PENGHU CHANNEL, TAIWAN—Surprising new research suggests that Denisovans, an extinct species of hominin, were much taller than their Pleistocene contemporaries, Science reports. Denisovans were related to Neanderthals but genetically split from them around 550,000 years ago. They came to inhabit much of Asia, from Siberia to China. Two decades ago, two mysterious and ancient leg bones were dredged up from the seafloor of the Penghu Channel off th…