The bison looks back at its killer accusingly, its body flattened on the ground, its head twisted violently. Potently engraved on a piece of stone during the late ice age more than 12,000 years ago and discovered in 19th-century France, it is now on view in Prehistory: Objects of Power, a permanent display at the British Museum, a place to confront the astounding age of human culture.
The oldest artefacts in the exhibition, chopping tools from Tanzania, are almost two million years old. A hand axe found in Sussex in 1797 and recognised then as something very early is much more ancient than its discoverer could have imagined, living in an age when the biblical account of creation was just beginning to be doubted. It is thought to have been made 400,000 years ago.
As technology, these objects created by early humans are impressive. As works of art, they are daunting, mind-fuddling. Very early in the development of technology, something astonishing happens. Axe heads take on features that cannot be purely practical. Beautiful, glittering rock crystal is selected, then chipped into a symmetrical, visually satisfying shape. Although the British Museum's Prehistory display more or less avoids the word "art", it shows the difficulty of telling where use ends and aesthetic power begins in the earliest human cultures.
Early humanity is revealed here as living in a way that would have delighted the Victorian art critic John Ruskin, who longed for a unified culture: in the stone age, it seems, even the most practical knife or harpoon was at the same time a thing of magic, wonder and, for want of a better word, beauty. And then there is art to which we do not need to give any other name: drawings on stone such as the dead bison, animal portraits engraved on reindeer bones. Images, bold as life.
By the perspective of the world's oldest art, the entire period that is routinely encompassed by "the history of art" from the Renaissance to today is just the blink of an eye; Da Vinci, Rembrandt, Goya and Koons belong to a tiny sliver of time.
And yet, when the antiquity of art was realised for the first time in the late 19th century, it did not oppress artists with the weight of past centuries. On the contrary, it was a liberation from a history that had become stale and burdensome. Prehistoric art is modern art's alternative tradition. It is so old that it is not experienced as old - it exists outside any history we can write. The cult of the new that is modern art was inspired by the spectacle of the very, very ancient. Stone age art in the form of portable objects and on cave walls was alien, enigmatic, fresh in a way the Renaissance no longer was.
Modern art manifestos are full of denunciations of the Renaissance. "I prefer the most minor [modernists]", declared Matisse in 1908, "to all of those who are content to imitate the Venus of Urbino or the Madonna of the Goldfinch." Contrast this with the way the artist and critic Amédée Ozenfant hails the discovery of the cave-paintings at Les Eyzies in France in his 1928 book Foundations of Modern Art: "Ah, those hands! Those silhouettes of hands, spread out and stencilled on an ochre ground! Go and see them. I promise you the most intense emotion you have ever experienced."
Modern art rejected the sophistication of the past five centuries of painting and sculpture, the pursuit of realistic effects and classical beauty, and instead identified with the art just beginning to be rediscovered in caves in the late 19th century. Abstraction, unadorned drawing, non-representational colour, superimposition: all the values of modern art had their primal scene in the caves.
Stone age art is often bundled together with the non-European art collected and imitated by modern artists in Paris at the turn of the century as one more aspect of the "primitivism" flaunted by paintings such as Picasso's Les Demoiselles d'Avignon (1907). But this has blinded us to the specific nature of modern art's encounter with early humanity. Cave painting was discovered and recognised at exactly the same time as modern art was born - palaeolithic and modern artists had their debuts and caused commotions at the same art fairs, the same 19th-century world exhibitions. Forget, for a moment, the primitivism of modern art, and consider its relationship to the discovery of deep cultural time.
Engraved pieces of reindeer bone and ivory from palaeolithic caves were first collected in the early 19th century, but it was not until the 1860s (contemporaneously with Manet's paintings) that archaeologists agreed that the objects being found in ever-greater quantities were extraordinarily old, that they dated from 35,000 to 8,000 years ago (for comparison, the Great Pyramid at Giza is less than 5,000 years old; Pompeii was buried just under 2,000 years ago). Fifty-one examples of palaeolithic art were shown at the Paris Exposition Universelle in 1867. Manet, rejected by the same exhibition, held his own retrospective nearby and painted a panoramic cityscape, Exposition Universelle de 1867, a founding work of impressionism.
