Glossary
Gondwanaland: The large southern supercontinent formed almost 200
million years ago by the breakup of Pangaea; included South America,
Antarctica, Australia, Africa, and India; see also Laurasia.grand narrative: Term used in post-modern theory to describe overarching
accounts of reality (such as Marxism, or big history); points to the danger
that such accounts can mislead or be put to self-interested uses.grand uni¿ ed theory: The idea of a single, uni¿ ed scienti¿ c account of all
aspects of physical reality; the holy grail of modern physics since the 1960s;
remains elusive because of the failure to merge relativity and quantum
physics or to explain the nature of dark matter/dark energy.hafted tools: Tools attached to handles.half-life: The period during which half of the mass of a given radioactive
material decays; the precision with which half-lives can be calculated
for different radioactive materials is the basis for most forms of
radiometric dating.helium: The second-simplest atomic element, with two protons and two
electrons, produced, like hydrogen, soon after the big bang; helium made up
about 24% of the matter in the early Universe but now makes up about 28%
as fusion reactions have converted hydrogen atoms into helium.hominids/hominines: Bipedal apes, ancestors of modern humans; ¿ rst
appeared 6–7 million years ago.Hominoids/Hominoidea: The superfamily of apes (includes humans).Homo erectus/ergaster: Hominine species that appeared in Africa almost 2
million years ago; almost as tall as modern humans, their brains were larger
than those of Homo habilis; some erectus migrated into Eurasia, reaching as
far as China.Homo habilis: Hominine species that appeared in Africa between 2 and
3 million years ago; classi¿ ed by their discoverer, Louis Leakey, within