For the want of a nail, a shoe was lost; for the want of a shoe, the horse was lost; for the want of a horse, the rider was lost; for the want of a king, the battle was lost . . .
Tiny changes can make huge differences. No method known to science, even in principle, can predict the emergence of such structures as cyclones, blizzards, and hurricanes from the molecular motions of the atmosphere. All animals grow from proteins, but biochemistry can say nothing about the forms that evolution will shape into species. One of the inevitable products of increasing complexity is greater unpredictability.
Hence arises the increasing variability of behavior that comes with progressively higher levels of neural development. Insects and other comparatively simple organisms react to their environments with genetically determined response patterns so unvarying that individuals are indistinguishable, and researchers have no hesitation in declaring that when this species is exposed to that stimulus, it will respond in such and such a particular way. Farther up the evolutionary tree—"up," of course, being defined as that direction in the radiating bush that points from the common origin to the part of the periphery occupied by ourselves—things become less determinate as individual traits begin to emerge, until at the level of our household pets we discern distinct personalities. The ultimate, for the present, is reached with fully intelligent, sapient beings, where anything goes and nothing that anyone is capable of thinking, wanting, liking, or doing should come as any great surprise anymore.
Variability means faster adaptability to change, which is what evolution is all about. Species that invite the mirth of amoebas and cockroaches by adopting neural development as their survival strategy achieve adaptability by supplementing genetic programming with acquired learning. With advancement, proportionately less of the total information passed from generation to generation comes as molecular coding—which is slow to change, slow to be refined through selection, and slow to diffuse through a population—and more of it as culturally transmitted knowledge in all its guises—which isn't. Discoveries made by a single genius can spread virtually instantaneously; the learning of an age is passed on intact to be built upon further. The result is a thermal runaway of ideas and techniques that rapidly culminates in the explosion of even higher-level organization and energy capture known as technological, industrial—followed almost immediately by spacegoing—civilization.
But as with every other innovation in a process whose roots twist back into veils of mystery billions of years ago, this step, too, brings its drawbacks. One of them is the wastefulness of the effort that individuals must expend in acquiring even a fraction of that information and laboriously building up the private collections of beliefs and experiences, hopes and memories, achievements and dreams that constitute the sum total to show for a lifetime . . . only to have most of it lost with them when they go. Learning is such hard work compared to the effortless way in which the genetic endowment is inherited and the equally simple—and, furthermore, quite enjoyable—procedure for passing it on.
The drawback, in a word, is mortality.
Throughout history the thought has troubled and depressed those who thought too much about it, at times driving them to suicide. And it was also a source of concern to some among a race called the Borijans, descended from a species of large, flightless squabblesome bird, who were part of a general pattern of six-limbed, laterally symmetrical life-forms inhabiting a planet called Turle, a thousand light-years from our solar system, over a million years before humankind existed to share its worries about such matters.