Across Atlantic Ice

by Dennis J. Stanford

  Developing accurate long-range shooting equipment for hunting in an open steppe environment would have been necessary, in addition to learning completely new sets of hunting skills. The formation of large, organized groups of hunters for animal trapping and manipulation would have provided an advantageous edge for survival during these times. All of these innovations, necessary to efficiently exploit the newly emerging open steppe, would have been equally adaptable to hunting ice edge environments.

  The simple sharp-pointed thrusting spears used by humans throughout the majority of our time on earth were improved. New weapons had multiple parts, including fore-shafts, with socketed projectiles to which end or side blades were attached. The least complicated of these innovations were thrusting spears with a projectile point made of flaked stone, bone, antler, or ivory.

  More complex systems were developed with shaft modifications that accommodated new propulsion methods suited to the new hunting situations. These included darts cast with throwing boards and arrows shot by bows. The latter are conjectured based on the size of single-shouldered points and on small-stemmed projectile points found primarily in southern Spain and Portugal. The simple thrusting spear was further improved by the attachment of a self-barbed spear point (see figure 5.4a).

  All of these systems have different and multiple hafting arrangements, including rigidly mounted points and detachable, interchangeable, and replaceable parts (figure 7.5). Multiple components can include a blade set into a harpoon-like socket, the latter either firmly fixed to the foreshaft or designed to break apart from it on impact. Likewise foreshafts and shafts could be firmly fixed together or designed to break apart on impact. All of these systems might or might not have had cords or lines attached to either the blade socket or the foreshaft. The advantage of the line is that it allows the hunter to hold onto the shaft or attach the weapon tip to a weight or float. When an unfortunate beast reaches the end of the cord, either it is held fast or the weapon tip is torn from its body, causing an ugly, lethal wound. Attachment accommodations are most important for aquatic hunting, since they provide for the retrieval of dead or wounded animals before they sink beneath the water. It is thought that line holes drilled through Magdalenian harpoon heads represent the beginning of aquatic harpoon technology.16 However, lines were not that necessary during the LGM, since the elevated salt content of the seawater kept mortally wounded animals from sinking rapidly. Retrieval could have been accomplished in many ways, including boating out, casting a grappling hook and line, or simply waiting for the animal to drift ashore.

  Perhaps as important to Solutrean hunters as the efficiency of the new weapons was the fact that these break-apart systems allowed for the retrieval and long-term survivability of spear shafts. Because of the deforestation of the Spanish countryside during the LGM, long pieces of wood suitable for spear shafts were likely rare. Even before then, from searching for suitable pieces of wood to shaping and straightening, shaft construction was a major time-consuming process. The development of detachable foreshafts likely saved many a spear shaft from ruin and allowed the hunter to retrieve the shaft. This was a particular novelty in aquatic environments. Such systems also allowed hunters to re-arm with a new weapon tip and take additional shots at other targets. Consequently, we agree with Straus that Solutrean hunters used foreshafts, and we propose that some of the bone and antler rods with blunted or rounded distal ends were probably used as foreshafts rather than projectile points.17

  A relatively wide variety of stone and bone artifacts found in Solutrean sites have been identified as projectile points. These include unifacial and bifacially flaked stone points of various shapes, such as laurel leaf, willow leaf, shouldered, concave base, and tanged, as well as several kinds of bone and antler points with hafting arrangements and modifications for the insertion of stone side blades. Some of these point types may be associated in the same occupation levels in various sites, but the variety of point types and number of forms vary in different areas and throughout time. Thus, Solutrean occupations can be distinguished by having some point types and not others. Part of this variation is probably temporal, but some of it may be ethnic, with overlap resulting from contact between regional bands or from population movements. It is also possible that different point types correspond to weapons used for hunting specific types of game.18

  The self-barbed spear point and the indented base point first appear at La Riera in level 4, the beginning of the second phase of the Solutrean occupations. Self-barbed spear points are slightly curved bipointed bone or antler rods that are flattened and scored on the curve’s outside surface so they can be hafted to a spear shaft with both ends of the point exposed (figure 5.4a). The leading point is for penetration, and the trailing point acts as a barb to attach the weapon securely to the prey so it can’t drift away or sink. The presence of self-barbed points and fish remains in Solutrean levels, combined with the fact that similar weapons are still used by various groups for fish spearing, makes an excellent case for Solutrean people’s using these artifacts in the same activities. This type of spear would have been equally effective for hunting seals at breathing holes and serves the same function as a metal sealing pike.

