Contrary to popular belief science is more than controlled experiments that are conducted in laboratories.
Has a bear ever involved into a lion? How has an ape evolved into a human?
After scientists and science enthusiasts spent millions on searching the missing link and pouring thousands of manhours into it, eventually, we have discovered that humans have not evolved from existing ape species. It is just that millions of years ago humans and primates were the same species. There has never been a species that linked humans to existing ape species.