Question: what were the cultural exchanges to the americas from africa
[{'answer': 'Columbian Exchange', 'provenance': [{'wikipedia_id': '622746', 'title': 'Columbian exchange', 'start_paragraph_id': 3, 'start_character': 110, 'end_paragraph_id': 3, 'end_character': 128, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '622746', 'title': 'Columbian exchange', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 702, 'bleu_score': 0.5726193662773591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2378223843378308078}, 'section': 'Section::::Abstract.'}]}]