We "know" that Adam's first son was born when Adam was 130 years old, because the bible tells us so.
Genesis 5:3 And Adam lived on for a hundred and thirty years. Then he became father to a son in his likeness, in his image, and called his name Seth.
So if Adam was around 30 years old when Eve was created (which I haven't figured out how anyone can know that) then it took one hundred years for these almost perfect humans to create a child? So how did that "be fruitful and fill the earth" thing work out for em? Looks like they were slow learners.