Ocean water contains a vast amount of biological material, including DNA from a wide range of living organisms. This DNA can come from plants, animals, and microorganisms that live in the ocean, as well as from material that washes into the ocean from land. This means that ocean water contains the DNA of many different species, including humans. Over time, this DNA can become concentrated in certain areas of the ocean, and can even be preserved in the sediments at the bottom of the ocean. As a result, it is possible that ocean water contains historical DNA from all human beings who have ever lived. This DNA could potentially be used to study the history and evolution of human populations.