Many UFO enthusiasts spread the "urban myth" of secret US government experiments on aliens, an idea reinforced by the movie Independence Day. Does a cover-up, however, make sense when, under the inspiration of atheists like the late Carl Sagan, the US government has spent millions of taxpayers' dollars listening "out there" for signs of intelligent extraterrestrial life?
Many other evolutionary humanists, like Sagan, passionately believe that intelligent life has evolved "out there" in addition to the life on Earth, and would pounce on any hard evidence for this idea. Consider the media frenzy about the "life in Mars rock" fiasco. To imagine that a much more exciting discovery would be kept secret for decades defies credibility.
Sign of Design: The thousands of vertebrate species on the ark emerged into a world with large numbers of empty ecological niches. They must have split many times into new species in the first few centuries thereafter, as the bear population, for example, gave rise to polar bears, grizzlies, giant pandas, and more.