had a wide range of other interests including politics, biology and archaeology. His interest in the natural world grew from his friendship with Charles Darwin, who moved to the same village, Downe, in Kent, in 1842 when Lubbock was eight years old. As Lubbock matured, his interest in evolution and archaeology grew. He became an ardent supporter of Darwin’s evolutionary theories and of academic liberalism in general. He bought land in Wiltshire to save the famous prehistoric stone circle at Avebury from destruction and introduced into Parliament a bill that would eventually become the Ancient Monuments Act, the forerunner of all legislation to protect ancient sites.
Lubbock divided the Stone Age into two phases, the Palaeolithic, sometimes known as the Old Stone Age, lasting until roughly 10,000 years ago, and the Neolithic, the New Stone Age which followed it, coinciding with the invention of agriculture. Later an intermediate phase, the Mesolithic or Middle Stone Age, was adopted as the term for the period between the end of the last Ice Age about 17,000 years BP and the dawn of agriculture when the Neolithic began. About 4,000 years ago, the Neolithic gave way to the Bronze and then Iron Ages. The Palaeolithic was further divided into Lower, Middle and Upper phases, with the last of these lasting from about 50,000 years BP until the transition to the Mesolithic. Incidentally, the dates here only apply to the Stone Age in Europe. In other parts of the world the transitions occurred more recently; indeed, in highland New Guinea the Stone Age lasted until well into the twentieth century.
The genetic dating places the wolf–dog transition firmly within the Upper Palaeolithic, a quite extraordinary period in the history of our species, bristling with innovation and new ideas. The hallmark of the Upper Palaeolithic is the appearance of new forms of stone tools, the most durable of evidence. Until then, the only tools were hand axes and spear points. They were carefully made, certainly, but had not changed in basic design for tens of thousands of years. Suddenly, archaeologists were finding delicate arrow points, bone needles, even fish hooks, artefacts never seen in older, deeper layers.
Human fossils were much scarcer than stone tools, but they too showed a change from heavy-boned and robust skeletons whose skulls boasted prominent brow-ridges and receding chins to an altogether lighter and more graceful form. Was this a change brought about by slow adaptation, or was it the sign of the arrival in Europe of a new human species? After years of debate the argument was settled in favour of the wholesale replacement of the indigenous humans – Homo neanderthalensis, the Neanderthals – by a new arrival from Africa. This was Homo sapiens, our own ancestors. Mitochondrial genetics was the deciding factor in settling the argument in favour of replacement.
A few days before Christmas 1994 three speliologists, Eliette Brunel-Deschamps, Christian Heller and Jean-Marie Chauvet, were clambering over the face of the Ardèche gorge in southern France. Here the river cuts through the southern flanks of the limestone Massif Central on its way to join the Rhône near St-Just, well on its way to the Mediterranean. It is in the nature of limestone to form underground cave systems when exposed to the constant attention of slightly acidic groundwater. Over thousands of years the water gradually erodes the rock, hollowing out caverns of sometimes immense proportions.
The entrances to some 4,000 caves, many little more than overhangs, some as vast as medieval cathedrals, punctuate the steep walls of the gorge. Most are clearly visible, while others are hidden by rock-falls and vegetation. It was in order to find these hidden caverns that Jean-Marie Chauvet and his companions were inching their way along the steep sides of the gorge. They were searching for air currents emerging through cracks and crevices that would betray the presence of a cave system deep underground. At one point Chauvet felt a slight breeze coming from the rocks brushing the hairs on the back of his hands. He bent down to sniff the subterranean zephyr, then called his companions over. They agreed that the gentle flow smelled promisingly, damp, ancient and strangely alive. One by one they carefully removed the small rocks surrounding the vent until they came to a narrow cleft through which the air was escaping. It was too narrow for any of them to squeeze through, so next day they returned with hammers and a small pneumatic drill and set to work widening the crack. They found themselves faced with a narrow shaft descending into the black depths. Being experienced, not to say fearless, potholers they squeezed through the gap until they reached a point where a gallery opened out in front of them. It was clear, only from inside, that the main cave entrance had been blocked by an ancient rock-fall and that they had somehow found their way into the main cavern through the roof.*
As they explored the cave system over the following days the true wonder of their discovery began to dawn on them. Gleaming stalagmites rose up from the cave floor to meet their counterparts, delicate stalactites, suspended from the roof. Formed by the steady drip-drip-drip of calcium-rich water, their pristine condition showed that no animal or human had disturbed these hidden depths for thousands of years. On the floor lay scattered bones and skulls of cave bears petrified beneath a glassy coating of calcite.
This image actually comes from an exact replica of Chauvet cave that opened in Vallon-Pont-d’Arc in 2012, as access to the ancient caves is severely restricted for the protection of the artwork. The replica art was created using the same tools and methods as it is believed were used by the original artists. (Getty/AFP/Staff)
As Chauvet and his companions pushed further and further back along the galleries they saw in front of them the first of the paintings. Dozens of crude human hand prints outlined in red ochre covered one of the walls to a height of nearly two metres. These were only an introduction to the treasures which lay further back. There, on the deliberately smoothed cave walls, were drawn the images of lions, bears, mammoths, rhinoceros, horses and giant deer. These are the oldest morphologically accurate depictions anywhere in the world. What strikes home about them is their beauty. These are not merely crude outlines like the hand prints in the antechamber. They have form, expression and movement.
A painting from Chauvet cave that shows the head and horns of two aurochs, an extinct form of wild cattle that would have been a key prey animal for both humans and wolves. (JAVIER TRUEBA/MSF/SCIENCE PHOTO LIBRARY)
As well as being objects of wonder in themselves, these paintings have naturally led us to contemplate the reason they were drawn in the first place. What a task it must have been. Working deep underground without any natural light, the artists, for that is what they were, could only illuminate their lithic canvases by the light of glowing wooden torches. Streaks on the walls show where they had rubbed the dying embers to rejuvenate the flames. Carbon-dating the charcoal smeared on the walls was the means of discovering how long ago the drawings were made.
All organic material contains carbon, and this can exist in two forms called isotopes. Carbon 14 is very slightly radioactive. The other isotope, carbon 12, is not. After an animal or plant dies, or is burned in the case of the wooden torches, the radioactive carbon 14 slowly decays with a half-life of almost 5,000 years. In other words after 5,000 years there is only half as much carbon 14 remaining. By comparing the content of the two isotopes using a mass spectrometer to count the atoms, the age of the specimen can be estimated. Atmospheric carbon 14 is generated by ionising radiation from the sun high up in the atmosphere, some 32 kilometres above the ground. The proportions of the two carbon isotopes in the atmosphere are more or less in equilibrium. Thus the ratio of the carbon isotopes in a freshly dead animal or plant is equal to the atmospheric ratio at the time.
There are many factors that can change this ratio artificially and consequently introduce errors in dating. One is contamination of old material with modern carbon, for example from the archaeologists who recovered the specimen. This tends to make the material appear younger than it actually is. As is well known, carbon dioxide levels in the atmosphere have rocketed due to human activity since the Industrial Revolution. This carbon is ancient, coming as it does from the burning of fossil
