describe a Zitidar in detail.  Clearly, explicit depictions of the flora and fauna were often limited to their ability to pose danger or offer succor to the protagonists.   John Carter is a fighting man, dammit, not a naturalist.

Despite this, the Great White Ape clearly is not an ordinary animal.  Burroughs returns to the creature again and again, adding more tantalizing details each time. 

In John Carter’s first encounter with them, on A Princess of Mars, he meets a pair, apparently mated.   They carry stone cudgels, and appear to speak, gesticulating and gibbering.    This is interesting.   Clearly, they are habitual tool users, rather than opportunistic ones.  Both of the apes are armed, and these are weapons that they must be carrying with them.  Their gestures and gibbering is suggestive of a language.   They appear to be associating in pair bonds, an alien thing for the Green Men.   In short, what we have here is not truly an ape, but perhaps something closer to a cave man.

Great White Apes reappear in The Gods of Mars, running about in numbers in the Valley Dor.   They do not attack, and are not attacked by the Plant Men, and they seem to have a fair population.  They are part of the Therns cult of Iss, one of the original beings, and the repository of reincarnated souls of the devout.   This tells us more about the Barsoomians, and particularly the Therns perceptions of the White Apes, than it does about the Apes themselves.

They also appear in Thuvia Maid of Mars, when Carthoris is captured by a band of the creatures.  These Great White Apes wear clothing or harnesses of thoat hide, they have a large social group, they take prisoners, engage in communal activities, wield weapons and seem to have a language unintelligible to the red Martians.

Great White Apes are the subjects of Ras Thavas experiments in Master Mind of Mars.   In fact, half a human brain is transplanted into a White Ape, and half a White Ape brain is tranplanted into a human.   Oddly, they do not get together for a wacky sitcom. 

The man with the white ape graft turns out to be beastial, gibbering in a manner that cannot be understood,   walking on knuckles, showing animal-like reactions of hostility and fear.   His motivations are primitive, his impulses are acted upon immediately.   Seeing a corpse, he announces that he is hungry and will eat.  With the human graft to the White Ape body, Burroughs lets slip that the White Ape is habitually bipedal.   It goes on two legs more often than four.   Their animalistic vocal cords are not consistent with speech.  Later on in the book, we learn that some White Apes have been domesticated as performing animals, and have remarkable abilities.

They appear in A Fighting Man of Mars to give Tan Hadron a hard time in a deserted city.   Hadron notes that they are both intelligent, ferocious and relentless   And of course, there’s a final appearance of an army of Great White Apes with transplanted human brains in the Giant of Mars.

The White Ape in the wild is  a near mythical creature.   It is the only type of being that the Green Men themselves fear.  Indomitable in war, relentless against their enemies, equally contemptuous of Banths or Red Men, the White Ape terrifies them.   Even John Carter admits that they creep him out.

Nevertheless, the cumulative picture of them is of a creature which is far closer to human than animal, far more likely to be a sentient being in its own right, than a simple monster. 

They appear to have a language, though it is not mainstream Barsoomian.   John Carter’s first encounter with them in Princess of Mars refers to ‘gibbering’ which suggests some form of unknown language.  Further, Carthoris’ encounter with Great White Apes reinforces the conclusion that there is a language in play, he encounters Great White Apes who wear clothes, use tools and gather socially.

The White Apes recurring tool users.   John Carter’s first encounter with them is an apparently mated pair who carry stone clubs.   Carthoris also reports clubs, wearing of hides, use of rope and bindings, and social behaviour in aggregations of fifty or more, part of that social behaviour was postponing immediate gratification by eating Carthoris instantly, and intending to kill him, either as part of a ritual, or for communal sharing.

Vad Varo's (Ulysses Paxton) information is tainted, given that he is working with Men and White Apes who have had partial brain transplants.   The human influenced by a white ape brain is feral and impulsive.   The ape influenced by a human brain is clever.  The ape (man) can speak, though its vocal chords either naturally or through disuse, are not well adapted for human speech.  Obviously, the cranial capacity of the ape matches that of a human brain.  Paxton’s allies report that trained apes are capable of remarkable feats ‘within their limits.’

So the question emerges, what are the actual capacities of these creatures?.   It should be noted that there may be an implicit racism at work.  Both the Red Men and Green Men, despite evidence of White Ape tool use and language, clearly see them as animals.   This may in part be derived from a failure to speak the common language, and a well known ferocious and predatory disposition.  The Green Men are noted as hunting them for sport occasionally. 

The Red Men have occasionally trained some as performers.   It may well be that the perceptions and preconceptions of Red and Green Men actually underestimate the White Apes abilities.   It is, for instance, possible that the White Apes may have intellectual and behavioural abilities on a par with Red and Green Men.

Of course, the tool use that we observe seems to be a fairly rough and primitive kit, consisting of stone age tools and weapons, found artifacts and limited manufacturing.  There is no record of a natural White Ape operating a flyer or handling a radium rifle.   Is this an innate limit to the creatures?   Are there levels of complexity they simply cannot master?  Or perhaps its some other innate flaw, perhaps a defect of hand/eye coordination, a failure of vision, an neural wiring handicap that leaves them unable to conceive of long distance effects, an attention deficit disorder type learning disability, a memory issue?   Or is this a combination of a cultural defect and lack of opportunities?   It’s not at all clear.

The safest conclusion might be to say that while the Great White Apes potentials are not fully determined, and may be equivalent to the Green Men, but that their demonstrated abilities fall rather far short of this.

On the other hand, in terms of tool use, clothing, social behaviour and evidence of planning, the Great White Apes are far ahead of conventional terrestrial apes.   They are most closely on a par, perhaps, with prior hominid species, such as Homo Erectus or even Homo Sapiens Neandertal, or even possibly with some cultures of Homo Sapiens Sapiens, such as the Yanomano of South America or the Tasmanians.   Essentially, they seem to be a semi-nomadic, xenophobic, stone age culture.

