Eloi represent an extension of the leisure class. His theories are further amended over the course of the novel, until (towards the end of his time in this future world) he has determined that the Morlocks have emerged as the masters of this future world, with the Eloi in a situation akin to herd animals which the Morlocks pray upon.

Again, it's important to note that all of these suppositions may well be false—the time traveler comes into this future universe from a position of utter ignorance, a fact which he himself is well aware of. Furthermore, consider that his reading of that future is deeply shaped by his perspective as a Victorian. However, if we take his interpretation as our departure point (as I suppose we must, given he is our only source of insight into this future world), what we observe is the final consequences of industrialization. Evolution has worked its power on both the working class and the leisure class, leaving each of them less than human.

Furthermore, note how the Morlocks terrorize the Eloi (representing a reversal of the power dynamics that shape the industrial class structure). If we understand that class structure as inherently exploitative, then we see in their relationship a situation by which the conditions of industrialization has shaped the future of human evolution, with all its brutality and cruelty is now imprinted directly upon the human condition.

H.G. Wells's novella The Time Machine is a classic in science fiction for its elaboration and codification of time travel tropes. When the time traveler reaches the far future, he meets two distinct species of human, the Eloi and the Morlocks.

Although be briefly supposes the Morlocks to be non-human, he quickly comes to the theory that Man has split along two evolutionary paths; the aristocratic intellectual elite remained on the surface, pursuing knowledge and art, before losing sight of their intellect and falling to sloth and simplicity -- these are the Eloi. Meanwhile, the workers who toiled in underground chambers, maintaining machinery and generally keeping things working, slowly lost their intelligence as well, but to a much greater degree; as the machines broke down, the underground men became more like animals, even turning to cannibalism -- these are the Morlocks. Both species are descended from 19th century Man, but the circumstances of their evolution has altered their biology and mental ability.

The Upper-world people might once have been the favoured aristocracy, and the Morlocks their mechanical servants: but that had long since passed away. The two species that had resulted from the evolution of man were sliding down towards, or had already arrived at, an altogether new relationship. The Eloi, like the Carlovingian kings, had decayed to a mere beautiful futility... and the Morlocks made their garments, I inferred, and maintained them in their habitual needs, perhaps through the survival of an old habit of service.
(Wells, The Time Machine, eNotes eText)

Additionally, as the quote shows, there is still some connection between the two species, even as the Morlocks move from unthinking servitude to predators.

Much British literature of the 1890s contained pessimistic and nihilistic attitudes. Wells' The Time Machinereflects the cultural and intellectual climate of the last Victorian decade (he  wrote the book in 1895), and is influenced by new discoveries in biology. Darwin's texts and T. H. Huxley's teaching showed that man's life-span is very short compared to geological time, and that man can actually be evolving downwards, like the ape-like Morlocks in the book. In 1892 Max Nordau published Degeneration,which Wells read.  Degeneration was an attack on the wealthy who did not work and the kind of art that lacked moral grounding.  It argued that the human species was degenerating as a result of its evolution—relying on technology, sharp class distinctions, and life without strong moral purpose.  These are the ideas that influenced Wells in creating the Morlocks and Eloi.  The purposeless good life of the Eloi (or wealthy upper classes and the art they produced) would eventually devolve into the Morlocks, who would, though underground and apparently “below” the Eloi, be the real class in power.

The Morlocks are believed to have developed from the working class of society. They were sent underground to operate and tend to the machines. As time passed, the Morlocks changed to adapt to their environment underground. They became smaller, extremely white-skinned, with large eyes. They're ape-like in their behavior and afraid of fire and light. They now have control over the Eloi because the Eloi depend upon them for everything in their lives. The Morlocks are carniverous and "harvest" the bodies of the Eloi for food.

The Eloi are thought to have devolved from the upper class, those who owned land. They are vegetarians and live above ground. As time passed, there was less and less work to do, so the Eloi became smaller and very frail, even though are a gentle group of beings. They are only about four feet tall and childlike in their behavior. It's ironic that they now depend upon the Morlocks for their very existence.

