At the heart of this spellbinding book is a simple but chilling idea: human nature will be transformed in the 21st century because intelligence is uncoupling from consciousness. We are not going to build machines any time soon that have feelings like we have feelings: that’s consciousness. Robots won’t be falling in love with each other (which doesn’t mean we are incapable of falling in love with robots). But we have already built machines – vast data-processing networks – that can know our feelings better than we know them ourselves: that’s intelligence. Google – the search engine, not the company – doesn’t have beliefs and desires of its own. It doesn’t care what we search for and it won’t feel hurt by our behaviour. But it can process our behaviour to know what we want before we know it ourselves. That fact has the potential to change what it means to be human.

Yuval Noah Harari’s previous book, the global bestseller Sapiens, laid out the last 75,000 years of human history to remind us that there is nothing special or essential about who we are. We are an accident. Homo sapiens is just one possible way of being human, an evolutionary contingency like every other creature on the planet. That book ended with the thought that the story of homo sapiens could be coming to an end. We are at the height of our power but we may also have reached its limit. Homo Deus makes good on this thought to explain how our unparalleled ability to control the world around us is turning us into something new.

The evidence of our power is everywhere: we have not simply conquered nature but have also begun to defeat humanity’s own worst enemies. War is increasingly obsolete; famine is rare; disease is on the retreat around the world. We have achieved these triumphs by building ever more complex networks that treat human beings as units of information. Evolutionary science teaches us that, in one sense, we are nothing but data-processing machines: we too are algorithms. By manipulating the data we can exercise mastery over our fate. The trouble is that other algorithms – the ones that we have built – can do it far more efficiently than we can. That’s what Harari means by the “uncoupling” of intelligence and consciousness. The project of modernity was built on the idea that individual human beings are the source of meaning as well as power. We are meant to be the ones who decide what happens to us: as voters, as consumers, as lovers. But that’s not true any more. We are what gives networks their power: they use our ideas of meaning to determine what will happen to us.

Not all of this is new. The modern state, which has been around for about 400 years, is really just another data-processing machine. The philosopher Thomas Hobbes, writing in 1651, called it an “automaton” (or what we would call a robot). Its robotic quality is the source of its power and also its heartlessness: states don’t have a conscience, which is what allows them sometimes to do the most fearful things. What’s changed is that there are now processing machines that are far more efficient than states: as Harari points out, governments find it almost impossible to keep up with the pace of technological advance. It has also become much harder to sustain the belief – shared by Hobbes – that behind every state there are real flesh-and-blood human beings. The modern insistence on the autonomy of the individual goes along with a view that it should be possible to find the heart of this heartless world. Keep scratching at a faceless bureaucracy and you’ll eventually uncover a civil servant with real feelings. But keep scratching at a search engine and all you’ll find are data points.

We are just at the start of this process of data-driven transformation and Harari says there is little we can do to stop it. Homo Deus is an “end of history” book, but not in the crude sense that he believes things have come to a stop. Rather the opposite: things are moving so fast that it’s impossible to imagine what the future might hold. In 1800 it was possible to think meaningfully about what the world of 1900 would be like and how we might fit in. That’s history: a sequence of events in which human beings play the leading part. But the world of 2100 is at present almost unimaginable. We have no idea where we’ll fit in, if at all. We may have built a world that has no place for us.

Given what an alarming thought this is, and since we aren’t there yet, why can’t we do more to stop it from happening? Harari thinks the modern belief that individuals are in charge of their fate was never much more than a leap of faith. Real power always resided with networks. Individual human beings are relatively powerless creatures, no match for lions or bears. It’s what they can do as groups that has enabled them to take over the planet. These groupings – corporations, religions, states – are now part of a vast network of interconnected information flows. Finding points of resistance, where smaller units can stand up to the waves of information washing around the globe, is becoming harder all the time.

Some people have given up the fight. In place of the founding tenets of modernity – liberalism, democracy and personal autonomy – there is a new religion: Dataism. Its followers – many of whom reside in the Bay Area of California – put their faith in information by encouraging us to see it as the only true source of value. We are what we contribute to data processing. There is potentially a huge upside to this: it means we will face fewer and fewer obstacles to getting what we want, because the information needed to supply us will be instantly accessible. Our likes and our experiences will merge. Our lifespans could also be hugely extended: Dataists believe that immortality is the next frontier to be crossed. But the downside is obvious, too. Who will “we” be any more? Nothing more than an accumulation of information points. Twentieth-century political dystopias sought to stamp on individuals with the power of the state. That won’t be necessary in the coming century. As Harari says: “The individual will not be crushed by Big Brother; it will disintegrate from within.”

Corporations and governments will continue to pay homage to our individuality and unique needs, but in order to service them they will need to “break us up into biochemical subsystems”, all of them permanently monitored by powerful algorithms. There is a dystopian political aspect to this, too: the early adopters – the individuals who sign up first to the Dataist project – will be the only ones with any real power left and it will be relatively unchallenged. Gaining entry into this new super-elite will be incredibly hard. You’ll need heroic levels of education plus zero squeamishness about marrying your personal identity with intelligent machines. Then you can become one of the new “gods”. It’s a grim prospect: a small priestly caste of seers with access to the ultimate source of knowledge, and the rest of humanity simply tools in their vast schemes. The future could be a digitally supercharged version of the distant past: ancient Egypt multiplied by the power of Facebook.

Harari is careful not to predict that these outlandish visions will come to pass. The future is unknowable, after all. He reserves his strongest opinions for what all this should mean for the current state of relations between humans and animals. If intelligence and consciousness are coming apart then this puts most human beings in the same situation as other animals: capable of suffering at the hands of the possessors of superior intelligence. Harari does not seem too worried about the prospect of robots treating us like we treat flies, with violent indifference. Rather, he wants us to think about how we are treating animals in our vast industrialised farming systems. Pigs unquestionably suffer when living in cramped conditions or forcibly separated from their young. If we think this suffering doesn’t count because it is not allied to a higher intelligence, then we are building a rod for our own backs. Soon the same will be true of us. And what price our suffering then?

This is a very intelligent book, full of sharp insights and mordant wit. But as Harari would probably be the first to admit, it’s only intelligent by human standards, which are nothing special. By the standards of the smartest machines it’s woolly and speculative. The datasets are pretty limited. Its real power comes from the sense of a distinctive consciousness behind it. It is a quirky and cool book, with a sliver of ice at its heart. Harari cares about the fate of animals in a human world but he writes about the prospects for homo sapiens in a data-driven world with a lofty insouciance. I have to admit I found this deeply appealing, but that may be because of who I am (apart from anything else, a man). Not everyone will find it so. But it is hard to imagine anyone could read this book without getting an occasional, vertiginous thrill. Nietzsche once wrote that humanity is about to set sail on an open sea, now that we have finally left Christian morality behind. Homo Deus makes it feel as if we are standing at the edge of a cliff after a long and arduous journey. The journey doesn’t seem so important any more. We are about to step into thin air.

• Homo Deus: A Brief History of Tomorrow is published by Harvill Secker. To order a copy for £20.50 (RRP £25) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.