I’ve always considered the sweet potato in Polynesia to be the “smoking gun” when it came to Pre-Columbian contact between the Americas and the “Old World”.
Now, genetic evidence appears to back up this theory. The article below concludes:
“[We] find strong genetic evidence for pre-Columbian human trans-Pacific voyaging contact (at the turn of the twelfth century), contemporaneous with the Polynesian voyages of discovery in the remote eastern Pacific.“