  Straus has suggested that indented base projectile points (figure 5.10) and end blades were used on regular thrusting spears, while small single-shouldered points were used on the slender shafts of darts cast by spear throwers or on arrows (figure 5.6c).19 In a sample of 100 shoulder points, he found an average maximum width of 1.37 centimeters with a standard deviation of 0.30 centimeters, while 45 concave base points had an average width of 2.29 centimeters and a standard deviation of 0.42 centimeters. These differences in width support the notion that the two types of points were indeed hafted differently.

  To examine this idea, we compared Straus’s measurements to those calculated for triangular stone points from Late Prehistoric sites along the California and Oregon coasts. At these North American sites, arrows and harpoons were used to hunt terrestrial and aquatic mammals, respectively. In a study of West Coast projectile points, Lee Lyman, Linda Clark, and Richard Ross found that arrow points with small concave bases have an average width of 1.42 centimeters with a standard deviation of 0.22 centimeters.20 Larger concave to straight base points—which were used as tips for bone or antler harpoons when hunting sea mammals, according to native informants—averaged 2.95 centimeters with a standard deviation of 0.33 centimeters. These figures compare favorably to both Solutrean point styles in Straus’s theory, supporting his idea that the narrow-shouldered points were used on arrows or narrow dart shafts and the broader concave base points on heavier spears. (Such heavier spears may well have been tipped with harpoon-like sockets armed with end blades.) The theory is further supported by the coastal distribution of Solutrean concave base points (figure 8.1).

  In summary, it appears that most of the new weapon systems developed during Solutrean times were ideally suited for open steppe and aquatic hunting. Among the innovations for which there is tangible evidence are spear foreshafts and harpoon-like end blades; both strongly imply that Solutrean hunters used detachable end blade sockets, which are found in most if not all primitive marine mammal hunting tool kits. Further, the self-barbed spear is an unquestionably aquatic hunting adaptation that historic northern Europeans used for hunting seals at breathing holes. Although the presence of these weapons does not prove that Solutrean peoples hunted marine mammals, it does mean that they had developed the equipment to do so, and there is no reason to suspect that they would not have thought it a good idea—especially while visiting the coast during the prime seal-hunting months.

  Inasmuch as the evidence suggests that Solutrean culture existed for some 3,500 or more years and that during most if not all of this time a major part of their settlement system was directly adjacent to or at least in view of the ice age sea, we consider it entirely unlikely that these acknowledged great innovators would not have learned to understand and exploit this environment. In
fact, it is possible that many of the innovations with which they are credited were the direct result of a maritime adaptation.

  9

  THE LAST GLACIAL MAXIMUM

  How Bad Was the Weather?

  The ice age world in which the Solutrean people lived had climatic conditions so different from ours that they are difficult to imagine. Our modern circumpolar regions might serve as analogues to provide us hints about surviving in such conditions, but we must be aware of the major differences from even these Arctic backdrops. For instance, a whole host of now-extinct animals, such as mammoths, mastodons and saber-toothed lions, lived side by side with early humans. The LGM climate caused the formation of huge ice caps that covered more than half of the Northern Hemisphere and were several miles thick in some places. This accumulation of ice reduced ancient sea levels by hundreds of feet, expanding continents and exposing new lands for plants, animals, and people to colonize.

  These events produced an environment that although not idyllic was understood and exploited by those peoples who lived during the LGM. It is under these radically different conditions that we hypothesize Solutrean people adopted a maritime economy and, while exploiting marine resources, crossed the Atlantic.