In broad terms, whether the Great White Apes are actually at human levels, or near human levels, the distinctions may be arbitrary.  Either way, there is a far, far greater gulf between them and animal levels of existence which justifies us placing them within the same family or category as the Green Men.

So, what are the big distinguishing features between Green Men and White Apes? 

Primarily cosmetic its mostly cosmetic.  Although generally the same size, the White Apes are reputed to be significantly stronger and more ferocious than the Green Men, although the parameters of this are not at all clear.

Apart from that, the White Apes have white skin and shocks of dark hair or manes on their heads.  The Green Men are green skinned and hairless.

After that, all the apparent differences are in the head, and here I’m referring to physical properties rather than cognition.    Green Men and White Apes have heads of roughly the same size and shape, but the appearance is radically different. 

Green Men have relatively large to medium sized eyes set widely apart and protruding, capable of independent movement.  They also possess independently mobile ears on stalks at the top of their head.  Nostrils are small and not prominent, meanwhile, both males and females possess massive tusks protruding upwards several inches from their lower jaws.

In contrast, White Apes eyes are set close together and recessed.  They have small ears on opposite sides of their heads, prominent flat nostrils.  Their teeth are similar to a gorillas, so they have pronounced canines, but these fall far short of tusks.  They possess heavy jaws and sagital crests.  Overall, the face resembles that of a gorilla.

In short, these two faces are as different as night and day, its amazing to think that they might belong on two closely related species.    But the reality is that these faces reflect adaptations to very different environments.

Consider the environment and lifestyle of the Green Men.   They are equestrian nomads operating out in the open in desert and plains environments.   In their normal habitats, there aren’t a lot of obstacles or complex geography.  Instead, the landscape opens up around them in all directions, with just enough roll and slope, enough bushes,  to allow an enemy to sneak up.

Hence, widely set eyes, which maximize peripheral vision.  We see the same sort of thing with other plains/open country animals like horses, buffalo, antelope, etc.   It becomes an evolutionary advantage, in open country, to have as wide a view of that countryside as possible.  Burroughs was probably well aware of the reasons natural selection would aim for widely set eyes.  In fact, he goes it one better by allowing the eyes to look in different directions simultaneously, a notion he undoubtedly got from chameleons.  The independently mobile ears mounted on stalks serve the same function, allowing the creature to scan and focus in all directions, including directions independent of the head or the eyes.   Hence, a Green Man’s sensory apparatus is, in general terms, continually sweeping through a large volume of its environment.

Of course, if you have to see accurately out to the horizon, you will tend to develop visual acuity and larger eyes results.   Green Men can also focus their two eyes together for binocular vision, and actually have extremely good eyesight and depth perception.   John Carter sees this himself when his tribe of Tharks essentially shoots to pieces a Red man warship.   Although more heavily armed and armoured, the defenders in the cruiser simply cannot match the accuracy of the Green Men.   This implies that Green Man vision sees farther, sees in more detail and has a higher ratio of depth perception than Red Men.  They’re the ‘eagle eyes’ of the Martian world.  It’s just a guess, but their night vision may be pretty good too.

In the Green Man environment, one sense that probably is less reliable is scent.   The Green Men do not move with their faces to the ground.  Rather, they’re ten to fifteen feet high, which means that you’re going to be remote from local odours.  And as riders on Tharks and Zitidars, they may travel frequently at heights of twenty to thirty feet.   So, as with humans, scent becomes a declining sense.   Their noses are reduced.

The one big anomaly of Green Men is their dramatic tusks.  These tusks are not a sexual characteristic, they’re seen with both males and females, and even with juveniles.   At first glance, it is hard to imagine them as a significant natural primary weapon.   In order to use them in combat or attack, the Green Man’s jaw has to distend or dislocate.   All the pressure winds up coming to bear on a flexible jaw hinge.  Consequently, if a Green Man sinks his tusks into an enemy’s soft body parts and there is any kind of sideways or sheer pressure, he’s likely to break his jaw at the hinges. 

Alternately, if a Green Man tries to gore and strikes bone or armour, the shock of impact gets absorbed by his jaw and the attack fails.   Of course, that’s not necessarily a bad idea.  Saber toothed tigers were very liable to shatter their teeth is they happened to bite into the bone.  So this arrangement may actually protect Green Man tusks from shattering by transferring shock away.

At the same time, however, it substantially reduces the power available to a Green Man for his tusks.   A Saber Toothed Tiger used its saber teeth for a killing stab.   Mounting its saber teeth in the upper jaw, it was able to use the heavy musculature of its neck and shoulders to deliver a powerful downward killing strike. 

For a Green Man, however, the musculature available for a killing strike is the jaw muscles pulling upwards.   These may be powerful, but there’s only a fraction of the muscle mass available in a Saber Toothed Tigers neck. 

Moreover, a saber tooth tiger can use the muscles of its back and forelimbs as levers, amplifying the power of its strike.  However, a Green Man’s muscle arrangement won’t work that way.   If a Green Man tried to put his back and arms into an attack, this would only add a little to the power of the tusk strike.  Moreover, it could work against the strike, if the jaw muscles weren’t powerful enough, using the body to drive a strike would force the jaws further open.   The arch of forces are going in the wrong direction.   So, even if they’re putting their body into it, the muscles of the body are driving in the opposite direction of the jaw muscles, and the overall result is weaker.

Given this, I suspect that Green Men seldom suffered shattered tusks in the way that saber tooths did.   Their bodies motion dynamics would tend to work against that.   At the same time, their tusk strikes would be quite weak compared to the big cats. 

