However systematically archaeological digs are conducted, many of the prehistorians' discoveries have been made by chance. Since it is not possible to ransack the face of the whole world to find stone implements, burial places or other relics, it is to be hoped that when someone turns up something unusual he will be intelligent enough to inform the specialists.

Such a man was one Olsen, owner of Meilgaard Farm in northeast Jutland. In 1849, having decided to cut a road through his property, he told the workmen to dig into a mound near the seashore, covered with trees and brushwood. He believed it to contain gravel, but instead of gravel the labourers found beneath the top-soil a bed of shells over seven feet thick. Olsen was not disheartened; suitably pounded and crushed the shells would help to form a solid roadway. The fact of their being heaped was in no way surprising: piles of empty shells lay scattered all along the northern coasts of Denmark. But Olsen rubbed his eyes when the workmen brought out of this layer of shells flint implements, animals' bones and a four-toothed comb of bone, finely worked and pierced. Olsen sent the comb to the National Museum in Copenhagen.

It was a fortunate decision, for the packet was opened by Jens Jacob Asmussen Worsaae, a pioneer of prehistoric research. His interest roused, he began to wonder whether the sporadic heaps of shells along the Danish coasts might not be the work of primitive man. He immediately sent out a working party with instructions to make an inventory of the contents of several well known shell mounds. He himself went to Meilgaard Farm, to talk to Olsen, and had the good luck to discover in the mound several finds of the greatest interest.

He found that the oyster and mussel shells had been deliberately opened by people intending to eat the contents. Flint tools, polished and pointed antlers, bones from which the marrow had been scraped out, potsherds and cinders were brought out one after the other. All the evidence tallied: the piles of shells were the remains of meals left in heaps by men who fed upon molluscs collected at low tide. To what period should they be assigned? In his report Worsaae wrote cautiously: 'It seems permissible to suppose that this spot was one at which the local inhabitants of a very early period were wont to meet and have their meals.'

He was to be proved right. In the course of the next few years, especially in the 1890s, Danish prehistorians studied the problem of the shell mounds and concluded that they dated beyond all doubt from the Middle Stone Age. In addition to the shells of oysters, mussels and cockles the mounds included those of crustaceans and snails, the bones offish, ducks and other birds, particularly sea birds, and those of seals, dolphins, deer, wild pig, lynxes, wolves and smaller mammals. Some had apparently been gnawed by dogs, from which Johannes Steenstrup deduced that the inhabitants of the period had owned domesticated canines. The implements were of stone, horn or antler; none of the sites contained either metal objects or any indication of the contemporary existence of agriculture or pastoral life.

The Danish kjokkenmoddingen (' kitchen middens') have an antiquity of seven thousand years, a period when the North Sea was encroaching on the land and Denmark was finally separated from Sweden. Nor are those piles unique; the concheros of Spain and Portugal, the sambaquis of Brazil, the monticules along the coasts of South Africa, Australia and Japan all show that the inhabitants of the land masses settled everywhere by the sea and fed upon the creatures of the beaches. It is clear that the people of the shell mounds did not live entirely upon molluscs; they fished, gathered fruit and berries too, and, like their forbears, hunted in the coastal forests. The new fact is that they scarcely left the littoral; squatting there they built shelters and huts, and thus from generation to generation refuse—shells, bones—piled up close by the settlements. Some of the mounds were raised over a period of a thousand years.

Archaeology has revealed also that men who fished and hunted reached the coast of northern Scandinavia and settled along the shoreline when the sea level was several hundred feet above its present level—perhaps as early as 7000 b.c. The remains of this Komsa culture (which lasted several thousand years) so far discovered are confined to stone tools and implements, but these include arrowheads and axes. Where did these people come from?

Many theories have been put forward, assigning them origins in central Russia, Siberia or the north European plain, and postulating a variety of routes by which tribes trekked through forests or down rivers to reach the Arctic coast. Professor Anders Hagen,* however, summarizing the evidence with proper caution, infers that 'these tribes of Finnmark were the most northerly of all the known groups of the Early Stone Age', and that they may more plausibly be associated with the contemporary or earlier coastal settlements of the hunting-fishing Fosna culture numerous around the fjords north and south of Trondheim. Hence, a coastwise route up the length of Norway to the Arctic seems the most probable.

It is reasonable to conclude that, as the ice withdrew, men of the post-glacial period followed the herds of wild animals as these slowly moved north with the shifting belts of vegetation. People who had lived by hunting the creatures of the tundra, such as reindeer, would not readily adapt to forest living, and in any case there was no sudden change in conditions. Did these Old Stone Age people already have boats? It is tempting to think so. Among the rock carvings of Scandinavia, generally ascribed to an unspecified period in the Stone Age, is a group at Tysfjord, south of Narvik, showing reindeer and other animals and the unmistakable outline of a whale, about twenty-five feet long. The question arises: was man capable of hunting the whale in the Early Stone Age?

Such hunting cannot, of course, be thought of apart from boats. Rock engravings have been found in which figure small primitive craft, whales, dolphins and seals. In shape these boats are suggestive of the umiaks, or skin boats, manned by Eskimo women. The first, or at least early, colonists of the Norwegian and Arctic coasts could have made them from reindeer skins stretched over a framework of wood. If, in such fragile boats, they ventured into the ocean and harpooned the mammals of the sea, the first stage of the conquest by man of the ocean, so fraught with consequences, may date back beyond the Mesolithic shell-mound period.