calculated the composite likelihood for present-day human genomic sequences of 3154 individuals. Results showed that human ancestors went through a severe population bottleneck with about 1280 breeding individuals between around 930,000 and 813,000 years ago. ... This bottleneck is congruent with a substantial chronological gap in the available African and Eurasian fossil record.They are trying to say that the Garden of Eden was 900k years ago, and that is when humans started.
I don't see how this much info can be gleaned from DNA, but I did not read the paper.
Humans do have distinct characteristics that are quite different from apes. Not just big brains. The followers of the Aquatic ape hypothesis might say that those 1280 breeders could have lived in water, and undergone rapid evolutionary changes. Wikipedia says "Anthropologists do not take the hypothesis seriously", but the alternatives are not convincing either.
The status of the AAH depends on your philosophy of science. Some say that unless there is some direct evidence for it, such as a fossilized marine community, it is pseudoscience and should not be discussed seriously. Others say that it should be accepted as a working hypothesis as long it explains some evolutionary features, until someone finds a better explanation.