Chemistry Reference
In-Depth Information
molecules comprising many thousands of atoms. Such molecules, which are
usually referred to as
macromolecules
or
biopolymers
, are produced by the
living organisms from relatively small molecules, known as
monomers
, joined
together in a repeating fashion. Well-known examples of natural biopoly-
mers are the
carbohydrates cellulose
, the most abundant substance in the bio-
sphere and
starch
; also most of the
proteins
and
nucleic acids
, all of which are
an integral part of, and fulfill specific functions in all living organisms.
Since time immemorial, humans learned to utilize organic sub-
stances and materials consisting of mixtures of organic substances derived
from plants or animals for particular tasks: mostly for food, but also
for making body coverage and adornment, building dwellings, making
tools and weapons, and countless others functions. The materials listed
below, all organic materials, are examples often found in archaeological
excavations:
Amber
Fat
Horn
Paper
Skin
Antler
Flax
Incense
Papyrus
Sugar
Charcoal
Food
Ivory
Parchment
Vellum
Cork
Glue
Lacquer
Perfume
Wood
Cotton
Gum
Linen
Resin
Wool
Dyes
Hair
Oil
Silk
Wax
The nature and properties of the organic substances, the ways in which
humans have used them, and the information that may be derived from the
study of their composition and characteristics in archaeological contexts are
discussed in the chapters that follow.
Bioinorganic Substances
Organic substances are not, however, the only substances created by living
processes. Some biological processes, quite widespread in nature, result in
the formation of inorganic substances that are thus known as
bioinorganic
substances
or
biominerals
. Biominerals of archaeological interest are listed in
Table 64 (see also Chapter 15). Some bioinorganic processes proceed in ways
that may be of use for solving archaeological problems. The exoskeletons
(shells) of some invertebrate animals, such as snails, for example, increase
in size during the growth process by accretion, that is, by the addition of
new material at the edge of earlier formed skeletal structures. The rate
of growth of the accreting material is affected by variations in environmen-
tal conditions, such as temperature and rainfall; this gives rise to the
