Glossary
prokaryotes: Simple, single-celled organisms in which the genetic material
is not bound within a nucleus.
proletarians: The term used within Marxist theory to refer to wage earners,
those groups who could bring to markets nothing but their own labor power.
proton: Positively charged subatomic particle present in the nuclei
of all atoms.
punctuated evolution: The idea ¿ rst proposed by Stephen Jay Gould
and Niles Eldredge in 1972 that the pace of biological evolution can vary
signi¿ cantly, so that the history of biological species consists of long periods
of relative stasis “punctuated” by periods of abrupt change.
quarks: The fundamental constituents of neutrons and protons.
quipu: Knotted strings used by the Inka for accounting and as an embryonic
form of writing.
radiometric dating techniques: Techniques for determining the dates
of origin of materials by measuring the extent of the breakdown of
radioactive materials.
Rapa Nui: A Paci¿ c island (also known as Easter Island) owned by Chile,
¿ rst settled by Polynesian navigators approximately 1,000 years ago and
remarkable for the presence of many large stone ¿ gures.
rebus principle: A critical stage in the evolution of writing; if an object that
could be easily depicted (say an arrow) sounded similar to a more abstract
concept (such as soul), the symbol for the ¿ rst could be used to refer to the
second; this device greatly expanded the ability of written language to mimic
spoken language.
reciprocity: Mutual exchanges of gifts; in kinship societies, one of the most
powerful ways of holding communities together through the creation of
mutual obligations.