I suspect it's rather that conditions were such that food had also become available elsewhere.
Though they're easy to imagine as the Hebrew exodus where a whole people travel to another country, in reality the migrations were for most of the time more like "Why don't you and Lucy go over there, you'll have more time for yourself that way.
With "over there" being 100 meters away. that'll easily get people from Africa to Norway in less than 2 million years.
Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain