How would multi-race humanoid evolution happen?

Question

If we were to pull the following races out of a D&D players handbook and remove them from the setting/history of Faerun and look at them from a biological/non-magic perspective (no other planes of existence, no Fey realm etc etc etc)

• Human
• Elf
• Halfling
• Gnome
• Dwarf
• Orc
• Half Elf
• Half Orc

I feel it is logical to assume that the races all branched from a common ancestor, after all it is statistically fascinating that humanoids evolved at all.

What I want to know is:

1. What would the evolutionary tree look like? (A diagram like the one shown below would be excellent.)
   
   (Original Source: http://palaeos.com/systematics/tree/images/treeolif.jpg)

2. What factors (non-magical) would drive the evolution of such varying humanoid species?

Answer 1

After some in-depth research into the development of various humanoid races, I've developed a corpus of theory as to their development. Upon my return from their habitat, I plan to publish the following in some sort of respectable journal, perhaps the Journal of Edible Races. While snoozing off their weekly dinner of ponies, I'm sure the other dragons will enjoy reading it over:

Naturally, all the humanoid races descended from some common bipedal primate. Since then, however, they have evolved into two species, with a total of five subspecies (plus three common hybrids. Broadly, these can be divided into the larger-statured humanoids: the humans, orcs, and elves, and the smaller statured humanoids: the dwarves and halflings. These two populations are not known to interbreed and produce offspring, so they should be considered separate species, but the subspecies interbreed regularly, producing some interesting hybrids.

Homo Sapiens

Humans (Homo Sapiens Sapiens)

Humans are predominantly farmers in fertile regions. They are believed to be the least differentiated stock of the homo sapiens branch of humanoids, being smaller than the hill-dwelling orcs and larger than the forest-dwelling elves. Over the past few million years, they've been engaging in low-level farming from small villages, trading regularly with both orcs and elves for resources. Recently, they've begun to domesticate some wild horses, which are driving both the development of larger societies and rapid technological improvement.

Orcs (Homo Sapiens Moria)

The orcs, unlike humans, do not rely on farming. They form hunter gatherer clans in upland regions inhabited by large animals such as oiliphants and griffins. It's believed that their hunting of these creatures has led to their evolving much stockier frames than their lowland counterparts. The breed freely with humans, producing half orcs.

It's not known if orcs and elves would be capable of producing offspring, as they do not regularly come into contact with one another. If not, then homo sapiens is a fascinating example of a ring species.

Elves (Homo Sapiens Lorien)

Elves have adapted to forest life, with small, slight bodies but surprisingly powerful arms. They live largely in homes built in the branches of large trees and coming down to the ground to hunt for game and to collect fruit.

In general, elves undertake these activities at night, possibly due to the presence of bands of forest-dwelling humans during the day. This nocturnal/diurnal duality allows elves and humans to coexist peacefully, and has also driven the elves to develop larger ears and pronounced eyes to better sense in the dark. They interbreed with humans where their ranges overlap, but this is looked down on by both humans and elves, probably due to the facts that elven frames are poorly suited to farm labor and that humans don't operate well during twilight hours.

Homo Dwarfus

Homo dwarfus has two subspecies: the dwarves and the halflings. These two races can interbreed, with the cross generally being referred to as the gnomes.

Interestingly, unlike half-orcs and half-elves, the gnomes have formed their own societies of multi-generational gnome families. It's viewed as likely, based on this, that they may develop into what could be considered a subspecies of homo dwarfus in their own right.

Dwarves (Homo Dwarfus Dwarfus)

Short and stocky, the dwarves have evolved for life underground. Like orcs, they are commonly found in hills and mountains, but have opted for a different evolutionary path.

Dwarves build elaborate warrens beneath the Earth, bringing many families together for mutual defense and child rearing. Moving through both natural and artificial tunnels has selected for short, powerful frames with large noses for drawing in more of what is often poor quality air. Dwarves have evolved a farming culture similar to humans, but in absence of good food crops growing on the surface, the dwarves have taken to gathering nutrient poor plant materials, such as grasses, in large store rooms underground. These materials are then used to grow nutritious mushrooms, as well as to brew alcohol in great quantities.

Unfortunately, the same behavior that has brought about these fascinating behavioral changes has also given dwarves a keen interest in mineral treasures, as is known by dragons across the land who have had to deal with dwarf infestations in their treasure chambers.

Halflings (Homo Sapiens Hobbitus)

Some dwarves, however, have moved back to the surface, and evolved into a small race known as the halflings. While retaining the burrow-building behaviors of their ancestors, halflings have moved to lowland areas where they have learned to farm from nearby humans. While incapable of interbreeding due to having fully speciated, humans and halflings form intermingled societies in some areas, with halflings appreciating the protection their larger neighbors provide and humans enjoying the fact that generations of life underground have left the halflings as experts at digging and brewing a large variety of fermented drinks.

Halflings, without the pressures of a harsh life in the mountains, are generally slighter of build than dwarves, and have lost the exceptional senses that dwarves have developed for a life underground.

Unfortunately, some halflings seem to have retained the dwarven penchant for treasure. Care should be taken to make sure that any halfling populations living in the vicinity of dragons do not become a nuisance.

