The NY Times has a profile of economist Robert W. Fogel ("Technology Advances; Humankind Supersizes"). Fogel, along with other historical economists, has worked to document the changes in human stature, mass and health during the last few hundred years. These changes were mostly not evolutionary. That is, it wasn't genetic change that made us bigger, for the most part.
The documentation of these trends has made for a fascinating series of historical studies. The occasion for the profile is the upcoming release of a book by Fogel and colleagues summarizing the decades of work.
To take just a few examples, the average adult man in 1850 in America stood about 5 feet 7 inches and weighed about 146 pounds; someone born then was expected to live until about 45. In the 1980s the typical man in his early 30s was about 5 feet 10 inches tall, weighed about 174 pounds and was likely to pass his 75th birthday.
Across the Atlantic, at the time of the French Revolution, a 30-something Frenchman weighed about 110 pounds, compared with 170 pounds now. And in Norway an average 22-year-old man was about 5 ½ inches taller at the end of the 20th century (5 feet 10.7 inches) than in the middle of the 18th century (5 feet 5.2 inches).
This stuff is tremendously important for human biologists to understand, and the data have become enormously richer in many respects as historical economists have drawn together records about military conscripts, food allowances and disease rates.
The second part of the profile goes into some areas of criticism for Fogel (he focuses mainly on nutrition, other scholars argue for the importance of different causes). I think it is time to integrate a more evolutionary view into the data on recent secular trends. The Framingham study and other longitudinal surveys have demonstrated differential fertility associated with stature in contemporary industrialized societies. Evolution is happening, and does not necessarily go in the same direction as the secular increase in stature. Meanwhile, population differences in stature and other traits owe to a deeper history that includes different causes.