Question: the earliest known form of african art is
[{'answer': 'African rock art', 'provenance': [{'wikipedia_id': '331015', 'title': 'African art', 'start_paragraph_id': 17, 'start_character': 61, 'end_paragraph_id': 17, 'end_character': 77, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '331015', 'title': 'African art', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 844, 'bleu_score': 0.9397719915984201, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5990021369041849400}, 'section': 'Section::::History.\n'}]}]