But then again, how strong would they have to be if your intent is to plunge them into soft vulnerable tissue?   Indeed, if you are using your body for the power of the strike, your jaw muscles might be comparatively weak, what you would want in there would be a certain degree of flexibility and cushioning in the jaw joint, particularly against sideways shear force (the big danger), and you would want tendons and ligaments, even cartilage from hell.   The idea here is that you don’t necessarily need a lot of muscle, if all your striking power is in the body itself, but you would need very strong tendons and cartilage to make sure you don’t simply tear your jaw out.    The power of the strike comes from the body, the jaw attachments are shock absorbers making sure the tusks don’t shatter.   In a way, it may even be a more efficient design than saber tooth tigers.

It’s certainly used to substantial effectiveness, as John Carter witnesses:

“Bar Comas had much the better of the battle as he was stronger, quicker and more intelligent. It soon seemed that the encounter was done saving only the final death thrust when Bar Comas slipped in breaking away from a clinch. It was the one little opening that Dak Kova needed, and hurling himself at the body of his adversary he buried his single mighty tusk in Bar Comas' groin and with a last powerful effort ripped the young jeddak wide open the full length of his body, the great tusk finally wedging in the bones of Bar Comas' jaw. Victor and vanquished rolled limp and lifeless upon the moss, a huge mass of torn and bloody flesh.”

This analysis gives us something of a window into the early Green Man evolution and lifestyle.   Literally, they’re the saber toothed tigers of Mars.   They are essentially big game predators, and their hunting style was likely similar to the saber tooth cats.   Essentially, ambush, grab the prey and then kill by sinking the tusks into soft tissues of the neck or abdomen.

Thats a little gross, I admit.  But mammalian predators are nasty.   Regular big cats have comparatively weak jaws (compared to sharks or dinosaurs), and they kill, literally by choking prey to death or opening up arteries.   Cheetahs kill by figuratively tripping their prey.   Wolves slowly disembowel their prey and wait for them to die of the wounds.  Sometimes, in the case of wolves, the prey isn’t quite dead before they settle down to eat.   The reality is that killing is hard work, and evolution always looks for an easy way to accomplish that task.

Green Man adaptations as open country big game hunters, suggest that they were roving predators, attaching themselves to and hunting in large herbivore herds.   A big game kill could feed several individuals, so it made sense to hunt as packs or social predators like lions and wolves.   So clearly, they became open country dwellers with social structures, much like the various animals they hunted. 

From there, they undoubtedly made the transition to animal domestication.   This isn’t necessarily as hard as it sounds.   In the wild lands of North America, wolves may run about very close to a herd of caribou without unduly spooking the whole heard.   In Africa, lions may lounge about with zebra and antelope unconcerned only a few hundred yards away.   Generally, in these situations, the strong and healthy members of the prey species count on the fact that with a head start of ten or twenty yards, they can outrun or outfight their predators.  For their part, predators will tend to look for the weak and vulnerable members of the herd and leave the strong ones alone.   As for herbivores, in Africa, we can see many breeds of herbivores mixing.  Herds can include elephants, giraffes, zebras, antelope of various sorts and rhinos, all more or less tolerating each others company.     So, by analogy, the Green Men were probably social predators around large herds made up of multiple species, some of which were more likely to be prey than others.

The theory on human domestication of wild animals like horses, cows, sheep, goats and water buffalo is that these particular herd animals had a social structure that humans could insert their own social structure into.  Thus, the domesticated animals had a kind of innate tolerance and a way of behaving with each other that humans could take advantage of.  Other wild animals, with slightly different social structures could not be domesticated.   Thus, Europeans and Asians could domesticate the Horse and Cow, but Native Americans were unable to domesticate the Moose and Bison.

Learning to ride Thoats and Zitidars probably made it a lot easier to keep up with the herds and to hunt more effectively.   This implies that the preferred hunting species were probably animals other than Thoats and Zitidars.   It is likely that the Green Man contribution to early Barsoomian civilization was the domestication of animals.

That is no minor accomplishment.  Without machines and without animals, the only source of power for building or agriculture was human labour.   A man working alone or with other men, can plow only a fraction of the land that a horse team can.  Thus, animal power greatly expands the amount of land that can be tilled with agriculture, which expands the amount of agricultural produce available, and expands the amount of population it can support.  Herd animals can carry far more weight than humans and carry it much further.   Mounted warriors can devastate their footsoldier enemies.    The domestication of big animals on Earth was literally the first great industrial revolution in human society, as big or bigger an accomplishment as agriculture itself.

Now, let’s turn to the White Apes.   Their eyes are smaller, recessed and close set.  What does this tell us?   A lot less peripheral vision, and a lot better binocular vision.   (Binocular vision is where the eyes are looking in the same direction, allowing them to judge depth)  The fact that peripheral vision is less necessary, while binocular vision is mandatory, tells us something about the environment of the White Apes.   Let’s put it this way, they weren’t ‘open country’ creatures.  On Earth, there are two main groups of creatures which emphasize binocular vision:   Predators - dogs, cats, lions, tigers, etc., and tree dwellers - monkeys, apes, raccoons, etc. 

Why is this?   Because binocular vision is critical for judging distances.   Imagine you are a monkey, you’re dancing around doing monkey things.  You leap for another branch....  Which turns out to be six inches further away than you thought...   Now, for a ground creature, you just try again.   If you’re that monkey, you’re going to drop 150 feet and break a few bones and even if you survive, you may be too badly injured to escape a predator.   So, the bottom line, if you are hanging around in an environment where having an accurate idea of just how far away everything around you is, you’d better get binocular vision.   The same, with slightly less urgency, holds true for predators.   If they’re leaping in ambush, a few inches either way may mean the difference between steak dinner and a mouthful of fur.   So, the bottom line is that you move the eyes away from the sides of the head, and get them facing front.

Of course, here’s the thing though.   If you are in an environment that is really complicated, like trees or bushes or a dead city, its important to judge the distances of things in your immediate vicinity.  That’s only common sense.  But it also means that your view is obstructed.  Out on the open country, you can see to the end of the horizon.  In your jungle or dead city or complicated environment, what you see past the trees and bush or ruins around you is more trees, bush or ruins, and past that, more of same.   Basically, you’ve got all this stuff obstructing your view.

