Question: who developed the idea of evolution by natural selection
[{'answer': 'Empedocles', 'provenance': [{'wikipedia_id': '21147', 'title': 'Natural selection', 'start_paragraph_id': 8, 'start_character': 53, 'end_paragraph_id': 8, 'end_character': 63, 'bleu_score': 1.0, 'section': 'Section::::Historical development.:Pre-Darwinian theories.\n'}]}, {'provenance': [{'wikipedia_id': '21147', 'title': 'Natural selection', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 966, 'bleu_score': 0.9865312178338931, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5763251528337011016}, 'section': 'Section::::Historical development.:Pre-Darwinian theories.\n'}]}]