It’s darned cold here in Chicago today and it’s on days like this that winter seems interminable. But it’s not and, indeed, isn’t as long as summer.
As every schoolchild knows these days the change in the seasons is caused by the tilt of the earth with respect to the ecliptic (the orbital plane of the earth), i.e. the “obliquity of the ecliptic†and how that affects the sunlight reaching the earth, not the distance from the sun.
In the Northern Hemisphere in the spring and summer that tilt in the earth’s axis exposes the “upper†half of the earth to the sun and days are longer; in the Southern Hemisphere it’s the reverse.
Since the earth’s orbit is elliptical (pictured above) and the sun is not precisely in the center of that orbit, indeed, the earth is actually closer to the sun in Northern Hemisphere winter than in Nothern Hemisphere summer. Here’s something that not every schoolchild knows: because of that elliptical orbit and the position of the sun with respect to that orbit the seasons are actually of different lengths. When the earth is nearer to the sun it moves faster in its orbit; when farther away, slower and, consequently, the seasons vary in length: winter is 89 days long (doesn’t that make you feel warmer?), autumn 90 days, spring 93 days, and summer 94 days.
But wait! There’s more!
Since the earth is actually closer to the sun in the Northern Hemisphere winter than in the Northern Hemisphere summer, more total solar radiation strikes the Northern Hemisphere in the winter than in the Southern Hemisphere in its winter. This tends to moderate the seasons in the Northern Hemisphere somewhat by comparison those in the Southern Hemisphere.
Let’s change subjects.
By something like 11,000 years ago human beings had spread all over the earth except to a few remote islands and Antarctica, from the northernmost part of Alaska to the tip of Tierra del Fuego and the farthest reaches of Siberia to the Cape of Good Hope. And everyplace that the climate permitted horticulture was practiced. Not large-scale agriculture, of course, but non-intensive gardening: throw a few seeds, come back and harvest some time later. I don’t know that people living in the Northern Hemisphere back then were tremendously more advanced (or wealthier) 11,000 years ago than their counterparts in the Southern Hemisphere.
But that changed and by 1500 CE the Northern Hemisphere was enormously more populous (and wealthier) than the Southern Hemisphere and those disparities have largely remained since then.
So, here’s my question. Does the adoption of agriculture in the Northern Hemisphere and the growth in population (and wealth) there derive in whole or in part from the longer growing season in the Northern Hemisphere?
Interesting question, but you have to factor in geography. There’s more landmass and more arable landmass in the northern hemisphere than the southern.
A few years ago, I read a fascinating book by Jared Diamond (which won a Pulitzer) called “Guns, Germs and Steel” which, to a large degree, answers your question. Here’s the wikipedia entry:
http://en.wikipedia.org/wiki/Guns%2C_Germs%2C_and_Steel
I don’t recall Diamond mentioning simple length of growing season.
Certainly geography, IIRC Diamond’s central contention, is also an important factor. But that raises yet another question: to what extent does the same phenomenon i.e. differences in seasonal variance influence geography?
There is a book coming out this year from Gregory Clark, an econ. professor at UC Davis, that might challenge the central role of geographic determinism. Here’s an exceprt from the draft copy available on line:
“Jared Diamond suggested in Guns, Germs and Steel that geography, botany, and zoology were destiny. Europe and Asia got ahead economically, and remained ahead to the present day, because of accidents of geography. They had the kinds of animals that could be domesticated, and the orientation of the Eurasian land mass allowed domesticated plants and animals to spread easily between societies. But there is a gaping lacuna in his argument. In a modern world where the path to riches is through industrialization, why are bad tempered Zebras and Hippos the barrier to economic growth in sub-Saharan Africa? Why didn’t the Industrial Revolution free Africa, New Guinea, and South America from their old geographic disadvantages, as opposed to accentuating their backwardness? And why did the takeover of Australia by the British propel a part of the world which had not developed any settled agriculture by 1800 into the first ranks among developed economies?
The selection mechanisms discussed above can help explain how an initial advantage in Europe, China and Japan, possibly from geography, in establishing settled agrarian societies got translated into a persistent cultural advantage of these societies in later economic competition. Societies without such a long experience of settled, pacific agrarian society cannot instantly adopt the institutions and technologies of the advanced economies, because they have not yet culturally adapted to the demands of productive capitalism.