One consequence?   Well, you don’t need excellent peripheral vision as much, because you know that the other creatures in your environment are also having their view obstructed.   So you don’t need to have to see in all directions, cause they can’t either.   The other thing is, you don’t have to see over large distances...  Because you can’t.  There’s all that stuff in the way.   So your long distance vision is a lot less.   Instead, your eyes shift to looking very carefully at your immediate vicinity.   The result, of course, is that your eyes move closer together to focus, they get smaller, and your gaze gets more precise.   If you need to look around, then just turn your head a lot.

The same thing happens with ears.  Suddenly, its not so important to pick up all sounds, which you would do with independently mobile high mounted ears.   It’s a lot more important to precisely know the direction of the sounds you do hear, particularly because you may not be able to see something.

Now, a lot of animals have independent swivelling ears at the tops of their heads on Earth.  Humans have small ears on the sides of our heads, as do a handful of other animals including elephants.  What’s going on?    Well, it turns out that setting the ears on either side of the head, with a big mass of bone and flesh between them, is an advantage.   It’s a big spot that’s like a sound barrier.

Sound moves at a specific rate, thus, it will take a sound coming from a specific direction, just a teensy bit longer to reach one ear than it will the other ear.   It can’t simply pass through the soundproof head, so its got to go the long way.   That means that our brains can measure the difference in time it takes for a sound to reach both ears, triangulate, and figure out accurately, where the sound is coming from.   Try it, it works.   Without any effort, with your eyes closed, you can tell if a sound is over or under, to the left or right, close or far.

Out in the open country, you don’t necessarily need that degree of accuracy.  All you have to do is pick up a sound from somewhere, and then start looking with peripheral vision.   In a complicated environment though, you lose peripheral vision, you may not be able to turn your head to look, and the thing that is making that sound may be sneaking up on you.   So being able to accurately locate the source of sounds becomes very important.   After all, if something is sneaking up on you and makes a noise, you want to be able to run away from rather than accidentally towards it.

So the ears migrate to the sides of the head, where they’re perhaps less effective at picking up every little thing, but they’re a lot more effective at instantly telling where it is coming from.

Of course, in a complicated environment, the powers of sight and hearing are more limited.  But scent becomes more important.  Complicated environments mean that there are more things to smell, there’s more surfaces to hold smell, there’s less steady air currents to sweep scents away.  Thus, the nose gets larger and more sensitive.

Now, a few final thoughts complete our description of the Great White Ape face.   Diet.   What is the Great White Ape eating?   Or who is the Great White Ape eating? 

The Green Men have their remarkable tusks because they are a highly specialized predator, they’re designed for ambush attacks on the soft parts of prey who are as big or much bigger than they are.   Without that specialized prey, they wouldn’t have those specialized tusks, and you’d get a more normal set of fangs and teeth.   The White Apes obviously don’t have that specialized, open country, big herd, big game type of prey.  So they get a more normal set of fangs and teeth.

On the other hand, the Green Men are obviously living on a high meat diet, so their jaws don’t have to be all that powerful.   Yes, a steak can be tough.  But try living on wheat or grass or foliage for a while.   It takes a powerful lot of chewing to get that stuff processed, and it will wear your teeth right down.   Alternately, if you’re not a big game hunting specialist, you might be a scavenger, in which case, you’ve got to make do eating gristle, cracking bones, and chewing on the not so chewable portions of anatomy.   If you’re a predator working with smaller game, then you’ve got to eat a lot more of your small game for a meal.  You can’t just stick to the choice parts, fill your belly and leave the rest for scavengers.    Bring down an antelope, and there’s more than enough meat for your meal, you share it around, leave it for scavengers.  Bring down a rabbit... and to fill your belly, you need to eat the whole damned rabbit, which includes bones, hide and gristle.

So, the jaw gets bigger and heavier, because you have to do a lot more chewing.  And to increase the strength of the jaw, for things like cracking walnuts and bones, you run the muscles up to the head and anchor them with a sagittal crest.   The result is a powerful heavy jaw, sort of like a Gorilla has.   There may be a small side effect there, because, what with running muscles up to and anchoring them a the top of the head, you’re cutting down on space available for the brain.   Is this an issue with White Apes?   I’m not sure.  Ras Thavas and Pew Mogel had no problem packing human sized brains in there.

Those powerful heavy jaws suggest that the Great White Ape may actually be more omnivorous than the Green Man.   The Green Man is a predator born.  But with its powerful chewing jaws, the Great White Ape may be able to supplement its diet with plants, including fruit, roots, tubers, as well as insects, small animals and pretty much anything that might look like it can be eaten.

Of course, even if the Great White Ape is a strict meat eater, then its ecological position is probably that of the jaguar or the leopard.  They’re a jungle dwelling, complex environment predator.  They’re skilled at hiding or remaining concealed in their environment until they can get close enough to their prey and kill it...  By hitting it with a big rock or club.   But given how hit and miss their meals are, they probably have an extremely varied omnivorous diet.

The differing lifestyle of the White Ape is probably responsible for the attribution of greater strength and ferocity than the Green Man.    The White Ape is a climber, constantly on the move, and using its forward sets of arms to support its weight.   The Green Man, on the other hand, is more a ground walker, primarily using its legs and lower limbs and moving swiftly across countryside.   The White Ape as a hunter has no lethal attack, but must literally leap upon his prey and beat it to death.   Hence, the White Ape tends to more upper body strength, largely because of an active hunting lifestyle in complicated environments.

