There is a category of human variation that is essentially invisible, because it concerns something nobody can observe in anybody else and nobody has reason to compare.
Ask two people…
Most descriptions of the ocean concern its surface, which is understandable, since that is the part anybody sees.
The surface is a thin film on top of something much larger.…
There is an assumption that things used routinely are understood, and it does not hold in general.
A great many effective interventions were established empirically — somebody noticed that something…
Everything below comes from one thing: the axis the Earth spins on is not perpendicular to the plane it orbits in. Every seasonal phenomenon anywhere is a consequence of that…
The distinction that organises the whole subject is between comparing and measuring. A balance compares; a scale measures a force. Almost every difference between weighing devices follows from which one…
The organising fact is that a plant has several parts, and if you consistently select for one of them getting bigger, you eventually get a vegetable that is mostly that…