When the Time Traveller discovers the existence of the Morlocks, he believes that humanity has evolved into two distinct life forms after aeons of having two castes of humans: the haves and the have nots. The Morlocks, as the laboures in this scenario, have been distanced and kept separate from the Eloi, who he thinks are the aristocracy. The "widening gulf" that exists between the haves and the have nots, which the Time Traveller can find a disturbing parallel with in his own world, would have widened ever further as culture and customs keep them separate, until eventually you have two different species evolving:

So, in the end, above ground you must have the Haves, pursuing pleasure and comfort and beauty, and below ground the Have-nots, the workers getting continually adapted to the conditions of their labour.

The Time Traveller concludes that the Have-nots would then have to pay some sort of rent to the Haves as they would be in bondage to the Haves. It is of course in this that he is disturbingly mistaken, as the rest of the novel goes on to show and as he learns more about the Morlocks.

Having gone down into the lair of the Morlocks themselves, and made the interesting observation that the Morlocks were carnivores, the Time Traveller is struck by the horror of a conclusion that he avoids thinking through there and then. It is only later, when he considers the terror that the Eloi have of night and the way that they sleep together in huge huddles, and the way that the Morlocks are only able to go out of their subterranean dwellings at night that the full horror of the truth comes upon him. Note the following conclusion:

I tried to look at the thing in a scientific spirit. After all, they were less human and more remote than our cannibal ancestors of three or four thousand years ago. And the intelligence that would have made this state of things a torment had gone. Why should I trouble myself? These Eloi were mere fatted cattle, which the antlike Morlocks preserved and preyed upon--probably saw to the breeeding of. And there was Weena dancing at my side!

What is interesting about this quote is the way in which the Time Traveller tries to talk rationally about his conclusions, in a "scientific spirit." However, in spite of his attempts of attaining rationalism, what prevents him is the very real presence of Weena, an example of an Eloi, dancing there beside him in all of her beauty. The love that the Time Traveller has for Weena prevents him looking at this conclusion with anything else but the utmost abhorrence.

In The Time Machine, the dinner party is a key event which depicts class inequality. This event is directly referenced in Chapter 2 and Chapter 12 of the story and takes place at the Time Traveller's home. The dinner party demonstrates the wealth and privilege of the Victorian middle class in a number of ways.

Firstly, the guests at the dinner party represent some of the most respectable and well-paid professions in Victorian society: there is an editor, for example, a psychologist and a doctor. 

Secondly, in this "warm and comfortable" dining room, the guests enjoy a meal prepared by a cook and are served by the Time Traveller's "man-servant;" both representative of the working classes who here symbolise subservience and inferiority. 

After dinner, the guests then go the "smoking-room" where they have cigars and talk further on the subject of time travel. This room represents middle-class wealth and privilege; it is a room that is far removed from the poverty and deprivation of late-Victorian England. 

In Chapter Seven of The Time Machine, the Time Traveller makes a startling discovery about the Morlocks and the Eloi:

And for the first time, with a sudden shiver, came a clear knowledge of what the meat I had seen might be.

This is the critical realisation that the Morlocks hunt and eat their neighbours, the Eloi. This explains the "Great Fear" which the Eloi demonstrate whenever the Time Traveller tries to ask questions about who might have taken his time machine and who dwells in the darkness below. 

Based on his early observations, the Time Traveller believes that this society split into the Haves and Have-Nots at one time in the past:

So, in the end, above ground, you must have the Haves, pursuing pleasure and comfort and beauty, and below ground, the Have-Nots, the workers getting continually adapted to the conditions of their labour.

Eventually, the Morlocks ran out of food and looked to their neighbours above for a fresh source of meat:

The Eloi were mere fatted Cattle, which the ant-like Morlocks preserved and preyed upon.

The reader sees how the Morlocks have adapted to suit their hunting of the Eloi. They have "large, bright eyes," for example, which enable them to better see the Eloi in the darkness. They are expert climbers, described as a "human spider" by the Time Traveller (Chapter Five). Again, this agility is what helps them to hunt efficiently. Likewise, the Eloi have evolved in a manner which makes them easy prey: they are "fragile" and unintelligent, and exhibit a "childlike ease," says the Time Traveller in Chapter Four. Thus, the Morlocks and the Eloi have adapted to become the hunter and the hunted.