When prehistoric cultural developments in the Old and New World are compared, one difference is outstanding. The American Indian domesticated an inordinately large number of plants. This is even more remarkable when one considers that the prehistoric population of the Americas was very much less than that of the Old World and, also, that the development of American civilization began very much later.

During the last 25 years, archaeological investigations in the New World have revealed considerable information about prehistoric plant domestication and agriculture. Although this data is far from complete, it is now possible to establish some hypotheses, not only about the origin and spread of several American domesticates, but also about the effect of plant domestication, and later agriculture, upon cultural development and process in the New World.

In June 1964 some prehistoric rock-engravings of great interest and skilful execution were discovered in the Cyrenaican Gebel. They are the first works of rock-cut art of early prehistoric style found in this region after more than 30 years of research and survey carried out by Italian and English scholars in the field of prehistoric archaeology. In 1959 I had the opportunity of visiting several caves and shelters on the very steep rock walls of the widiàn notching the Gebel, and on the two big escarpments of this plateau facing north towards the Mediterranean. In none of the cavities thus explored have I found prehistoric art, except in a single case—of no absolute certainty—consisting of some line-engravings.

In the spring of 1964 I was informed of the existence of some rock-drawings of animals in a cave not far from Cyrene, and some weeks later I went to this site. No doubts about the authenticity of these engravings can be entertained, since, as we shall see, some of them are partially covered with stalactitic concretions.

Some years ago, in a short review of some of the major questions concerning agricultural efficiency in Roman times, I pointed out that we do not possess the materials on which to base an accurate computation. In attempting to make an assessment of agricultural efficiency we should require as a minimum basis a body of statistical information on the following points: first, the numbers of persons engaged; second, average yields per acre of certain crops for comparison with average yields in other producing countries; and third, statistics of output measured in man-hours according to recognized methods of determining the productivity of labour. The type of dficulty mentioned here is not confined to research in ancient agriculture; lack of records, and paucity of precise information, make investigation difficult in almost every department of ancient economic history. But lack of precise information has not deterred historians from making rough analyses and generalizations. The evidence on wheat-yields showed, inter alia, that it is not legitimate to use Columella’s general average return on Italian wheat of four-fold as evidence of a generally low standard of productivity in cereals (De Re Rust., III, iii, 4). So far as crop-yields are concerned, the common postulate of a low level of agricultural technique cannot be upheld.

It will be useful first of all to recall some dates: 1848—the Communist Manifesto; 1859—Contribution to a Criticism of Political Economy, in the introduction to which Marx made his clearest definition of the materialist conception of history. It was also the year of Origin of Species and the authentication of Boucher de Perthes’ handaxes. ‘Relics of bygone instruments of labour possess the same importance for the investigation of extinct economical forms of society as do fossil bones for the determination of extinct species’ . This quotation is from the first volume of Capital published in 1867, which Marx had wished to dedicate to Darwin; Darwin declined the honour. We know from the chapter ‘The Part Played by Labour in the Transition from Ape to Man’ in Engels's Dialectics of Nature, written in the 1870s but published posthumously 40 years later, that Engels had been thinking about prehistoric man, although he evidently had not got very far beyond Marx's description of labour in Capital.

There are several kinds of fossil sea-urchin that are the subject of folklore, the commonest in the south of England being casts in flint, derived from the Chalk, of the heart-urchin Micraster, and of the helmet-urchin Echinocorys. Both of these, but more commonly the latter, are known to the country people as shepherd's crowns or fairy loaves (PL. xxib). Formerly at least, the Essex labourer believed that so long as one of these fossil sea-urchins was kept in the house, his family would never go short of bread (Johnson 1908, 149). At a number of localities in southern England fossil echinoids are traditionally placed on dairy shelves to keep milk from going sour. This practice is clearly linked with the ancient idea that these fossils are thunderstones.

The earliest known case of fossil echinoids being used in a ceremonial burial is in the Early Bronze Age tumulus on the Dunstable Downs, where nearly IOO shepherd’s crowns, mainly Micraster, had been arranged to encircle the bodies of a woman and child (Worthington Smith 1894, frontispiece, 337-8). H. S. Toms collected evidence that up to the middle of the last century fossil sea-urchins were called thunderstones throughout Sussex, whereas they are now simply regarded as ‘lucky’ (PL. XXIIb), and if seen in the soil and not brought home, at least one should spit on the shepherd’s crown and throw it over the left shoulder. Even the idea of luck being attached to sea-urchins found on the fields has disappeared latterly from many villages. As there were still scattered traces of the thunderstone belief in Sussex in 1930, it is probable that more than a century ago the thunderstone aspect was dominant there. This idea survived longer in West Sussex than in East Sussex, and oral tradition can be traced back to 1860.

The chambered long barrow known as Wayland's Smithy lies a little south of the crest of the Berkshire Downs, about a mile west of the Uffington White Horse, within an oval plantation of beech trees. The excavation here described was carried out during II weeks in 1962 and 1963 under the direction of Professor Stuart Piggott and the writer. The barrow has now been restored to its appearance in antiquity, so far as the surviving features allow.

Before excavation, the site appeared as a long low mound, much flattened by cultivation and erosion, with a length of about 200ft. and a maximum height of about 4ft. above the surrounding surface. At the south end were the ruined remains of a cruciform burial-chamber constructed of large sarsen slabs, in front of which was a line of four large fallen stones, evidently parts of a massive fayade similar to that of the West Kennet long barrow. To the east, a row of four smaller sarsens, still upright, marked the line of the kerb of slabs which had once delimited the mound. A sketch made by John Aubrey in the mid-17th century shows that apart from the presence then of additional visible kerb-stones the appearance of the site has altered little in the last 300 years.