Not a Fact Anymore

Not a fact anymore

Living organisms such as microbes can routinely arise spontaneously from nonliving matter under ordinary present-day conditions.

What we know now

Microorganisms observed in decaying or fermenting material come from pre-existing organisms or their spores. Ordinary biological reproduction follows biogenesis.

Why it changed

Controlled experiments progressively removed hidden sources of contamination. Pasteur's swan-neck flasks allowed air into sterilized broth while trapping dust and microbes, and the broth remained sterile until contamination occurred.

Status
Overturned
Category
Biology
Accepted approximately
Classical antiquity through the 19th century
Changed approximately
17th–19th centuries

This card concerns the historical doctrine that complex organisms or microbes repeatedly arise from decaying matter under ordinary conditions. It does not settle the separate research question of how the first life emerged on the early Earth billions of years ago.

Pasteur’s work was part of a longer experimental history that also included Francesco Redi, John Needham, Lazzaro Spallanzani, Félix Pouchet, and others.

Evidence

Sources and what they establish

Previous belief

  • The middle years 1862–1877 Institut Pasteur

    States that spontaneous generation was widely accepted in scientific circles and describes Pasteur's swan-neck flask experiments.

Historical context

  • Louis Pasteur: a universal legacy Institut Pasteur

    Explains that many believed life arose spontaneously from nonliving matter and summarizes the experiments that refuted the claim.