Last and First Men - Human Species

Human Species

• First Men. (Chapters 1–6) Our own species: the rivalry of America and China, the First World State, its destruction as a result of using up all natural resources, followed by the Patagonian Civilization 100,000 years hence, with the cult of Youth, and its destruction after the sabotage of a mine which leads to a colossal subterranean atomic explosion and the ensuing intercontinental nuclear holocaust, rendering most of the Earth's surface uninhabitable for millions of years save for the poles and the northern coast of Siberia. The only survivors are thirty-five humans stationed at the North Pole, who eventually split up into two separate species, the Second Men and some sub-humans.
• Second Men. (Chapters 7– 9) "Their heads, indeed, were large even for their bodies, and their necks massive. Their hands were huge, but finely moulded...their legs were stouter...their feet had lost their separate toes...blonde hirsute appearance...Their eyes were large, and often jade green, their features firm as carved granite, yet mobile and lucent. ...not till they were fifty did they reach maturity. At about 190 their powers began to fail..."
• Third Men. (Chapter 10) "Scarcely more than half the stature of their predecessors, these beings were proportionally slight and lithe. Their skin was of a sunny brown, covered with a luminous halo of red-gold hairs... golden eyes... faces were compact as a cat's muzzle, their lips full, but subtle at the corners. Their ears, objects of personal pride and of sexual admiration, were extremely variable both in individuals and in races. ... But the most distinctive feature of the Third Men was their great lean hands, on which were six versatile fingers, six antennae of living steel." Deeply interested in music and in the design of living organisms.
• Fourth Men. (Chapter 11) Giant brains, built by the Third Men. For a long time they help govern their creators, but eventually come into conflict.
• Fifth Men. (Chapters 11–12) An artificial human species designed by the brains. "On the average they were more than twice as tall as the First Men, and much taller than the Second Men... the delicate sixth finger had been induced to divide its tip into two Lilliputian fingers and a corresponding thumb. The contours of the limbs were sharply visible, for the body bore no hair, save for a close, thick skull-cap which, in the original stock, was of ruddy brown. The well-marked eyebrows, when drawn down, shaded the sensitive eyes from the sun." When Earth ceases to be habitable, they terraform Venus, but do not cope well after the move.
• Sixth Men. (Chapter 13) "Sadly reduced in stature and in brain, these abject beings... gained a precarious livelihood by grubbing roots upon the forest-clad islands, trapping the innumerable birds, and catching fish... Not infrequently they devoured, or were devoured by, their seal-like relatives."
• Seventh Men. Flying humans, "scarcely heavier than the largest of terrestrial flying birds", are created by the Sixth Men.
• Eighth Men. "These long-headed and substantial folk were designed to be strictly pedestrian, physically and mentally." When Venus becomes uninhabitable, they design the Ninth Men, who will live on Neptune.
• Ninth Men. (Chapter 14) "Inevitably it was a dwarf type, limited in size by the necessity of resisting an excessive gravitation... too delicately organized to withstand the ferocity of natural forces on Neptune... civilization crumbled into savagery."
• Tenth to Seventeenth Men. "Nowhere did the typical human form survive." Sentience re-emerges from animals on multiple occasions. The Fifteenth and Sixteenth achieve a great civilization and learn to study past minds. (These species are essentially Neptunian versions of the First and Second Men, respectively.) It is not until the Sixteenth Men, the first of the Neptunian artificial species, that the inevitable and deplorable cycle of rise and collapse of civilization is finally ended, and steady progress takes its place. The Sixteenth Men, frustrated by their inability to improve their civilization, decide that their nature is insufficiently advanced to produce a truly perfect community, and create an artificial species, the Seventeenth Men, to succeed them; however, the Seventeenth Men are "flawed" in some unspecified way, unimagined by the 16th due to their lesser awareness, and last only a short period of time before being replaced by the Eighteenth Men, essentially a more perfect version of their own species.
• Eighteenth Men. (Chapters 15–16) The most advanced humans of all. "Superficially we seem to be not one species but many." (One interesting aspect of the Eighteenth Men is that they have a number of different "sub-genders," variants on the basic male and female pattern, with distinctive temperaments. The Eighteenth Men's equivalent of the family unit includes one of each of these sub-genders and is the basis of their society. The units have the ability to act as a group mind, which eventually leads to the establishment of a single group mind uniting the entire species.) Despite their hyper-advanced civilization, they practice ritual cannibalism. They are eventually extinguished on Neptune after a supernova consumes the remains of the solar system.