Experiments on Plant Hybridization
Gregor Mendel · 1866
"Traits are passed from parent to offspring as discrete, countable units — not as a smooth blend of parental characteristics — following statistical ratios predictable enough that Mendel derived the basic laws of inheritance from pea plants alone, decades before genes or DNA were known to exist."
An Augustinian friar spent eight years cross-breeding pea plants in a monastery garden and, without knowing what a gene physically was, worked out the mathematical rules of inheritance that genetics is still built on.
Mendel tracked seven distinct pea plant traits (seed shape, flower color, and others) across generations and found offspring didn't blend parental traits, as the dominant theory of the time assumed — instead, traits appeared in predictable ratios (like the famous 3:1 ratio in second-generation crosses), implying each parent contributes a discrete, particulate unit of inheritance for each trait, one of which can mask the other (dominant vs. recessive). His law of segregation (each parent's two copies of a trait separate, passing only one to each offspring) and law of independent assortment (different traits are typically inherited independently of each other) were derived purely from breeding statistics — the physical basis (genes on chromosomes, later DNA) wouldn't be understood for decades. His 1866 paper was largely ignored during his lifetime and only recognized as foundational around 1900, when other researchers rediscovered the same patterns independently.
What did Mendel's pea plant experiments reveal about inheritance that contradicted the prevailing theory of his time?
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The explanation above is written with AI assistance. These are the originals — go to them to check it.
- Experiments on Plant Hybridization (Mendel, 1866) overviewGregor Mendel / Wikipedia
Nothing in Biology Makes Sense Except in the Light of Evolution
"By the mid-20th century, genetics (Mendel's discrete units) and natural selection (Darwin's mechanism) had been fused into a single coherent framework — the Modern Synthesis — that made evolutionary theory the organizing principle underneath every other branch of biology."