[A]s a graduate student at Columbia University, I remember the a priori derision of my distinguished stratigraphy professor toward a visiting Austral… - Stephen Jay Gould

Skepticism is the agent of reason against organized irrationalism — and is therefore one of the keys to human social and civic decency.

Siphonophores do not convey the message—a favorite theme of unthinking romanticism—that nature is but one gigantic whole, all its parts intimately connected and interacting in some higher, ineffable harmony. Nature revels in boundaries and distinctions; we inhabit a universe of structure. But since our universe of structure has evolved historically, it must present us with fuzzy boundaries, where one kind of thing grades into another.

All life on earth - everything from bacteria to mushrooms to hippos - shares an astonishing range of detailed biochemical similarities, including the structure of heredity in DNA and RNA, and the universal use of ATP as an energy-storing compound. Two possible scenarios, with markedly different implications for the nature of life, might explain these regularities: either all earthly life shares these features because no other chemistry can work, or these similarities only record the common descent of all organisms on earth from a single origin that happened to feature this chemistry as one possibility among many.