An organism is never only the result of its immediate circumstances.
Its organisation carries older histories.
A bird's wing reflects more than the environment in which the bird is flying now. Its structure is the outcome of inherited differences accumulated through generations of selection.
The same is true of the eye, the skeleton, the immune system, the nervous system.
Each is a present arrangement shaped by many past conditions.
Evolution therefore does not simply add adaptations one at a time.
It layers history.
A new variation arises within an organism already carrying an enormous inheritance. Selection acts upon that existing organisation. What survives becomes the starting point for further change.
The future inherits a past that has already been reorganised by earlier histories.
This makes evolution cumulative.
A lineage does not begin again with every generation.
It carries forward an organisation that has already been shaped by previous generations, and subsequent selection works upon that inherited organisation.
History becomes a condition for further history.
We can now see why the genetic “book” is so unlike an ordinary book.
A book has pages that can be read independently.
An organism has histories that interact.
A new adaptation may depend upon structures inherited from much older adaptations. A feature shaped for one function may later become the basis for another.
The present therefore contains not simply traces of the past, but possibilities created by earlier traces.
This is one reason evolution can produce such extraordinary complexity without foresight.
Natural selection does not need to know where a lineage is going.
It modifies what is already there.
The future works with the historical organisation it inherits.
And that means an organism is, in a profound sense, a record of what its lineage has been able to carry forward.
Not a perfect record.
Not a conscious record.
Not even necessarily a record of the environments themselves.
It is a record of which consequences of those environments became embodied in continuing lineages.
The organism is history made living.
And once history can accumulate in this way, a new question appears:
How much of an organism's present organisation can be understood as a solution to problems that no longer exist?
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