Question: when were pigeons first used to carry messages
[{'answer': '3000 years ago', 'provenance': [{'wikipedia_id': '206964', 'title': 'Homing pigeon', 'start_paragraph_id': 10, 'start_character': 71, 'end_paragraph_id': 10, 'end_character': 85, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '206964', 'title': 'Homing pigeon', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 693, 'bleu_score': 0.7610450125864271, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3600357960132659179}, 'section': 'Section::::History.\n'}]}]