Morlock

In The Time Machine
Morlocks are one of the two post-human races in H.G. Wells' The Time Machine. Set in the year 802,701 AD, the Morlocks lived in a troglodyte civilization, characterized by caveman behavior.

In The Time Ships
The Morlocks are still a race existing in darkness but are no longer brutish. Due to a second timeline they have achieved great technological advances and dedicated themselves to gaining knowledge of the universe.

Biology and Appearance
The physical features of the Morlocks are the result of thousands of generations of living without sunlight. They have dull grey-to-white skin, chinless faces, and large greyish-red eyes that reflect light.

The protagonist of the story, the Time Traveler, finds out later on that the Morlocks and the other post-human race in the era, the Eloi, maintain a relationship characteristic of many present-day organisms. The Morlocks, having been used to heavy labor and what was left of technology, feed and clothe the Eloi. In return, the Morlocks eat the Eloi. It may seem that the Morlock-Eloi relationship is like that of a farmer and his livestock.

Little is seen of their society in 802,701 A.D., but when the Time Traveler attempts to rescue the Eloi Weena from them by travelling back to their time he finds that the timeline has been significantly altered. After arriving in 657,208 A.D., he finds that the sun has been encased in a sphere and the Earth, though still having a breathable atmosphere and heated by its core, has been plunged into darkness. It turns out that it is now a nursery for Morlocks, and the Morlock species itself, instead of being carnivorous brutes, are now a highly advanced civilization living within the Sphere that encircles the sun. Their appearance is largely the same, but some are taller due to living in areas of the Sphere that have lower gravity.

Evolution
Morlocks are said to be humanoid creatures, descended from humans. Through time, they have evolved into a different species better suited to their subterranean habitat. They possess characteristics of apes with little or no clothing, gray fur, and large eyes to compensate the darkness underground.

The evolution of the Morlocks to their biological and social functions are said to be a result of a widening split between different classes. The Morlocks are assumed to be of the working class of society while the Eloi belonged to the elite. As resources become scarce, the Morlocks, who have been used to labor, prove to be the stronger of the two classes.

The 2002 movie adaptation shows the Morlocks evolving into more of a hive society, with different castes performing different functions and an "Über-Morlock" as the central figure. Some castes are show to be at least partially quadrupedal. Instead of evolving from a working class they are instead descendants of those who took shelter underground following the destruction of the moon in 2037.

In the second timeline they are direct descendants of humans, though not of any particular class. They are shown as sexually amorphous, with infants being grown out of the substance of the Sphere and the dead being reabsorbed. The Morlock society in the second future is dedicated to the gathering of knowledge about the universe.

Language
The Morlocks are shown to have a language described as "liquid," but are (at least in the second variety) able to adapt to speaking English or other languages from history. No Morlock words are shown, but one Morlock name, Nebogipfel, is given for one of the species that accompanies the Time Traveler from 657,208 back to 1873.