Complex sentence: However, older sites dating back to 20,000 years ago have been claimed, and some genetic studies estimate the colonization of the Americas dates from between 40,000 to 13,000 years ago.
Split into simpler sentences: However, older sites dating back to 20,000 years ago have been claimed. Some genetic studies estimate the colonization of the Americas dates from between 40,000 to 13,000 years ago.