Survival of the Fittest Does Not Mean the Strongest
Fitness is being in good physical condition, and being suitable for a purpose. Biology uses the second sense, which is why the famous phrase is so often misread.
Fitness has two senses that pull apart. One is physical condition. The other is suitability — fitness for purpose. Biology means the second: *survival of the fittest* is about which organisms fit their environment best, not which are strongest. The phrase was coined by Herbert Spencer, and Darwin adopted it later, to his cost.
- Physical condition. *He trains for general fitness.*
- Suitability for a purpose. *Fitness for purpose.*
- Reproductive success (biology). *Evolutionary fitness.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | fitness | A fitness test. |
| Adjective | fit | Match fit. |
| Comparative | fitter | Fitter than last year. |
| Superlative | fittest | The fittest survive. |
| Opposite | unfit | Unfit for duty. |
How it is used in a sentence
- She failed the fitness test by two seconds.Physical sense.
- Goods must be of satisfactory quality and fit for purpose.A consumer-law formula.
- Fitness in biology is measured by offspring, not muscle.The technical sense.
Components of physical fitness
- Cardiovascular endurance — how long you can keep going
- Muscular strength — how much force you can produce
- Muscular endurance — how long you can repeat it
- Flexibility — range of movement at a joint
- Body composition — the proportions of muscle, fat and bone
From *fit*, a word of uncertain origin recorded from the fourteenth century meaning suitable or well matched. The physical sense is the newer one, and it only became dominant in the twentieth century.
Who said survival of the fittest?
Herbert Spencer, in 1864, after reading Darwin. Darwin adopted the phrase in a later edition of On the Origin of Species.
What does *fit for purpose* mean?
That something does the job it was sold or designed for. In consumer law it is a legal standard, not a compliment.