Glossary
kin-ordered societies: A term used by Eric Wolf to describe all human
societies in which kinship systems are the most important basis for social
organization; all societies before the appearance of the ¿ rst tribute-taking
states can be regarded as kin-ordered.later Agrarian era: From c. 3000 B.C.E. to a few centuries ago; the second
part of the Agrarian era, in which there existed Agrarian civilizations;
synonym for “era of Agrarian civilizations.”Laurasia: The large northern supercontinent formed almost 200 million
years ago by the breakup of Pangaea; included Eurasia and North America;
see also Gondwanaland.macrohistory: Study of the past on large scales.Malthusian cycles: Long cycles of economic, demographic, cultural, and
even political expansion, generally followed by periods of crisis; warfare;
and demographic, cultural, and political decline. These cycles, generally
lasting several centuries, are apparent throughout the Agrarian era and were
probably generated by the fact that, though there was innovation (which
generated the upward swings), rates of innovation could not keep pace with
rates of growth (which explains the eventual crashes).mantle: Layer of the Earth between the core and the crust; the mantle is
semimolten, and convection currents within it drive plate tectonics.margins, tectonic: Regions where tectonic plates meet; this is where
most interesting geological events occur, including mountain building,
earthquakes, and volcanic activity.matter: As Einstein showed, matter and energy are interchangeable
(according to the famous formula, e [energy] = m [mass] × c [the speed
of light]^2 ); matter can, therefore be regarded as a form of congealed
energy; for much of the ¿ rst second of the big bang, matter and energy
were still interchangeable.