What do you characterize as the "explosion" about 50,000 years ago?
Contemporaneous with the second migration out of Africa (that displaced or merged with, depending on who you believe, existing hominin populations), Homo sapiens began using new and far more complex tool technologies 40-50,000 years ago, began using art and burying their dead, began building living structures, and were living in larger and more complex societies. It was a radical transformation that took place in a fairly short period of time and completely changed the way hominins lived and behaved.