Almost all of Europe was possibly settled before or during the last
ice age ca. 10,000 years ago.
and modern man
coexisted during at least some of this time. Roman road building helped with the
of the native Europeans' genetics.
In contemporary times Europe has one of the lowest inbreeding rates in the world because of an
extensive transport network paired with open borders.
Europe passed well over 600 million people before the turn of the 20th century, but now is entering a period of population decline,
for a variety of social factors.
Sources: University World and Wikipedia