没有什么理论能够很好的解释为何会出现这种改进现象(什么东西?), 只能解释为来自于遗传并进化? 没有上下文,看样子好像在讲动物世界?哈哈

No. There isn't a theory that can fully explain those improvements. That's what it means when it say "No one theory can ...". It might be easier to understand if you look at these examples: "No one person can eat all this food" = "This food cannot be eaten by just a single person" "No one computer can perform all these tasks" = "These tasks cannot be performed by just a single computer" So: "No one theory can explain improvements in performance" = "Improvements in performance cannot be explained by just a single theory" When it says "but the most important factor has been genetics" it means something like this: "theories of genetics have made the largest contribution towards a full explanation." So even though genetics does not fully explain the improvements, it has given us a better explanation than any other theory. Genetics has been the most important factor in our efforts to find an explanation. Does that help?

No, it means that there is no way to fully explain improvements in performance, but that the most important factor in those improvements is genetics. So basically, by looking at genetics you can try to explain performance improvements, because it's too hard to include all possible factors. Something like that.