Anatomically Correct Gnolls

Question

Since we're dealing with cat-folk already with the question about the Khajiit, I figured we'd toss a different evolutionary lineage for furry humanoids around, that of the hyena.

Ever since the early days of D&D, the gnoll has been a most curious creature — a ravenous, bipedal, somewhat-social hyena-folk, as depicted below.

What would the evolutionary path be from the hyenas (presumably the spotted variety, as the rest are pretty strictly antisocial) we know (and occasionally love) to such a race be? Also, what behavioral features would develop, and what physical features would develop or be lost during the course of this evolution?

As always, here is the rest of the Anatomically Correct Series.

Answer 1

Evolution

We start as you said with the spotted hyena, already a social scavenging animal, we only have to talk about its intelligence. Hyenas are actually much smarter than their stereotype suggests, in fact studies show that hyenas use wide diverse methods of opening man made boxes and also use trial and error in opening the box.

A few differences (that are very important) I have noticed between Gnolls and hyenas other than what you mentioned; the limbs. A hyena arm is much longer, more equal along its segments and has pads instead of hands. The evolution from hyena limb to Gnoll limb requires a method similar to primates;

1. Hyena - the hyena mainly scavenges off of other predators, in the case of a shortage of food in certain areas, these predators are much less likely to leave scraps. This means that mister hyena has to hunt on its own and is now a competitor of the bigger predators. The New, more hungry Lions are likely to chase out the hyena and that is where we get stage 2.

• Proto-Gnoll - above is a map of where the Spotted Hyena can be found, the big patch of white is mainly jungle. This is where we are going to want our hyena to become a proto-Gnoll, still similar in many ways to the hyena, but the limbs are.... different. To make best use of their new jungle area (where predators are farther and fewer inbetween) their paws become more segmented to allow for tree grip, while their legs remain digitigrade in order to quickly run after prey or away from predators. Eventually they lose the whole final paw segment (which is the hyena equivalent of a foot), replacing it with a fully formed, human-like hand.
• Gnoll - Finally our Proto-gnoll looks like a Gnoll, but we still have to evolve sapience. Luckily based on our aforementioned Proto-Gnolls evolutionary history, we can treat them as carnivorous humans that can run fast. Which in turn means we can just say they evolved sapience just as humans did.

Specific Anatomy and behavior

• Manes. Some Gnolls possess crestlike manes of hair going from their head down their spine which rise up they become frightened or angry. The mane can be explained easily through sexual selection, but having the main rise is harder. Lions fur doesn't rise when they get aggressive and they are one of the few animals with manes. So I cannot help here, but I would say the mane bristling is within reasonable doubt.

• Loyalty. Gnolls are brutal hunters with a demonic ancestry who are fiercely loyal to their pack. Again Hyenas are not truly loyal pack hunters, they are pack scavengers. But the problem holds the answer, If we have or proto-gnoll evolve to be a pack hunter with a pack leader and we will have loyalty down. This behavior evolution coincides with their new jungle environment and its predators that don't leave corpses lying around.

• Age. Gnolls reach adulthood by the age of 5 and live to around 30. In zoo's Hyena's live for an average 12 years and a maximum of 25 years. So the age isn't out of the question.

• Size. Most gnolls are over 7 feet tall. Similar to how humans evolved height to look over talk grass, then when the gnolls leave the jungle, the height can only benefit their light frame.

• Darkvision. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. Considering that the hyena is already nocturnal, this, like the age is already handled.