Growth
For example, during the first half of the 1950s the US GDP growth averaged nearly 5% a year and that performance translated roughly to additional $3,500 per capita (for about 160 million people) during those five years. In contrast, the “slow” GDP growth between 2011 and 2015 (averaging just 2%/year) added about $4,800/capita (for about 317 million people) during those five years, or nearly 40% more than 60 years ago (all totals are in constant-value monies to eliminate the effect of inflation).
But other ancient designs have seen spectacular advances in order to meet the requirements of the industrial age: construction cranes and dockyard cranes are perhaps the best example of this continued evolution.
Although the growth of some artifacts—be they sailing ships or construction cranes—must be traced across millennia, most of the advances have been concentrated in relatively brief growth spurts separated by long periods of no growth or marginal gains.
in the marginPunctuated equilibrium
Reliable historical reconstructions for societies with adequate statistical services go back only 150–200 years.
Height has been always the most appreciated, admired and emulated among the linear variables. This preference is demonstrated in ways ranging from clear correlations between height and power in the corporate world (Adams et al. 2016) to the obsession of architects and developers with building ever taller structures. There is no international organization monitoring the growth of buildings with the largest footprint or the largest internal space—but there is the Council on Tall Buildings and Human Habitat, with its specific criteria for defining and measuring tall buildings (CTBUH 2018).
in the US from 91 m2 of finished area (99 m2 total) in 1950 to about 240 m2 by 2015 (Alexander 2000; USCB 2017)—has resulted in an even faster growth rate for materials used to build and to furnish them.
As a result, new houses built in 2015 are about 2.6 times larger than was the 1950 average, but for many of them the mass of materials required to build them is four times as large.
Most notably, low intakes of fruit and vegetables (the key sources of micronutrients) have been identified as a leading risk factor for chronic disease, but Siegel et al. (2014) showed that in most countries their supply falls below recommended levels. In 2009 the global shortfall was 22% with median supply/need ratios being just 0.42 in low-income and 1.02 in affluent countries.
Exact results are obtained by dividing the natural logarithm of 2 (that is 0.693) by the prevailing growth rate (expressed as a fraction of one, e.g. 0.1 for 10%), but a quite good approximation is dividing 70 by the growth rate expressed in percent. When the Chinese economy was growing at 10% a year, its doubling period was seven years ; conversely, the doubling of components on a microchip in two years implies an annual exponential growth rate of about 35%.