No Two Alike
Look closely at any wild population and no two individuals are identical. These small differences are not flaws — they are the raw material on which natural selection acts.
Every measurable feature — size, colour, beak, bone, behaviour — varies from individual to individual within a species. We tend to overlook it, but the variation is everywhere.
Some of that variation is inherited, passed from parent to offspring. The heritable differences are the ones that matter for evolution.
“These individual differences are of the highest importance for us, for they afford materials for natural selection to accumulate.”
Without variation, selection would have nothing to work on. With it, every population quietly carries the seeds of its own change.
Learn to see variation
See the spread, not the type
A “species” is not one fixed form but a cloud of slightly different individuals. Train your eye on the differences, not the average.
Ask which differences are heritable
Only variation that offspring inherit can drive change. Separate the passed-on from the merely acquired.
- Would this difference show up in the offspring?
Treat variation as opportunity
Where others see noise, see the raw material. Every heritable difference is a possibility that selection can seize.
Individual differences afford the materials for natural selection to accumulate.