  PALEOCLIMATOLOGICAL MAPPING

  To understand the Paleolithic world, scientists have reconstructed past environments on the basis of fossil plant parts and pollen found in archaeological sediments and extracted from cores of dated sediments taken from lakes and bogs. Modern plant and animal communities can provide analogues for the extinct Pleistocene species found in Paleolithic sites, and their environmental requirements can be used as proxy indicators of past environments. After many years of research aimed at deciphering past environments, we are only now beginning to understand how complex and interconnected the web of natural phenomena was that shaped the ice age world.

  During the 1970s a large-scale program known as CLIMAP (Climate: Mapping, Analysis, and Prediction) was established to synthesize oceanographic paleoecological data and produce models of past climates that would explain why climates change and thus help us to understand our present climate better, as well as predict the climatic events of the future . . . such as global warming.1 The CLIMAP project was so successful that it stimulated another project, COHMAP (Climates of the Holocene—Mapping Based on Pollen Data), which had the same objectives but concentrated on terrestrial paleoclimatic data.2 Another project, known as EPILOG (Environmental Processes of the Ice Age: Land, Oceans, Glaciers), was established in 1998 to assess the advances made during the preceding twenty years of paleoclimatic research.3 The goals of this project are to find points of consensus, resolve conflicts in data, set standards, and outline a plan for a new synthesis of evidence about the LGM.

  Because of these and related projects, our ability to refine our interpretations of these early environments has improved dramatically, and we are able to draw an increasingly accurate picture of past climates.4 The important sources for climatic data come from studies of ice cores pulled from the Greenland and Antarctic ice caps and deep-sea cores taken from sediments deposited on the ocean floors. Refined techniques for analyzing pollen from lake, pond, and marsh sediments also sharpen our interpretive abilities. The principles underlying these methods are similar to those applied to lake varves, the layering of successive soils from storms deposited in the bottom of a lake that reveals climatic events that occurred in that local area. Ice cores are the best source of data for the climatic history of the Northern Hemisphere, for they provide a continuous record of annual and seasonal ice deposition. Each layer is like an entry in a diary, documenting worldwide events ranging from rainfall to volcanic eruptions.

  Sediment cores taken by drilling ocean floors are being correlated with the Greenland and Antarctic ice cores to provide an even more refined record of past climatic events and a wide variety of other phenomena that aid in the interpretation of global climatic history. For instance, mapping the presence of specific rocks and debris released by melting icebergs and preserved in deep-sea cores across the ocean floor can identify the location and direction of flow of ice age ocean currents. Dust and rocks were incorporated into the ice as glaciers cut through the continental landforms. When the glaciers eventually reached the sea, large chunks of ice broke away, forming icebergs. As these floated along on ocean currents, they melted, leaving a trail across the ocean floor of fine dust particles, rocks, and debris, along with their trace element signatures. Scientists refer to this material as ice-rafted debris, or IRD. Melting icebergs from northeastern Canada carried debris consisting of limestone from that area, bergs from Iceland contained basaltic glass, the IRD from the British Isles was composed of chalk, and so on. When IRD is correlated between cores, it identifies the routes the icebergs followed and provides maps of the courses of the ancient ocean currents (figure 9.1).5

  FIGURE 9.1.

  Reconstruction of primary ocean currents and the North Atlantic sea ice cover during the Last Glacial Maximum. (Based on de Vernal and Hillaire-Marcel 2000; Dyke and Prest 1987; Lambeck 1995; Pflaumann et al. 2003; Preece 1995; Rida and de Vernal 2008.)

  Calcareous oozes on the ocean floors contain the remains of tiny marine organisms such as coccolithophorids, diatoms, dinoflagellates, foraminifers, and ostrocods, among others that once lived in the waters above. After dying they sank to the bottom of the ocean and were buried in the ever-growing ooze deposit. When extracted in a deep-sea core, their fossil remains enable scientists to estimate past sea surface temperatures, sea level changes, and volumes of land ice, among other phenomena.

  We know the environmental tolerances that control where these organisms live today, and the ratio of oxygen isotopes in their skeletons correlates with seawater temperature changes.6 Isotopic analyses of each foraminifer species in a deep-sea core are plotted against their depth in the core to provide a record of changes in water temperature. Neogloboquadrina pachyderma signals the coldest water; hence when it is highly abundant in a core it is thought that the sea surface temperature above was cold (figure 9.2). The time-transgressive isotope curve can also be used as a proxy index of global sea levels, with maximum peaks representing warming periods and minimum peaks representing cooling episodes, during which ice sheets grew and global sea levels fell. The warm stages have been given odd numbers and the cold periods even numbers. The information so acquired makes it possible to reconstruct past ocean environments and their productivity, which in turn tells us what sea organisms could have survived in these polar and subpolar marine environments.

  FIGURE 9.2.

  LGM cooling and warming trends as reflected in the Greenland ice cores. Temperatures changed relatively often and the LGM Ice Age was not a event, but a complicated process during which the Polar Front moved southward during colder periods and northward during warmer periods.

  Paleoclimatological mapping has produced some surprising results. We have long talked about four ice ages.7 It is now apparent that multiple events during the Pleistocene represented long-term cooling trends, known as Bond cycles, and incorporated many shorter ice advances that alternated with periods of warming.8 Heinrich events, named for Hart-mut Heinrich, were periods when massive amounts of ice calved off glaciers and formed huge packs of icebergs.9 Although we once thought that creating an ice age took millennia, we now realize that drastic climatic change can happen extremely rapidly, perhaps even within a few decades.10 Climate change is a highly complex phenomenon that is affected by a vast network of processes, events, and relationships as yet incompletely understood. Science has made great strides in the past few years in determining the nature of our planet’s past climates, and future research promises to refine these interpretations.

  The following discussion represents our synthesis of the climates and environmental changes during the LGM. We are primarily interested in the data from the interval encompassed by Heinrich events H1 and H2 (16,000–24,000 years before the present). Within these stages, cycles, and events there were many
rapid and longer-term fluctuations in the climatic parameters, which required our Paleolithic ancestors to develop a broad range of survival skills. Some climatic episodes would have been more hospitable to land and maritime resource exploitation, others less so.

  LGM OVERVIEW

  During the LGM temperatures in the high-latitude Northern Hemisphere dropped to an unprecedented low. Snow and ice accumulated until they formed massive glaciers in the high elevations and latitudes around the world. Two major glaciers developed in North America: the Laurentide centered on Hudson Bay, and the Cordilleran formed in the Cascade Mountain Range of British Columbia.11 These glaciers began to develop more than 24,000 years ago and expanded outward from their centers. Their margins eventually collided along a roughly north-south axis from the Yukon to southwestern Alberta, forming one solid ice cap over the top of the Americas that lasted nearly 8,000 years. These glaciers began to recede after the LGM, opening an ice-free corridor. Eventually their remnants existed only in higher mountain valleys and other minor locations in Canada and Alaska. Glacier National Park contains some of the last southern traces of the LGM ice fields and serves as a reminder that these climatic episodes are not static events but ongoing processes.

  The Fennoscandian Glacial System developed in northern Europe, spread westward to the North Sea, and pushed southwest toward the Saône River in France (figure 9.1). It also grew east- and southward, combining with smaller local glaciers to cover the top of the continent and uniting much of Europe and Asia under a single massive ice cap. A smaller glacial system, the British and Irish Ice Sheet blanketed the British Isles except extreme southwest Ireland and parts of southern England.12 Many smaller glaciers also developed in the Alps, the Pyrenees, the Picos de Europa, the Brooks Range in North America, and elsewhere. But they played their part: although the Greenland Ice Sheet was relatively small in extent, it was more than 3,000 meters thick.