Yuval Noah Harari is an Israeli historian who had a best-seller with Sapiens: A brief history of humankind (2014; both books appeared originally in Hebrew, 2011 and 2014).   This follow-up, Homo Deus, suggests what the future may hold for our species; may, not will: Harari is not a prophet, though one has a passing thought of the Old Testament figure with whom he shares his middle name, inasmuch as he considers the possible fate of the human race.

This follows on from the earlier book, which is partly recapitulated. As I paraphrase it, Harari distinguishes the following main stages of development of Homo sapiens, marked by “revolutions”:  cognitive, above all the creation of language; agricultural, with greatly accelerated demographic growth and larger social organizations; urban (from about 5000 years ago), with writing and money, eventually cities and nations; scientific (from about 500 years ago), methods of empirical science applied to ever more phenomena; humanist (18th century Enlightenment), with a new emphasis on individual experience, rejection of supernatural authority, and latterly global communication.

These are not cut-off points; while no human groups now lack language, a dwindling few remain essentially pre-agricultural hunter-gatherers; and it is only in the present century that city-dwellers have become the majority of the human race.   Similarly, the humanist revolution replaced deities as the final source of authority with human experience and thought, but though God is dead, as Nietzsche announced, in large parts of the world he shows little sign of lying down.

Perhaps confusingly, Harari uses the word “religion” very widely, to refer to prevailing systems of thought and belief, thus humanism is for him a religion, though many who regard themselves as humanists would see it as including a rejection of religion. In any case, Harari argues that this too will be, and indeed is already being, superseded. We humans, assuming god-like authority,  dominate our world, to the extent that a “natural” environment no longer exists.

The vast majority of other large species survive only insofar as they serve our needs; domesticated creatures such as battery hens and sows in gestation crates are scarcely more than bits of living machinery. We have effectively ended as universally omnipresent the three great ancient threats to our existence, famine, disease and war. But our colossal and very recent scientific and technological advances are creating unforeseen threats. Of course this idea in principle has been a commonplace of science fiction at least since Victor Frankenstein gave life to his home-made creature. But that was fantasy; today’s robots are real. Arnold Schwarzenegger’s “Terminator” soon could be.

Harari suggests that from a distant perspective Homo sapiens might be looked at as a data processing system, with individuals in the role of chips. Our history would then appear as the process of improving the system by four basic methods: increase the use of the processors (via larger group sizes); increase ease of communication between processors (language); increase the number of connections between processors (travel and communication); increase ease of transmission along existing connections (safe and rapid travel, speed of communication).

What will come next? Harari suggests a new and ever more efficient data processing system. For some time computers have far excelled their makers in computation, and machines will soon produce vastly more data than humans, whether individuals or organisations including traditional political structures, can handle fast enough to produce meaningful policies.  There will be, argues Harari, a power vacuum. New and more efficient systems (or “religions”) will emerge to fill it, possibly not essentially human.

The future, he argues, is overshadowed by three interlinked processes. One is that science is converging on an all-encompassing dogma: that organisms are algorithms and life is data processing (algorithm: a procedure or set of rules to be followed, here, for processing information). Second, intelligence is decoupling from consciousness. And third, non-conscious but highly intelligent algorithms may soon know us better than we know ourselves (you may forget what websites you browse, but your PC does not, let alone the truly world wide web of which it is part).

There seem to be two possibilities for new “techno-religions”, Harari says. One way lies in producing technologically advanced humans, who might closely resemble the gods of polytheistic religions (eg of classical Greece). Those deities were believed to enjoy not omnipotence but rather specific super-powers such as the ability to design and create living beings, to transform their own bodies, to control the environment and the weather, to read minds and communicate at a distance, to travel at very high speeds, and to escape death and live indefinitely. We can already, or will soon, do all of these (the last by regular systematic replacement of parts). Such superbeings might be only the few who could afford the technology, with the rest reduced to the status of cattle, or pets.

The other possibility is a “religion” of Dataism, in which the supreme value lies in freedom of information (not of expression, which is part of the old Humanist religion). Humans would appear as imperfect information processors, likely to be superseded by machines as the horse was by the internal combustion engine; as the human brain (necktop, Harari neatly calls it) is already surpassed by a desktop PC. What then of what we like to consider our trump cards, so to speak, such as subjective experience, consciousness and free will? They are simply unnecessary illusions: the PC needs no monitor to function, and what appears on a screen is not the workings inside. Programmes can beat human champions at chess and go:  intelligence without consciousness. The future would lie with an ever more powerful information processor, embracing at last the whole of creation, and becoming in effect God.

From the point of view of an atheist, freethinker or secularist, if either of these scenarios is close upon us, we too will be redundant. And one cannot be unaware of, on the one hand, a sharp and accelerating decline in religious belief, and on the other the even more dramatic advances of technology: both at least in our Western societies. At the moment of writing the latest British Social Attitudes Survey reports 53 percent of the population claiming they have no religion (from 31 percent in 1983; a majority for the first time). Children in perambulators carry mobile phones with which they can, in principle, speak around the globe. The first mobile is dated to 1973; some of those children’s parents were not born.

On the other hand, we may feel that the old God religions still have far too much, often malign, influence in human affairs, and there is still much to work for. We may feel that we humans, faulty though we are, still have qualities that are worth preserving and developing, even if ultimately our only justification is that they are in fact ours. Homo Deus can be criticised by historians as sometimes slap-happy or even plain wrong, philosophers may query its views on such matters as consciousness and free will, and psychologists on personality, emotions and much more; and it is no doubt simply ruled out of court by theologians for its attitude to God and gods. All these are matters of legitimate debate.  Still to my mind it has the great merits of being readable, informative and intellectually highly stimulating. It makes you think.

John Radford is Emeritus Professor of Psychology, University of East London