But history also teaches that even within societies of the same tradition and history, there can be regions or periods of economic energy, and regions and periods of economic torpor. The economic fortunes of the north and south of Britain reversed after World War I, Ireland has become as rich as England after being significantly poorer for at least 200 years, southern Germany has overtaken northern Germany.”
http://www.econ.ucdavis.edu/faculty/gclark/Farewell%20to%20Alms/ftahome.html
Review here: http://www.nytimes.com/2006/11/02/business/02scene.html?ex=1320123600&en=4dc0cd4772070ad2&ei=5088&partner=rssnyt&emc=rss
Honestly, I started to assemble this post before Andy mentioned Diamond.
One of the answers to the question posed in your first comment, PD, is capital investment. The follow-up question then becomes why no capital investment?
The entire book is not on line, but I believe Clark has concluded that its the quality of labor and the institutions supply the answer. I don’t think he necessarily eliminates geographical influences. I think he just finds that aspect far less important than the severe divergences of the world’s economies beginning around 1800.
I haven’t read the book (since I’ve decided to buy it), but I’ve read other things by him and his historical focus has tended to be on Britain and the alternative explanations for its rise as a great power. This would tend to accentuate the role of stable government, low interest rates, low taxes, literacy and service sector growth. There also appears to be a Multhusian element. (Of course, one might note that Britain’s stability may be related to it being an island)
Dave, one other factor is the precession of the equinoxes, which refers to the gyroscopic wobble of the Earth’s axis in approx. 27,000 year cycles. The direction of the axial tilt 13,500 years ago would have been opposite what it is now, placing northern hemispheric winter at the opposite end of Earth’s orbit.
http://en.wikipedia.org/wiki/Precession_of_the_equinoxes
Actually, Piercello, I considered the precession of the equinoxes in preparing this post and there are some very interesting correlations between the variations of the axial tilt over time and the development of agriculture but I thought the post was already complicated enough as it was 😉
My apologies for failing to clearly state my point in my previous comment! In response to the question you posed at the end of the post, I guess it depends on when exactly the northern hemisphere started to outstrip the southern. At your date of 11,000 years ago, due to precession, the south would have had the longer growing season, which is why I brought it up. So if what you are asking is whether the solar shift in relative length of NH/SH growing seasons had something to do with the north’s emerging dominance, then my inexpert answer is “I don’t know, but it sure seems like a plausible component to me!”
Ask me questions about the interacting mechanics of stringed instruments and their performers, and I can be more helpful, if not necessarily concise.
Dave,
Ultimately, I don’t think it’s possible to answer your question definitively. There are so many factors and variables that produced the current state and distribution of wealth and humanity that I doubt it’s possible to make a definitive conclusion about any one variable.
However, you ask about the longer growing season in the Northern Hemisphere? Longer as compared to what? One could argue the mid-latitudes have a near-continuous growing season because there are no cold periods where plant life is dormant. Are you comparing entire hemispheres or specific latitude blocks in each hemisphere?
If comparing the northern to the southern hemisphere in general, you’re bound to get skewed data because of the northern hemisphere’s much larger percentage of land area and therefore much larger fertile land area. The northern hemisphere has 80% of the planet’s total landmass – more if you factor out Antarctica which is uninhabitable. Another way to describe it is the north has ratio of land-to-water of approximately 1 to 1.5; in the south it is 1 to 4. I’m not able to find the specific figures at the moment, but there is a much larger amount of quality arable land in the north.
Finally, when you say:
that’s only partially correct. The ocean in the south acts a a large heat sink and moderates temperatures in the southern hemisphere (also aided by ocean currents that circumnavigate the southern oceans). If you look at temperature comparisons (for example here: http://mclean.ch/climate/hemispheres.htm ) you’ll see that the southern hemisphere has much less temperature variability than the north.
Argh, Andy anticipated my next comment after arriving home and looking at a globe. There is little landmass south of the Tropic of Capricorn comparied to north of the Tropic of Cancer, which is where I think the comparison truly lies. And of the little there is, there are significant mountainous and desert regions that make conclusions impossible.
Unprovable? Or irrefutable?
The equatorial zones have the longest growing season. Not many are doing well.
Diamond’s theories hold up quite well to the point that people begin to form nation-states. After that, national cultural values become paramount, esp as they relate to military prowess and technical capability.