On the other hand, it’s a matter of perspective.   As we’ve seen John Carter records an instance where he is captured by Warhoons and witnesses two Green Men battle to the death.   At the end, one of the Green Men escapes defeat by using his tusk to disembowel his enemy, literally ripping him open from crotch to stern.   Imagine the sort of inbuilt strength it would take, especially for an exhausted warrior, to do that.   You go out and try disembowelling a man with only a knife clenched between your teeth...   Actually, don’t.  Just take my word for it that it would be appallingly difficult.   I think that what we’ve witnessed is the ancient Green Men killing technique, doing what their bodies were designed to do.   Against such an attack, even a White Ape might hesitate.   Thus, we can’t really say that the Green Men are weaker than the White Apes, but merely that their strength and muscles have different emphasis.

The Great White Apes are probably less inclined to a social structure.   They do have social organization, as we’ve seen.  But let’s face it, the great big payoffs of big game hunting simply aren’t there.   Nor is cooperation in large numbers as necessary to hunting, at most, two or three will be all you need to hunt prey cooperatively.   More than that becomes unwieldy in a complicated environment, you start tripping over each other, and worse, you wind up having to share the meat in a small kill, so it hardly becomes worth it.    Its noteable that the hunting groups that John Carter and Carthoris encounter have always been small numbers of individuals, even pairs.   Others have noted encounters with solitary great apes.

The fact that Great White Apes actually do gather in larger societies is itself a remarkable thing.   Each member of the Great White Ape tribe has to bust its ass hunting and foraging solely for itself and perhaps a mate and a few children.   There is no communal food production, like agriculture or livestock herding, so not only is there less incentive, but the size of the community that lone hunting and foraging can sustain is limited. 

The Green Men can organize themselves into large bands and tribes, based on a lifestyle of animal herding, accumulating themselves into dozens or hundreds, with a tribal strength in the tens of thousands.  On the other hand, the White Apes cannot organize themselves past a certain number, before all the solo foragers and small groups start getting on each others nerves.

There is another factor that might have helped the Green Men become civilized and social with other Martian races, where the White Apes clearly cannot.   Remember that the Green Men’s environment was probably mixed herds in open country.   They were used to being around several over species, and indeed, used to cooperating with certain of those species.   They were certainly used to not trying to kill every creature they saw.   They were also pretty secure in their environment, it was hard to sneak up on them.   Finally, as nomadic wanderers, they were constantly moving into new environments, seeing new things.   The result was a fairly tolerant, live and let live attitude, that allowed for exploration and curiousity.    So, when the Green Men encountered Orovars or other humans, they didn’t automatically see them as threats or prey, just an odd and interesting new species in the environment.   Indeed, the human sized creatures may have been a bit too small to be automatically considered prey.

Now, contrast this with the White Apes.   They’re living in complicated environments, they’re not nomadic, they’re territorial.   We never see a White Ape out in the open, they like to hole up in dead cities or jungles.    They have to hunt for a living in a fairly poor environment, so any other living thing they see that is not a White Ape is potentially lunch.   They don’t have the luxury of co-existing with multiple species, and they don’t have the luxury of so many big critters that they can pick and choose which ones they do and don’t want to kill.   They basically are out to kill whatever they can kill.   And of course, in their environment, there’s always a risk of something like a Banth sneaking up and making a meal of them.   The result is that they’re not tolerant of any other kind of creature, including Green Men or humans like Orovars or Red Men.

It’s probably ironic, because if you looked at the two races at the beginning of their histories, it would have probably seemed like it was the White Apes who were going to go out and become civilized, and the Green Men who were going to spend the rest of their life licking thoat blood.

After all, it was the White Apes who occupied stable territories.   The jungles and forests which were the original homes of the White Apes probably were vastly wealthier biologically than the dead cities they currently inhabit.  So they would have easily been able to support larger populations, and cooperate on larger scales.   Their environments were also vastly richer in workable stone, clay, wood, bone and other material, so they had many more opportunities to develop technology.   Their brains were constantly stimulated by the challenges and diversity of a complex environment.   In short, they were a good candidate to get out there and build a civilization.

In contrast, the Green Men were nomadic wanderers following the herd.  There were a lot fewer resources like workable stone and wood in their environment.   And worse, because they were nomadic, they were doubly handicapped.    Their access to resources like workable stone and wood was going to be only occasional, whenever the herd wandered into areas with the right stuff.  Even worse, as wanderers, they didn’t have a base of operations where they could store their stuff.   They had to carry it around with them.  This put a hard limit on the stuff that they could manage to carry.   In short, it was pretty obvious that they weren’t going to get anywhere, and that the White Apes would always be the brains in the family.

What changed everything was the Green Men’s domestication of other animals.   Once that happened, they could sustain larger populations, they could move further and faster, and most importantly, they could carry much more stuff around.   Being able to move quickly from one area containing resources to other areas containing resources gave them access to a much greater diversity of raw materials than the White Apes, who were confined to the narrow territory of each of their tribes.   With more resources and more kinds of resources available, the Green Men could develop more complicated tools.  They might have even been able to develop metallurgy.

The White Apes simply got left behind.   Of course, its possible that the White Apes could have had their own leap forward.   They might have developed agriculture of some form, or domesticated smaller food animals, or come up with really good tools like bows and arrows.   They might have overcome the small size of their resource areas by trading with other White Ape tribes.

Perhaps they even did.   It’s entirely possible that the White Apes kept up for a while.   But there was no way they could compete out in the open country, that was Green Man territory all the way.   Meanwhile, they faced competition from another direction:   Barsoomian Humans.

Barsoomian Humans were smaller than White Apes, and could therefore automatically sustain larger numbers and occupy more habitats as hunters and foragers.   This gave them better chances of inventing agriculture.   And when the Barsoomian humans had agriculture, they could sustain levels of population and social organization which would allow them to push the White Apes out onto the margins.

