Based on the analysis, it is very likely that the 7 stars were more distinctly visible but then gradually became harder and harder to see upto about 30-40k year

Based on the analysis, it is very likely that the 7 stars were more distinctly visible but then gradually became harder and harder to see upto about 30-40k years ago. So cultures started making stories for why it disappeared. The fact that the stories of why the seventh sister disappeared seem different across cultures may possibly indicate the cultures had already separated when that happened.