Whence does life arise? How, asked early sources, can maggots simply appear in a corpse or oysters just show up on the seafloor? Greek natural philosophers, who thought that all matter held inherent qualities, said life could arise from base matter, given the right conditions. Along similar lines, the ancient Chinese thought bamboo spawned aphids [sources: Brack; Simon].
This idea of spontaneous generation would lead to some delightful experiments, absurd findings and voluminous vitriol spilled by the likes of Voltaire and his 18th-century contemporaries. But the laying of scientific eggs really began in the early 17th century, when Flemish physician Jan Baptista van Helmont said mice would spontaneously arise from a soiled shirt placed in a vessel containing wheat grains, and that scorpions could spawn from a basil-lined brick mold [sources: Brack; Simon]. No word yet on whether a live hamster will issue from a Jamba Juice made with chia seeds and whey protein.
En route to the truth, the science world would detour through two hotly competing theories: Preformationists said all embryos existed, fully formed, in eggs or sperm (which some claimed were like infinite matryoshka dolls reaching back to Adam and Eve), while the epigenesists argued that life arose from other matter but couldn't agree on the underlying force [sources: Alioto; Maienschein].
The resulting arguments were vicious and frequently ludicrous, but efforts at disproving spontaneous generation ultimately drove improvements in scientific rigor and experimental design that helped yield the right answers [source: Encyclopaedia Britannica].