GENETICS

The Monk Who Counted Peas

1866 CE

History · Contemporary · Holocene · Meghalayan

In a monastery garden in Brno, Gregor Mendel grew some ten thousand pea plants over eight years, tracked seven contrasting traits through their crosses, and found arithmetic where everyone else saw blending: traits pass as discrete units, in ratios. He published in 1866 and was ignored for a third of a century. In 2025, genomics closed the circle, pinning down the exact DNA changes behind all seven of his traits, from flower colour to the fasciated stem.

Why it matters

Mendel supplied the half of the modern synthesis that Darwin lacked: a mechanism by which variation persists instead of diluting away. His deeper innovation was method, counting and ratios brought into biology, so revolutionary that his contemporaries did not recognize it as biology at all. Every genetic result on this timeline, from lactase to ancient genomes, speaks his language of alleles.

Dating & uncertainty

Mendel read his results in 1865 and published them in 1866; the world caught up in 1900, when his laws were rediscovered. The postscript is recent: genomics has now identified the molecular lesions behind all seven of his pea traits, down to the deletions and insertions, and the long controversy over his 'too good' ratios is judged not to touch his lasting contribution.

Sources

1. Mendel (1866) · Experiments on plant hybrids, read to the Brünn Natural History Society. Institutional source: original German text at the Biodiversity Heritage Library, accessed 2026-08-30.
2. Feng et al. (2025), Nature · Genomic and genetic insights into Mendel's pea genesdoi:10.1038/s41586-025-08891-6
3. Sussmilch et al. (2022), Plant Physiology · Mendel: from genes to genomedoi:10.1093/plphys/kiac424

Our species’ history as one day

23:59:1643.9 s before midnight

if the 315,000 years of Homo sapiens were compressed into a single day