conceptual leakage
nThis can
be illustrated with a concept from linguistics
nLanguage phyla or subgroups are presently defined by the
languages that are either synchronically spoken or are
attested from epigraphy or historical sources.
nThe Nilo-Saharan languages are one of the oldest language
phyla of Africa and so are in retreat or encapsulated
in many areas
nThere are no epigraphic sources for the wider extension of the
phylum
nNonetheless, a ‘bundle’ of diverse evidence,
from archaeology to iconography to contemporary material culture
makes it highly likely that Nilo-Saharan once spread
over a much greater geographical area
nIf we therefore identify non-linguistic
‘bundles’ with language phyla expansions we can then
borrow such interpretations to explain new
archaeological data