What evolutionary pressures would lead to Goblins?

Question

A long time ago homo floresiensis split off into two main groups Goblins and Halflings. Now Goblins are an odd little bunch (here's a rough mock up of what a goblin might look like) and I was wondering what evolutionary pressures would lead to Goblins? some basic characteristics of goblins are:

• are as intelligent as humans (don't have any behavioral differences compared to humans)
• are 112.7cm (3.7ft) tall
• have large noses
• have big pointy ears
• have an improved sense of hearing and smell but do have slightly worse eyesight
• have green skin due to a symbiotic relationship with a type of moss or algae
• have life spans similar to humans though they do reach sexual maturity a bit faster than humans

Note: magic does not exist in my story.

Answer 1

Island Dwarfism

Like Homo Florensis, which you stated to be an ancestor in your question, living on an island in which food is relatively limited has selected smaller body size for your goblin population.

Extremely Dense Jungle

The underbrush of the jungle is thick, visibility is reduced due to foliage and it’s somewhat dark due to the shade.

Their small size is an advantage in the dense underbrush, as they can scamper quickly and quietly through it.

Because visibility is lacking, they rely on smell to find edible plants and grubs, and hearing to detect stalking predators and slightly larger prey like rodents. Their eyesight is weaker due to more of their brain being dedicated to smell and hearing, and it’s simply not as useful.

Their green skin has been selected for due to its camouflaging effect in the dark green jungle, as they are prey in this dark forest.

Intelligence

It’s hard to be small and weak, but even the strongest predator will fall to arrows and spears. Like humans, intelligence has been continually selected for.

In short, an equatorial island covered in dense rainforest would be the most likely conditions

Answer 2

1. are as intelligent as humans -> Covered in part 5
2. are 112.7cm (3.7ft) tall -> from your own link, that is the size of homo floresiensis, so what you really need to do is make sure that the goblins don't evolve to increase in size over time. The typical way to do this is be on an island without large predators, but also throw in some scarcity of resources. If you had a warm climate, this would also ensure that the Goblins wouldn't need a large body size to regulate heat.
3. have large noses -> You could get this by increasing the heat of the location of goblins. Part of the feature of a nose is regulating heat/moisture of air coming into the lungs. Typically though you have a trade off. It is either long/narrow nose (cold climate) or wide and short nose (hot climate). If you had a hot climate and sexually selected for nose length, seems like a likely outcome.
4. have big pointy ears -> This answer highlights the benefit of a pointy ear which "may be useful to them in triangulating sound sources; perhaps higher or lower frequency sounds than in the human range". The solution for this one could be there is a certain animal/critter/plant that is highly nutritious/functions as a drug/etc, that emits a sound in such a high frequency that only pointy ears would be able to hear. The Goblins would be evolved to hear that animal or plant make the noise and have some pointy ears for it.
5. have an improved sense of hearing and smell but do have slightly worse eyesight-> improved hearing is covered in point 4 by the pointy ears (hearing additional frequencies is improved hearing in my book). It is suggested here that the sense of smell is "processed in the same brain regions responsible for processing emotion, motivation, fear, memory, pleasure and attraction" indicating that human and goblin cognitive abilities are loosely tied to smell. You could also make the majority of Goblin food be stationary, but hidden (like worms underneath the earth). This way Goblin food is found more by scent than by vision making the trait of smelling more selected for instead of vision for survival. Coupled with the fact that there are no large or super dangerous predators on Goblin island, there is no need for keen vision.
6. have green skin (possibly due to a symbiotic relationship with a type of moss or algae) -> The only animals I know of that are green like bugs, frogs, snakes, iguanas, are usually animals that don't move much and blend in with the environment to wait lurk for prey. Which would seem to conflict with the whole intelligent creatures that have a society vibe. Also conflicts with the size nerfs (as the lack of large predators will keep the size of population down by neglecting to select for size).
7. have life spans similar to humans though they do reach sexual maturity a bit faster than humans -> There is some debate as to why some species live as long as they do with quite a number of theories. The only thing I can think of would be to have the metabolism and development of a Goblin baby to be incredibly high and then drop off dramatically when reaching adulthood. This way, they could age quickly to mature and then go on to live about as long as a human.