Except there’s a problem.  Potentially, the White Apes were as smart as anyone else.  Why didn’t they invent agriculture themselves, or at least borrow it from these Barsoomian humans?  If they had agriculture, then they could sustain populations and social organization themselves, and being far bigger and stronger, they could then push the puny humans into the sea.   Why didn’t they?

Well, possibly they were just stupid.  Perhaps they reached the limits of their brain’s wiring or intellectual capacity and simply couldn’t go any further.   Or possibly, their environment and social development had given them a critical handicap.

You see, in their environment, the White Apes basically couldn’t get along with anything that wasn’t a White Ape.   If you weren’t a White Ape, you were either an enemy or you were lunch.   And even if you were a White Ape from a rival territory, then you were an enemy.

The Green Men, on the other hand, were good at getting along with just about anyone.  They lived in and around multi-species herds, and their meals were big enough to share....  Think about that.   The White Apes couldn’t get along with anyone, including their cousins the Green Men.  The Green Men could get along with anyone.... including Barsoomian Humans.

Now, if Green Men who were domesticating animals were periodically in friendly contact with Barsoomian humans who were inventing agriculture...  Then sooner or later, the Barsoomian humans would obtain domesticated draft animals.   And when that happened, it was game over for the White Apes.

The simple fact of the matter was that no matter how big and strong the White Apes were, there was no way that they were going to be able to match the horsepower of Thoat and Zitidar powered agriculture.   Moreover, they were disadvantaged in war, if the Humans or Green Men were fighting from Thoats.  And they couldn’t transport as much as far or as quickly.

Of course, the White Apes might have evened things out by obtaining Thoats and Zitidars.  But here’s their problem:  They couldn’t get along with anyone who wasn’t a White Ape.  Which meant it was a lot harder for them to obtain domesticated animals from other races, or even to work with domesticated animals.  Unlike the Green Men, their evolutionary history didn’t include tolerating other species.

So, as I said, game over.   The Barsoomian Humans would eventually take over and push them out to the margins.   The White Ape proto-civilization was strangled in its crib, and their culture never amounted to much.   If they’d done it right, they could have had their own dead cities to skulk around in.

Barsoom is a big place with a lot of nooks and crannies, so its possible that in some forgotten corner, a White Ape civilization did manage to evolve, or the White Apes successfully borrowed enough to get their own city going.   But at best, it was a minor sideshow.   History had passed them by.

Ultimately, the Green Men too were beaten out by the Barsoomian Humans who would come to dominate the planet.  But the Green Men developed their culture a lot further, and they had the agriculture unfriendly highlands to fall back on.   As a result, their civilization endured and although they were pushed back and pushed out, they were never as down and out as the White Apes.

So  now, the faces of the Green Man and Great White Ape are complete.   We know why they look like they do, and more than that, we can see how each is adapted to and shaped by its environment and lifestyle, giving them their respective stengths and weaknesses.

Given how carefully tailored each of them are to their habitats, it becomes impossible to say which of them came first.   Were the first species the White Apes, who went out onto the plains, tanned and developed into Green Men?   Or were the first species Green Men who went into the jungle, lost their tusks and turned pale?   It’s chicken and the egg, no way to tell.

And for that matter, where did they come from?   There is clearly no evolutionary lineage for them on Earth.   But are they truly Martians?  Or are they Venusians, from some other planet in the solar system, or even true aliens from other solar systems?

For my money, the Green Men and White Apes are true Martians.   Martian fauna includes a lot of strange creatures, including eight and ten legged monsters.   But it also includes at least two other six legged creatures.

In the polar wastes, we have the Apt, a sort of hippopotamous-centaur:

“An Arctic monster. A huge, white-furred creature with six limbs, four of which, short and heavy, carry it over the snow and ice; the other two, which grow forward from its shoulders on either side of its long, powerful neck, terminate in white, hairless hands with which it seizes and holds its prey. Its head and mouth are similar in appearance to those of a hippopotamus, except that from the sides of the lower jawbone two mighty horns curve slightly downward toward the front. Its two huge eyes extend in two vast oval patches from the center of the top of the cranium down either side of the head to below the roots of the horns, so that these weapons really grow out from the lower part of the eyes, which are composed of several thousand ocelli each. Each ocellus is furnished with its own lid, and the apt can, at will, close as many of the facets of his huge eyes as he chooses..”   (From the Barsoomian Lexicon )

There’s no sign that the apt is intelligent, it is merely a particularly ferocious predator.  But the six limbed quality suggests that it is related, however distantly, to the Green Men and White Apes.

Another distant relative is the Sorak, a cat sized creature which is used as a pet by Martian women and is apparently not too bright, at least according to an angry hormad in Synthetic Men of Mars.

"'What good shall I be,' he demanded, 'with only a head and one leg? They call you The Master Mind of Mars! Phooey! You haven't the brains of a sorak. When they produce their kind they give them a body and six legs, to say nothing of a head. Now what are you going to do about it? That's what I want to know.'"

Soraks aren’t well respected.   There are references to ‘dying like a Sorak’ which is apparently a rather dishonourable thing.  Dejah Thoris once said that John Carter was not fit to polish the teeth on her grandmother’s Sorak, but apparently, she got over it.

The Sorak, given its size and apparent lack of intelligence, seems a radically different creature from the Apts and Green Men and White Apes, all of whom are top of the food chain critters.  Yet, it too must have an evolutionary lineage, it has to come from somewhere, and it likely has ancestor and cousin species.

Meanwhile, although its never described, artists have depicted both Ulsios and Zitidars as six-legged creature.   In the case of Ulsios, there is an argument that Burroughs himself would have had an opportunity to accept or reject or at least comment upon these artists depictions, and didn’t.  But still, I think that with all due respect, I won’t place these creatures into anything more definite than a maybe category.

