Historical Linguistics and Language Families 4, Exercise 3: starred forms and homelands

*ph₂tḗr   father
*wódr̥     water
*gʷṓus    cow

Why the asterisk: these words were never recorded; they are reconstructed
from the descendant languages, and the asterisk marks them as hypotheses.

Homeland views (Wikipedia, Proto-Indo-European language):
  Kurgan hypothesis: the Yamnaya culture on the Pontic steppe, around 3400 BCE
                     (first proposed by Marija Gimbutas, 1956).
  Anatolian hypothesis: spread from Anatolia with agriculture, beginning
                     around 7500-6000 BCE.

The page presents these as the two most widely accepted and most debated.