A large island, warm climate, scarce resources, natural Goblin food is either in the earth itself (worms/grubs) or hidden in some other way and has distinct odor, no large predators,

Answer 3

Consider goblins in the traditional role of dragon fodder and servants. Since I looked at orcs and mentioned they wouldn't be good laborers, perhaps goblins developed closely with orcs to fill the need for labor. If proto-goblin/halflings were enslaved by orcs, prolonged servitude under an aggressive and physically more powerful species would lead to a selection of individuals who were efficient at tasks but not physically large, powerful, or who even felt safe looking up at their masters. Eyesight might suffer if there were no advantage. Hearing would be important to anticipate tasks and avoid brutal punishments. A good sense of smell is important to separate safe from unsafe food when all you get are scraps. Green skin might be useful in any natural setting where the goblin would need to avoid being noticed or even a distinguishing characteristic to make orcs feel superior (depending on orc coloration). Sexual maturity could result from long-term pressure for goblins to give birth early to new slaves. Think old south. Pointy ears and long noses have as many possible reasons as there are ethnicities.

Answer 4

As stated by others, island dwarfism or selective breeding could explain the Goblin's size not growing past that of an ordinary Homo Florensis.

Their big noses and ears could easily be explained by living in a dark area; Nixoncranium mentioned dense jungle underbrush. I would like to add caves, though, because small size would be an advantage when chasing prey through small tunnels and eyesight would be practically useless there.

While eyesight would be pretty useless in caves, hearing and scent would be incredibly useful; as evidenced by the Crawlers in The Descent, who navigate almost solely by those senses. Their poor eyesight can also be explained by this quote about bat's sight from usgs.gov: "No, bats are not blind. Bats have small eyes with very sensitive vision, which helps them see in conditions we might consider pitch black. They don’t have the sharp and colorful vision humans have, but they don’t need that. Think of bat vision as similar to a dark-adapted Mr. Magoo (a cartoon character with very poor vision)."

Finally, caves are relatively scarce in resources, so the goblins will likely go foraging. This makes sight useful and therefore ensures it will be retained; but since sharper eyesight isn't an advantage in light-poor caves, it will remain poor throughout generations.

Green skin could be explained by:

1. Fungal layer-Caves come with fungi, it's quite plausible that the goblins, due to an unsanitary lifestyle, are coated in their very own layer of fungus.

2. Vestigial trait-Perhaps one of the Goblin's ancestors ended up with green skin and the Goblins kept it; it didn't hurt anything, so it stayed (like the vestigial claws on pythons).

3. Camouflage-When Goblins go out to forage the forests around their caves (I assume there are forests around their caves) green skin helps them blend in. This mutation arose out of nowhere generations ago, and since it kept the goblins who possessed it alive (as opposed to pale goblins, who stick out like sore thumbs except on, say, snowy mountaintops.)

4. Pigment Retainment-Perhaps the Goblins eat an awful lot of plants and green fungi. Regular humans can turn orange by eating an awful lot of carrots; a similar phenomenon could make Goblins green.

Their quick transition to adulthood could be explained by a harsh environment that makes lifespans relatively short for the vast majority; look at humans in the Dark Ages, which rarely lived to forty, or even thirty-two. The Goblins that reached sexual maturity faster were the ones who had offspring before natural selection got them, so that trait was found in all the survivors.

Later on, the Goblin's growing intelligence increased their safety and quality of life (and therefore their lifespans), and the Goblins who lived longer had more offspring, therefore outcompetiting their shorter-lived relatives. Finally, longer lifespans didn't cause a resurgence in slower-maturing Goblins since that trait had been (quite literally) killed out of the gene pool.

Answer 5

Imprisonment, torture would be the most effective way. Also being kept in harsh environment they are not naturally suited to would help as well. Being kept in very small spaces would prevent growth.