There are three factors, in my opinion, that certainly need to be mentioned, but I think that (pace Andy) there are so many factors that it’s not possible to determine which were key and which were ancillary.
First, there were in effect three cultural paradigms prior to the explosion of wealth in the North (which became noticeable about 2500 years ago): the Classical Western, Aboriginal and Eastern “ways”. The Aboriginal way, prevalent in N. America, Africa, W Asia, northern Europe and Australia, was tribal, largely nomadic, and animist or pantheistic. In the Eastern way, the tendency was towards racial homogeneity, centrally-ruled empires, and a static and benign worldview. In the Classical Western cultures of Greece, Rome, Phoenicia, and so on, government was more geographically-based than tribally or regionally based, and the people formed city-states rather than tribes, and had a dynamic and harsh world view.
These three different cultural paradigms set up each of these groups to react differently to changes in their environments. Essentially, they were differently prepared for the evolutions that would be required of them.
Second, classical Europe was screwed, geographically, despite Diamond’s premise and argument (which is so good it took me years to figure out that he was wrong, and a few years more to determine why he was wrong). Italy was a big peninsula with mountains down the middle of it, leading to small strips of arable land along the coasts. Greece was a rocky, barren place where growing crops other than olives was difficult, and the opportunities for population growth were geographically limited: there was no room to spread out. Phoenicia was surrounded by deserts and mountains, comprising a narrow strip of arable coastal land. And much of that was inhabited by the raving loons of Jews (who were at the time not culturally different from the Arabs then and now; it was the Jews’ time in Europe that changed them much for the better). By comparison, the rest of Europe, Africa South of the Sahara, and Asia were blessed with much arable land, large huntable forests and much more forgiving climates.
This drove the classical Europeans in a few directions. Politically, they had developed city-states, the Republic, the Democracy, rule of law, individual and alienable property ownership (this is a big one) and a few other useful institutional innovations. Intellectually, their forced reliance on their wits to survive developed into logic, the primacy of reason, engineering, and eventually the concept of science. Socially the classical Europeans developed mobile and flexible societies where you could rise based on merit. More or less, a large part of what developed in classical Europe was curiosity and individualism. These are but examples; there are many more.
By contrast, Aboriginal societies did not develop new social or political institutions, and did not develop intellectually. I suspect that this was largely due to the fact that they didn’t have to: their way of life was already well-suited to their quite benign (by comparison) environments. Individualism was less useful than tribalism, and the real developments made by aboriginals was in art and spirituality. The East Asians developed artistically and intellectually, but in very rigidly defined ways. Similarly, social and political arrangements were rigid, formal, and tightly governed. More, East Asians were inventive but not curious: they would make an advance, or note something interesting, but never really follow up. (Consider that the Chinese invented fireworks and the Europeans turned that into weaponry.)
Finally, these developments (after the interregnum of the Dark Ages, where the aboriginal North almost overwhelmed the Classical European culture) were spurred into Renaissance at just the time that Europe had come through the Black Death. One of the main effects of the Black Death is that it concentrated the wealth of the poor, which had a huge influence on the end of feudalism, and another is that those who survived found themselves once again thrown into an era where (this time due to lack of cheap labor) they had to rely on their wits to survive. Coincidentally, at just this time, the Arab preservations of Greek and Roman knowledge and the remnants in the monasteries came onto the scene, providing the knowledge and modes of thought that the Europeans needed to solve their labor problems (among other problems they had). The result was the Enlightenment, probably the pinnacle of human philosophical and cultural achievement to date, even though it also produced Rousseau.
The various evolutionary pressures exerted on Europeans at key times, and their acculturated responses to those pressures conditioned by scarcity, deprivation and disease (an area where Diamond had a real point, certainly), were far more important, I think, to the rise of the wealthy West than were the length of the growing season or the relative amounts of land. And note that where Western institutions and modes of thought have taken hold (America, Australia, China, Japan, S. Korea and so on), wealth has followed quickly. Where classical Western institutions and modes of thought have not taken hold, life has remained nasty, poor, solitary, brutish and short. (Key examples: India, S. Korea).
Note, too, that post-Enlightenment Western cultural innovations, such as Marxism, have tended to be deal-killers: take Cuba as an example, or compare North to South Korea or China before the 1980s to Taiwan.