The Science Book

156

OMNE VIVUM

EX VIVO—

ALL LIFE

FROM LIFE

LOUIS PASTEUR (1822–1895)

M

odern biology teaches

that living things can

only arise from other

living things by a process of

reproduction. This may seem self-

evident today, but when the basic

principles of biology were in their

infancy, many scientists adhered to

a notion called “abiogenesis”—the

idea that life could spontaneously

generate itself. Long after Aristotle

claimed that living organisms

could emerge from decaying

matter, some even believed in

methods that purported to make

creatures from inanimate objects.

In the 17th century, for example,

Flemish physician Jan Baptista

von Helmont wrote that sweaty

IN CONTEXT

BRANCH

Biology

BEFORE

1668 Francesco Redi

demonstrates that maggots

arise from flies—and not

spontaneously.

1745 John Needham boils

broth to kill microbes, and

believes that spontaneous

generation has occurred

when they grow back.

1768 Lazzaro Spallanzani

shows that microbes do not

grow in boiled broth when

air is excluded.

AFTER

1881 Robert Koch isolates

microbes that cause disease.

1953 Stanley Miller and

Harold Urey create amino

acids—essential to life—in

an experiment that simulates

origin-of-life conditions.