Gnomes

In areas where halflings and dwarves live somewhat close together, they occasionally crossbreed, giving birth to hybrids known as gnomes. Gnomes retain dwarven senses, but with the slighter builds of halflings. In many areas, they've taken up roles as go-betweens for these two groups, as well as trading with any humans, orcs, and elves in the area.

In their wide exposure to many cultures during their lives as nomadic, traveling merchants, the gnomes have also picked up a penchant for combining and improving upon inventions created by the other humanoid races. They've also gained some sense in their travels, rarely pilfering from the homes of dragons, though this fact should be well known to anyone in posession of one of their excellent anti-dwarf horde security systems.

Answer 2

A few things must be considered.

1. In most settings, all if not most of these races can interbreed.
2. In most settings, nothing is said whether mixed races can also breed again. In some, it is known that they can, and due to lack of a negative answer in others, it may be concluded that most if not all of the mixed races can generate fertile descendants.
3. Mixed races show intermediary traits between the two ascendants.

Thus, it would be safe to conclude that all of these races are of the same species: Homo sapiens.

Their phenotypical differences would be a result of geographical isolation that would intensify certain traits according to the environment. Some traits may be pure genetic variance (Like long and pointy ears) and others would rise due to environment pressure.

So, if I would guess:

1. Humans: You'd have to think about the same factors that created differences between human races/ethnicities. Straightforward.
2. The general description of an elf suggests a body fit for less hostile environments (Not being so physically robust), where food and shelter is plenty and easy, or forests. Lighter bodies are better to move around in trees and cliffs. For the worlds where elves are shorter than humans, it could suggest they came from an island zone.
3. Halflings can be pygmies. They'd probably come from an island, oasis or other small, isolated region (Google Insular Dwarfism)
4. Gnomes would be a mid term between a halfling and a dwarf.
5. The dwarf stature could also be due to insular dwarfism, but a good explanation is also that their small, stocky builds are better suited for moving inside caves which they originally couldn't shape to their desires. But that would also have to result in less hair and higher-sensitivity to light (They'd see well in the dark but bad in the light).
6. Orcs would come from very hostile, harsh regions. Period. Everything in them suggests a need for a strong, aggressive predator. Probably a desert, steppe or mountains. Little food, lots of other predators, hard preys.
7. Half orcs and half elves are interracial and would show traits of their parents.

AND

In the case where they're from different species, but very close genetically that they can breed but can't generate fertile descendants (Such as the Mule and the Liger), the same rules as above would apply. Then, Dustin's cladogram would apply, and they'd all have a recent common ancestor.

But my guess is that the genetic difference between this races is the same as the difference between different dog breeds and between dogs and wolves.

Answer 3

Look at the history of Earth. The following is a diagram of the human evolutionary tree.

As you can clearly see, at least five races evolved that could be identified as humanoid with some concept of free thought. The conditions required for a world with that many coexisting races to exist would be for all of the races to have certain evolutionary benefits. An example would be Neanderthals being better equipped for cold weather and surviving in Europe for Millennia. Make each race overly adept at living in the area in which they originated, then they cannot outcompete eachother in their respective habitats.

Answer 4

It is clear that elves, men, and orcs are members of a single species. Dwarves and gnomes, while unquestionably related, have completed speciation and do not interbreed as members of the H. sapiens subspecies do. But halflings are more closely related to elves and humans than the most recent common ancestor of dwarves and gnomes, which creates this phylogenetic tree:

It is evident that the gigantism of humans is an innovation not present in the basal demihuman.

The only remaining issue is the placement of elves and orcs relative to humans. Casual study suggests many similarities between elves and humans, but the anthropological literature [T54] suggests that elves and orcs are quite closely related and thus these superficial similarities are merely the result of convergent evolution between elves and the human outgroup.

[T54]: J. R. R. Tolkien, The Lord of the Rings (1954).

Answer 5

The body adapts to changed circumstances. What changes circumstances? The mind does. So one evolutionary fork reason, are diffrent hardcoded mindsets. What might coexist for a while, may grow independent over time, as adaption to the new circumstances set in.

For example- you are always slightly depressed, you like darker places and thus you would love to live - rather alone - for the rest of your live in a cave. This mindset is, if encoded in culture, and a dominant trait, what forks a new species over time. The species would become pale, adapt to hunting in the dark, growing fungi, etc. And might fork again.

Always remember, that forkindependece, the question wether a fork may break free of its original society, or become sort of cylcic regenerated subcaste depends on several sidefactors. Is the fork tremendously usefull to society even though maybee not reproductive? Could the fork cope alone?

Also be reminded that evolution, aka the adaption to circumstances, can if your group dominates the enviroment, mean that you adapt to the survival mode of your group. A always overreproductive group may cause a endless series of civil war, and adapt thus to a species that recovers fast from this wars, and where every individual trys to get as many cards as possible into the giant genetic lottery that is civil war. Over time that Circle would be optimized away.

A technological advanced society in turn, may suspend this cycle indefinatly, or disolve it alltogether. Though distant instincs may remain and resurface.