In the following year a Spanish hunter's dog got caught in some rocks, and in freeing him his owner discovered a previously unknown cave. The cave at Altamira, in northern Spain, contained very old paintings, and was excavated systematically in 1879 by Sanz de Sautuola, a gentleman scholar who had seen palaeolithic art objects in Paris. "Look, Papa - oxen!", exclaimed his young daughter, looking up at the roof. Despite passionate research by De Sautuola, it was not until the early 1900s that the authenticity of the paintings at Altamira was accepted - French scholars accused their discoverer of either fraud or being taken in by peasants.
In the 1880s and 90s engraved and painted images were found in several caves in France, and the evidence began to convince sceptics. In 1901 paintings were discovered in a cave near Les Eyzies in the Dordogne. Cave painting had arrived. Les Eyzies became the site of the best-known cave art until the accidental discovery of Lascaux in the 1940s and, most recently, Chauvet.
Art of this age is not unique to Europe, let alone France: cave paintings in Australia, the Americas and Africa go back 10,000 to 30,000 years. But it was in France (and Spain) that this art was first widely known, at the moment when Paris saw the heroic experiments of modern art. In 1905 Paris was shocked by the ferocious, crude art of Matisse and his fellow fauves - "wild beasts", as a hostile critic called them.
According to the art historian John Richardson, the sources on which Matisse drew in his most programmatic fauve painting, Le Bonheur de Vivre (1905-6), included drawings of cave paintings by the Abbé Henri Breuil. Born in 1877, Breuil was a seminal figure in documenting and popularising cave art. He was skilled at tracing figures in caves, including at Altamira. He was also a theorist of the origins of art who believed that cave paintings were a form of sympathetic magic. His drawing style is, interestingly, bold and heavy in line - in a way that makes you think of Picasso - popularising an image of cave art as starkly figurative.
Palaeolithic art seemed, to modern observers, preoccupied with animals, with an urgent need to depict bison, mammoths, reindeer. To experts such as Breuil it seemed there must be more than an aesthetic pleasure in painting animals. They theorised that the paintings deep inside caves must have an occult purpose, magically empowering the hunter. Animals appear being hunted, with lines cutting their sides, interpreted as spears. Not only cave paintings: the two images of bison at the British Museum have spear-like lines across their stone flanks, and one may have blood coming out of its mouth. This is so close to the violence, rawness, primal energy of modern art. Isolated, energetic figures of animals appear in Rousseau, Picasso, Ernst; animals figure in a primitivist, totemic way in the German expressionist paintings of Franz Marc and the hermetic art of Paul Klee.
And yet influence is a tricky idea. As much as shaping modern art, you could argue that prehistoric art was shaped by it - that without a radical disturbance of ideas of what art is, stone age art would never have been recognised as art at all. It had lain there in caves, not necessarily impenetrable caves either, for millennia. There are scattered references to painted caves going back to the Renaissance - but they were dismissed as graffiti. According to the aesthetic values that dominated European high culture in the 15th to 19th centuries, the flat, forcefully drawn, overlapping shapes in caves could not be art, or could only be the childish art of the untrained. They were not accomplished.
"In the work of the school we are now considering, we find a harshness in the juxtaposition of tints, a crudeness of local colouring, a heaviness of hand, what seems a studied avoidance of delicate workmanship, and in short, what in France would be called a franchise naïve et brutale [a naive and brutal freedom]", wrote an English critic of the impressionists in 1874. This language of disruption, brutality, primitive coarseness would be levelled at every modern art movement in turn. And the shattering of aesthetic rules must have made the images that began to be noticed in caves at this time recognisable, intriguing. If Monet was a painter, perhaps so were the early humans of 12,000 years ago.
Western art in the mid-19th century saw itself as the latest chapter in an unbroken story, from the Greek and Roman world via the Renaissance. The discovery of stone age art, contemporary with a new availability of examples of tribal and "primitive" art in an age of empire, offered a way out of this closed history. There is no way of connecting stone age art to ourselves through narrative - only by analogy.
This art is not only prehistoric; it is anti-historic. In modern art this was figured as a primal, irrational human need to create, to splash out wildly, painting in the dark. In 1948 Jackson Pollock re-enacted the making of hand prints and hand stencils deep inside caves by people 12,000 years ago by leaving hand prints along the top edge of his painting Number 1A, 194 8. If prehistoric art did not exist, modern art would have had to invent it.
· Prehistory: Objects of Power is at the British Museum, London WC1 (020-7323 8000).