Over the past two million years human body mass first increased and later declined, peaking about 50,000 years ago. This paper sets up a model of natural selection among body types to explain this pattern. Population, technology, and average body mass evolve endogenously and interdependently in such a way that a takeoff in technological progress generates rising population density and resource depletion. This in turn makes large bodies less useful in food procurement, while keeping their metabolism requirements high. The result is a shift in reproductive advantage from big to small bodies and an endogenous reversal of the time trend in body mass.

Long run economic progress in modern Spain is assessed in this paper and its performance placed in European perspective. Over one and a half centuries, income per person rose 15 times. Three main phases can be established: 1850–1950, 1951–1974 and 1975–2000. Spain underperformed in the long run mostly due to its sluggish growth in specific phases of the century prior to 1950. Catching up took place in the late twentieth century, in which the years 1959–74 stand out. Structural change contributed significantly to growth acceleration while lack of exposition to international competition represents a recurrent element of retardation.