Asked by: John Haines, by email
Long-term memory is handled by parts of the brain that are evolutionarily quite ancient. The more primitive a sensory impulse is, the more readily it transfers to long-term memory. Faces are a much older form of identity than names.
Our brains have evolved a particular sensitivity to the subtle variations in the human face because it’s a very useful marker point – high up, facing forward, unobstructed by limbs and nearly always unclothed. Remembering shoulders or belly buttons is much harder. Names are harder still because the language-processing part of the brain is a very recent addition.