Biology / Unit 8 Bio 1643 short lesson, about 20 seconds
Natural Selection Defined
Captions available
The idea
Natural selection, per Unit 1's Bio 0056, is the differential survival and reproduction of individuals whose heritable traits better suit their environment.
In practice
Individuals whose inherited traits improve survival and reproduction leave more descendants, so those traits become more common next generation.
Where people slip
"Survival of the fittest" misleads if read as only the strongest or fastest — fitness means reproductive success, not physical dominance.
Your place on the trail
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