Complex sentence: Modern humans migrated from Africa as recently as 60,000 years ago, and during Upper Paleolithic times they spread throughout Africa, Eurasia, Oceania, and the Americas; and they encountered archaic humans en route during these migrations.
Split into simpler sentences: Modern humans migrated from Africa as recently as 60,000 years ago. During Upper Paleolithic times they spread throughout Africa, Eurasia, Oceania, and the Americas, and they encountered archaic humans along the way during these migrations.