Series in Ancient Technologies
Ancient Iowans used many kinds of animal bones as raw material for tools. Along with artifacts of stone, shell, and wood, bone implements were an important part of many tool kits. As a raw material, bone is tough and slightly brittle. With only slight modifications, the scapulae (shoulder blades) of bison and elk could be made into hoes, and the ulnae (foreleg bones) of deer could be worked into awls. Other types of tools such as fishhooks required considerable labor to reach their desired form.
Modified bison scapula
Softer than most stone and harder than wood, the hardness and resilience of bone made it particularly useful. Fresh bone can be split, broken, and splintered. Relatively fresh bone can be modified in various ways, depending on the form and size of the bone and the type of tool desired.
The simplest means of modifying bone is by breaking the bone on an anvil with a large hammerstone. This technique was commonly employed to extract nutritious marrow from the bone cavity. Long bones of large.animals can be cracked and broken into sharp splinters suitable for immediate use as picks or scrapers or for further modification into awls and other tools. This technique of breaking bones is relatively haphazard, but when coupled with other methods such as grooving or sawing, it can be used to shape more sophisticated tools.
Breaking bone using the anvil method
Grooving and Splitting
For some delicate bone tools, it is first necessary to score the parent bone. Grooves outlining the intended tool's form are cut through the hard outer bone to the spongy cancellous tissue using stone tools such as sharp pointed gravers and chisel-ended burins. The piece can then be broken free with relative ease and made into an awl or needle. Grooving bone with a modified flake tool can be slow. Soaking the bone in water for a few days can speed up the process by temporarily softening the bone, making cutting and scraping easier. Once the bone is dry, it will return to its hard, resilient state.
Using a graver to groove bone
Sawing, Drilling, and Grinding
Bone can be sawed into sections with a serrated bifacial stone knife or flake tool. After the saw cuts have been made to a sufficient depth, the bone can easily be broken by hand. Stone drills, either hand held or attached to shafts, may be used to bore holes through bone for making such tools as arrow-shaft wrenches. The small eyes of sewing and matting needles can be made by a sawing or twisting motion with a graver tip.
Polishing, final shaping, and sharpening were done with a sandstone abrader. Some tools were made almost totally by grinding.
Bone Tool Types
Since bone is not a universally well preserved material, we know little about the bone tool technologies of the cultures prior to the Late Prehistoric period. One of the earliest musical instruments, however, a bone flute, was recovered from an Early Archaic site in western Iowa.
After AD 1000, bone tools are well known. The Mill Creek culture of northwest Iowa (ca. AD 1000_1250) exhibits a particularly rich assemblage of bone artifacts. Bone tools are often categorized according to their supposed functions.
Late Prehistoric agricultural groups of the Midwest and Plains commonly made hoe blades from the scapulae of bison and elk. The long spine that runs the length of the bone may be easily broken off after a few deep saw cuts have been made. Portions of the bone may be broken away to give the blade a more symmetrical appearance. After the edge has been beveled and ground sharp, the hoe blade is ready for mounting in a split and notched wooden handle.
So-called squash knives also were made from the scapulae of large mammals. These tools were made by selecting a portion of the broken shoulder blade and grinding the thin interior bone edge sharp. Such tools would have served well in slicing soft plant materials.
Bone squash knife
Scoops were made from the bison horn core and accompanying portion of the frontal bone. These tools were probably made by breaking off the desired piece of the skull and grinding the exposed edge sharp. Horn scoops were probably used as hand-held digging tools.
Horn core scoop
Saw-tooth-edged tools were commonly made from the long bones of large animals, particularly the metatarsals (long foot bones) of bison and elk. By breaking the distal end off at an angle and then sharpening and serrating the exposed edge, the tool could be used to strip the fatty tissues from the inner surfaces of fresh hides.
Tools for scraping and smoothing the inner surfaces of hides were made by breaking off the heads of a leg bone of a bison or other large mammal, exposing rough cancellous interior bone.
Deer jaws were used in an unmodified state for threshing grasses. The front portion was frequently worked away and polished smooth.
Deer mandible sickle
The ribs of bison and elk as well as the long bones of deer were sometimes drilled with holes for use in straightening arrow shafts. When arrow shafts were heated, these wrenches helped remove warps or irregularities.
Arrow shaft wrench
Fishhooks were made by two methods depending on the bone used. Toe bones of deer were cut and split lengthwise. The exterior surface of the bone was then removed by grinding, leaving only the hook-shaped ridge of bone inside. Larger fishhooks were made by grooving and grinding oval-shaped pieces of a split rib.
Fishhooks are believed to have been manufactured from bone "blanks."
Awls, used as leather punches in sewing hides, were made from a variety of bones. The ulnae of deer could be cut, and then ground and polished to form a sharp tip. Splinters of rib and long bone were also ground into awls. Hollow bird bones also were sometimes broken and split to form awls.
Awl made from an ulna
So-called quill flatteners are flat-ended tools made from long splinters of mammal bone. The rounded and flattened ends of these tools are thought to have been used in flattening porcupine quills for use as decoration. They may also have been used as pressure flakers in flintknapping or for smoothing in pottery making.
Like bone, antler is tough and resilient. Unlike bone, however, antler is relatively solid and varies greatly in form among individual deer. Antlers are grown by male deer and are shed each winter. Antlers were perhaps most important to prehistoric groups for use as flintknapping tools. Soft hammer batons for controlled percussion flaking were made from the basal portions of antlers by cutting them to length and grinding off the rough burr at the base. Antler tips, cut to lengths of 3 to 10 inches, were used as pressure flakers. Antler tips were sometimes cut and drilled to make conical arrow points.
Base of antler used as soft hammer baton
Antler tine used as pressure flaker
Adapted from a manual prepared by Toby Morrow.