I recently ran across this essay, "How Fast and How Far Can China's GDP Grow?" from a few years ago, which included the following observation:
"An international comparison shows that the time needed for doubling per capita GDP is 58 years in England during the period of 1780-1838, 47 years in the United States during 1839-1886, 34 years in Japan during 1885-1919, and 11 years in Korea during 1966-1977. China has set a new record--per capita GDP in China doubled within only 9 years between 1978 and 1987, and doubled again in another 9 years between 1987 and 1996."
These figures fit into the broader picture that has emerged from the economic literature in the past two centuries trying to figure out why the last two hundred years have seen such rapid economic growth in countries across the world. And it seems probable that another country--India, an African nation--could match China's record of nine years or maybe even break it.
Expanding our purview, the astounding story of economic growth in the last two hundred years makes me wonder: (1) are we now in a permanent period of growth, and (2) what could that mean for human evolution, on multiple levels?
The first question will likely generate the most controversy, but it's really the less interesting one. It is impossible to definitively say we have (or have not) entered an era of unending growth. Things can always happen to derail such hope, and likely will happen. (If you believe the theory that the relative percentage of young men in a country determines that country's propensity for military aggression, then China's gender imbalance should worry you. Nb: I am not endorsing this theory.)
Likewise, growth remains absent in many countries--Paul Collier's recent book, The Bottom Billion, offers a very well-measured look at intractable stagnation.
Nonetheless, it's certainly at least possible to contemplate a future of continued growth: we know we can achieve sustained growth and, according to Robert Lucas, that's no longer the question economists should address. Again, I am not asserting that we have "solved" for economic growth and that the future is a limitless cornucopia. I'm simply saying that, given our experience over the last two centuries, it's at least a possibility that should be considered.
Now, the more interesting question is what effect, if any, sustained economic growth has had and will continue to have on human evolution. After years of controversy among biologists, it seems to nearly be settled that selection and adaptation can occur on multiple levels: genetic, cellular, epigenetic, individual, social, cultural. And it seems to me that it would strain credulity to believe that economic growth does not have an impact on human evolution.
For thousands of years, humanity enjoyed little to no economic growth in terms of living standards. To be sure, there were technological advances: fire, geometry, the wheel, the saddle, soap, the odd proto-machine here and there, etc. (By the way, I'm pretty sure soap was an innovation of those much-maligned Huns.) Some work has been done on the multiple levels of evolution involved in large historical events.
So when in desultory fashion humanity did begin to experience sustained economic growth, doesn't it make sense that it somehow affected the course of human evolution? And, at least for emergent levels of social and cultural evolution, what does that mean for the future?
Robert Fogel, inter alios, has done fantastic work charting changes in human physiology over time. So we know, then, that humans do adapt, in relatively rapid time, to changes in diet and lifestyle. Aside from the work of Fogel and the slightly related work of Robert Gallman and others, I'm not aware of much scholarship that is oriented toward the question of how economic growth has affected human evolution. (Michael Kremer published an interesting paper, "Population Growth and Technological Change: One Million B.C. to 1990," in The Quarterly Journal of Economics in 1993, showing that technological change increased at a constant rate with population growth until about 1800.)
This shouldn't be a surprise: we've never really had a reason to consider it because sustained economic growth wasn't part of the fabric of human reality for most of our existence. Let's take the conventional time period of 200,000 years ago for homo sapiens: the period of sustained economic growth represents about one tenth of one percent of humanity's time as a separate species. To narrow it even further, if we take the last fifty years as the era during which growth really spread across the world, then it's only about 0.025 percent.
In other words, economic growth--in terms of improved living standards--is pretty new. So first we would have to wrap our brains around the fact that evolution could occur on that short of a time scale. If we consider evolution on multiple levels, however, this isn't as hard. (And Fogel's work helps here.) Then we would have to come to grips with the fact that humanity is evolving right now, and that the future holds "endless forms most beautiful" for humanity writ large, particularly (our interest here) in terms of social, cultural, economic, and institutional forms.
Update: A 2002 article in The Quarterly Journal of Economics, "Natural Selection and the Origin of Economic Growth," by Oded Galor and Omer Moav, is on point here, but looks at the reverse question: what role did natural selection play in human evolution in creating the growth acceleration of the last two hundred years?
Nb: I am in no way endorsing any notion that economic growth's effect on evolution has somehow caused different groups of people to evolve "better" or "higher" than others.