Now remember, Barsoom is a world which has suffered a mass extinction.  So we would not expect to find a lot of biological links.   Humans have a variety of relatives which connect us to other animals on the planet and show that we evolved on Earth.   From humans, we go to apes, apes are cousins to monkeys, monkeys to lemurs, lemurs to pro-simians, which then relate loosely to tree shrews, who relate to insectivores, who in turn are related to carnivores.

For Barsoom and the Green Men and White Apes, we have two closely related intelligent species, or perhaps a single intelligent species.  Then, because of mass extinction, there will be gaps all over the place.   But given that large chunks of the flora and fauna no longer exist, the survival of even a few other six-legged creatures like Soraks and Apts is a confirmation of an overall relationship. 

Green Men and White Apes had to come from somewhere, they were the product of an evolutionary line, and thus there must have been other animals like them.   Six legged apes and monkeys and proto-monkeys and god knows what else, all the way back to a founding species which we must presume was six legged.  Equally, Apts have to come from somewhere, they are the product of an evolutionary line, and so there must have been Apt cousin species, predecessor species, and even a root six legged species.

Now, perhaps there were three or four unrelated lines of creatures evolving six limbs, perhaps on different planets, all of which wound up on Mars.    That simply does not make sense.   What does make sense is to accept that if four six limbed species are all on Mars, then they are most likely related, most likely all branch off from a common evolutionary lineage, and are derived from a common ancestor.  In which case, they’re all Martians.

Nor is there much sign of a vertebrate six limbed evolutionary lineage on any other planet in the solar system.   In a follow up article, Tharks in Space I look at potential close relatives of the Green Men and Great White Apes in the form of six-limbed, intelligent giants on Earth and Venus in the stories of Burroughs, Otis Adelbert Kline and Ralph Milne Farley.   However, these creatures, being intelligent, may be direct offshoots of the Green Man/White Ape line who were intelligent enough to travel space, either physically or by projection.

There are also the Weiroo of Caprona and the Angans of Venus, who may or may not be six limbed.  They have four limbs and a pair of wings.  But the wings may be derived from a different evolutionary pathway.

In terms of six-limbed vertebrate animals on other worlds, there is only the Tongzan of Venus, described thusly:

“In the dim half-light of the Venusan night I saw confronting me a creature that might be conjured only in the half-delirium of some horrid nightmare. It was about as large as a fullgrown puma, and stood upon four handlike feet that suggested that it might be almost wholly arboreal. The front legs were much longer than the hind, suggesting, in this respect, the hyena; but here the similarity ceased, for the creature's furry pelt was striped longitudinally with alternate bands of red and yellow, and its hideous head bore no resemblance to any earthly animal. No external ears were visible, and in the low forehead was a single large, round eye at the end of a thick antenna about four inches long. The jaws were powerful and armed with long, sharp fangs, while from either side of the neck projected a powerful chela. Never have I seen a creature so fearsomely armed for offense as was this nameless beast of another world. With those powerful crablike pincers it could easily have held an opponent far stronger than a man and dragged it to those terrible jaws.”

It appears in Chapter 2 of Pirates of Venus.   Another specimen is seen again, in Chapter 39 of Escape on Venus.   Carson is quite correct when he relates that it resembles no form of Earthly life. 

On the other hand, it has no resemblance at all to any other Venus life, and this is very peculiar, since unlike Barsoom, Venus has not gone through a mass extinction.   So if the Tongzan was truly native to Venus, we should be seeing some relatives, other examples of a six limbed lineage.  We don’t.   Of course, neither Burroughs, nor Kline’s nor Farley’s Venuses are thoroughly explored.  So its possible that the Tongzan has a few relatives floating around that we haven’t met.  Or maybe not.  All we can record is their absence.

(Farley does record giant six-limbed insects, including an elephant- or bear-sized ant lion, in the land of Cupia on his Venus.  But these seem to be hard shelled insects and not a vertebrate, endoskeletal line.  So for now, we can dismiss them as being unrelated to Tharks and unrelated to the Tongzan.   But then again, is it proper to bring Farley in at this stage?  Either way, it’s the only other line of six-limb creatures in either Farley or Kline’s work.)

The creatures the Tongzan most resembles (inside or outside Burroughs) are the six limbed evolutionary line of Barsoom.  Its likely not a close relative of the Tharks, but it may be from the same family line, much as Apts or Soraks.  So, the question is, what is it doing on Venus?  Did space traveling Barsoomians bring its ancestors as pets and accidentally leave a few behind?  Is the Tongzan a Barsoomian Sorak reverted back to a savage large predator, the way a species of house cat might conceivably revert back to a large puma-like hunting cat if left in the wild for a few thousand years?

It’s equally possible, perhaps probable, that the first proto-Tharks looked much different, facially, than either Green Man or White Ape.   Possibly both species are derived from a common ancestor, rather than one being an offshoot of the other.   As to what that face may have been like, who knows.   It may well have looked much more human than either race does now. 

Indeed, if the proto-Tharks were the result of an astral projection gone wrong, then its entirely possible that they looked quite human in some respects.   The proto-Thark may have started out as a human beings astrally projecting to Mars, whose body, when they materialized, were heavily shaped or influenced by the six limbed life forms then existing.    The process of materialization may have incorporated six-limbed DNA, sort of like Cronenberg’s movie, The Fly.

Of course, this raises some interesting questions.   If both White Apes and Green Men, and possibly other races like the Blue Warriors, Black Formians, White Sabits, Whistling Bees, Blue Apes,  Pellucidar Ants and Centaurs all sprang from common ancestry, then how long, exactly would it take for them to diversify to the examples we’ve seen.

How long would it take to get a Green Man and White Ape?   Perhaps not that long.   Remember that the six-limbed creatures reproduce by egg.    According to John Carter, each female adult Martian can lay thirteen eggs a year, and these eggs mature into adult Martians in about ten years.

Now, compare this with humans.   A female human can produce about one child per year, each child demands a major investment of time and resources and takes about fifteen to twenty years to rear. 

