Could the reason that there are no elderly Eloi be that those Eloi who are not eaten become Morlocks, no longer able to gain sustenance except through eating their young who retain the ability to process plant matter? It'd prefigure the Babyeaters from Three Worlds Collide.
- Someone on another forum pointed out a few problems with this interpretation. First, there'd have to be some change to the baby schema in the Morlock brain to recognize young Eloi the way we recognize lambs, not the way we recognize human children. Nor does the text clearly establish that Morlocks know enough science to reestablish an Eloi ranch lost to natural disaster or overharvesting. And if the Time Traveller defeats them so easily using a blunt object and the light of a forest fire, they might not have the physical fitness to find another ranch.
- Alternately, the Morlocks were never eating Eloi at all; they were pragmatically eating other Morlocks that died of natural causes. The true life cycle of future-humanity is: young Eloi, brought underground, adult Morlock, funeral dinner. The Time Traveller jumped to the wrong conclusion because the two life-stages of the species don't look all that different once they've been reduced to meat and bones, and the TT is a physicist rather than an anatomist.
He was right. The creation of these two species followed an apocalyptic disaster turning the earths biome upside down. Plants were either unaffected or recovered but the animal populations never did. The surviving humans subsisted off of stored food until it ran out. When it inevitably did, they were faced with two choices: (a) adopt a protein-poor vegan diet or (b) engage in cannibalism. Those that took option A gradually evolved into the Eloi; their protein-starved bodies causing them to lose stature, their brains to shrink and they became herbivorous. Those that took option B gradually evolved into the Morlocks; as they became more and more carnivorous, their bodies adapted so that they were better hunters.
- The "apocalyptic disaster" could just be "the march of human progress" as it was understood in Wells' time. If you read predictions about the world of the future made by people around 1900, they almost always talk about entire lineages of animals being exterminated by humanity, sometimes for no other reason than "because we don't need them anymore". And this isn't presented as a bad thing, just an obvious consequence. Ecologism and wildlife conservation (outside of hunting reserves - maybe) wasn't even a concept in the industrialization era.
Basically, they seems to react on the Time Traveller exactly as humans would react on a ten-foot giant that suddenly appeared from nowhere on the cattle ranch and start to cause all kind of troubles to the owners.