FILE -- A humpback whale surfaces while feasting on a school of menhaden, or bunker, fish, in the Atlantic Ocean off the coast of New Jersey, Sept. 7, 2018. A study published in Science Advances reports that the loss of some genes in the common ancestor of whales and dolphins allowed them to shed features that would have been liabilities beneath the waves, which may have contributed to the survival of future generations. (Dave Sanders/The New York Times)