So, a human family will produce, perhaps six to ten children over ten or fifteen years, if it’s a large family. 

Meanwhile, a Green Man couple could produce in that time between 130 and 200 eggs.   More offspring means more diversity, more opportunities for mutations and adaptations.   So, within the same time span, a Green Man couple will have twenty to thirty times more possible variations and adaptations.

There are other factors.  Humans grow slowly, and it might take as much as twenty years for a person’s unique qualities or adaptations to become fully apparent and useful, at which point, they start to outbreed their competitors.

On the other hand, Green Martians can, with almost supernatural insight, assess their eggs or larva within the first five years, discovering qualities of fitness or adaptation.   And they’re essentially mature within ten years.   So beneficial adaptations will be discovered and encouraged anywhere from two to five times as quickly as in humans.

Finally, it takes humans anywhere from 15 to 25 years to reproduce.   Green Men become reproductively competent at around 40 years.    This means that the generations turn over at about half the rate, positive mutations or adaptations begin to proliferate at about less quickly.  So this slows down the process.  But the other variables keep it high.

What does all this mean?   Well, essentially it means that the speed of change or adaptation or evolution among Green Men, and presumably White Apes and other possible Thark species can happen at a much faster rate than humans.   Anywhere from 20 (20 x 2 x .5) to 75 (30 x 5 x .5) times as quickly.

This means you could wind up with apparently major differences in very short times.  Differences which might make the differences between bulldogs, wolfhounds, greyhounds and daschunds seem trivial. 

As far as skin colour goes, humans have radically changed their skin colours with only a few thousand years of separation.   The proto-Tharks reproduced and grew far more quickly than humans, their rate of potential mutation was therefore much higher and their generations were shorter.   So the changes in skin colour could have happened in a flash.

Apart from that, the only significant differences are facial, and these are merely differences of position and proportion.   It’s not like one race has completely different senses, or no nose, or four eyes.   Rather, both Green Man and White Apes have two ears, two eyes, nostrils, a mouth and teeth with canines.   So we’re just talking about emphasizing certain features, canines into tusks, de-emphasizing certain features like Green Man noses, eyes adapting, etc.   It’s quite possible that these changes could have been extremely rapid by human timelines.

Given this potential rate of change, the Green Men and White Apes (to say nothing of Blue Warriors, Blue Apes, Formians and Sabits) may be only a few thousands or tens of thousands of years apart.

One small note that I’d like to address in terms of the way Barsoomian life is depicted.   The renditions of Thoats, for example, are almost certainly inaccurate.

The way Thoats are usually drawn, they are musclebound and so short that their legs are literally falling over each other.   This animal can’t possibly run, it would trip over itself in a hundred yards.  And it is certainly not as bulky and muscular as drawn.

Consider it this way.   The thickness of an animal’s legs are proportional to its weight.  Big heavy creatures like Rhinoceri, Hippopotami and Elephants have thick heavy legs.   Smaller creatures like Deer or Antelope or slender graceful legs.   Horses and Moose and Giraffe are comparatively big animals, but their legs are still quite slender.

Now, take it to Mars.   Barsoom’s gravity is 38% of earth’s.   Thus, everything there only weighs about 40% as much.   Thus a two ton Rhinoceros on Earth will only weigh about 1600 lbs, or about as heavy as a big horse or a moose.   Thus, instead of its thick bulky legs, a Rhino sized creature could get away with slender horse or moose legs.

But there’s more to it than that.   A Rhino has only four legs.   So, each of the Rhinocerus legs, when its standing still, is bearing 1000 pounds apiece (2 tons = 4000 pounds, divide by four legs).   Well, a Thoat has 8 legs, a Banth has 10.   So a Thoat or a Banth which has the same mass as a rhinoceros, would weigh only 38% as much, and would distribute that weight over 8 to 10 legs. 

Thus, our Banth with the mass of a Rhino is sustaining its weight at about 160 pounds per leg, and the Thoat is barely heavier, supporting 200 pounds per leg.   Compare this to a big horse, which supports 300 to 400 pounds per leg.   Thus, a Banth or Thoat with the mass of a rhinocerus, could trip lightly around on graceful gazelle type legs.

Green Martian Thoats are the size of elephants.   Now let’s assume that an elephant on earth masses 4 tons (8000 lbs) , resulting in 1 ton (2000 lbs) per leg over 4 legs.   On Mars, the Thoat sized elephant weighs in at 1.6 tons (3200 lbs), resulting in 0.2 ton (400 lbs) per leg for 8 legs.   Thus, a Thoat the size of an elephant will not have elephant legs, but horse legs.

Go to smaller creatures like Calots, the size of a mere pony, and your legs should  be slender gazelle or dog-legged structures.   That’s more than ample to support 40% weight distributed over ten limbs.  Of course, the Calot is described as having thick legs.  This implies either that the Calot is a dwarf version of a far larger original, or that all those muscles and thick bones imply incredible speed.

Another feature to keep in mind is length.   Look at terrestrial animals.   Most animals have a body length approximating their leg length.   That is, that they’ve got space between their front and back legs roughly equal to the length of their legs.   Why is this?   So that they can move most effectively.  Each limb as it moves, describes a part of a circle an ‘arc’ of movement.   In order to avoid accidentally kicking itself, the front and back legs have to be outside of each other’s ‘arc’ of movement.

This means that a Thoat can’t be simply horse proportioned with a couple of extra sets of legs stuck on in the middle.   Rather, it must be stretched out so that each set of legs will have room to move.   Thus, Thoats, Banths, Calots, etc., must be at least twice the body lengths, of terrestrial creatures, just to have minimal room to move.

So, Barsoomian creatures, as a general rule, should be long and slung, with slender graceful limbs.

John Carter, with respect to Tharks, observes that they are only muscled for their gravity, which is slight.   That’s a tip.

Let’s keep this in mind, folks.