Figure 2.

Skills ontogeny reflecting pupil boost (θ) and teacher handicap (φ). (a) Pupil benefit: a pupil at age 10 is taught for 10 years and increases rate of skill acquisition by the boost (0 ≤ θ ≤ 1), thereby reducing age at skill mastery. (b) Teacher cost: A teacher suffers a loss in production during the 10 years of teaching by a proportion φ of baseline production. Notice for a given φ that absolute production loss is lower when teaching occurs later in life (e.g. when b = 50 instead of when b = 20). Inset values show the lost production across the 10 years of teaching, where 1.0 represents 1 year of peak production. (Online version in colour.)