It’s no secret humans have been having sex for millennia — but recently discovered cave art suggests they were doing it in the Americas much earlier than many archeologists believed.

A new exhibit in Brazil showcases artifacts dating as far back as 30,000 years ago — throwing a wrench in the commonly held theory humans first crossed to the Americas from Asia a mere 12,000 years ago.

The 100 items on display in Brasilia, including cave paintings and ceramic art, depict animals, ceremonies, hunting expeditions — and even scenes from the sex lives of this ancient group of early Americans....