Glossary
Pangaea: The vast supercontinent formed more than 200 million years ago
as plate tectonics joined most of the major continental plates together; it is
probable that such supercontinents have formed periodically throughout the
Earth’s history; the existence of a single huge landmass probably reduced
biodiversity.paradigm: The central organizing idea of a scienti¿ c discipline, such as
natural selection (in biology), big bang cosmology (in cosmology), or plate
tectonics (in geology); as yet, history lacks a paradigmatic idea; the term is
associated with the work of philosopher of science T. S. Kuhn.parallax: The change in the apparent relationship between two ¿ xed
objects caused by the movement of the observer; if you hold your ¿ nger
up and move your head, your ¿ nger will appear to move against the
background; parallax measurements can be used to measure the distance to
the nearest stars.pastoralism: A life similar to agriculture but based primarily on the
exploitation of domesticated animals rather than plants; in order to allow
animals to graze over large areas, pastoralists are generally nomadic;
pastoralism was made possible as a result of the innovations of the secondary
products revolution and spread widely in the steppelands of both Eurasia
and Africa.patriarchy: Ideologies and social structures that assume the superiority of
males over females.peasants: Small holding farmers, who generally pay taxes to overlords; the
most numerous class in all Agrarian societies.periodic table: A way of listing chemical elements in groups with common
features; ¿ rst constructed by the great Russian chemist Dmitrii Mendeleev
in 1869.photosynthesis: The use of sunlight by plants or plant-like organisms to
store energy; ¿ rst evidence from c. 3.5 billion years ago; the source of most
of the energy that drives life within the biosphere.