In this case on what we have covered so far this term and what you make of the implications. To help you, here's a brief recap of the highlights to date. See if they tally with your own understanding of the themes and ideas we've looked at so far:

a. The origins of life on earth date back possibly 4 billion years or so; our own distant ancestors, early squirrel-like primates, probably appeared on the scene about 65 million years ago; hominids -- the descendants of those early primates who branched off from a common ancestry with gorillas and chimps -- date back possibly 4-6 million years, maybe more. Our more direct ancestors, such as Homo habilis, appeared roughly 2.5 million years ago. Homo sapiensis more recent, appearing in the fossil record roughly 200,000 years ago.

b. What does this mean? Two things, at least. One, as a distinct species, humans occur very late in the history of the earth, the outcome of millions of years of evolution in which small advantages were selected and passed on from one generation to the next, until, over time whatever it is that makes us unique could be identified as a single species. Second, those small advantages - bi-pedalism, stereoscopic vision, large brains, opposable thumbs, language, etc. -- were not absolute (i.e. superior in all circumstances), but relative (i.e. better adapted to specific environments). That we have emerged as a truly global species, cornering an immense share of the world's energy supply, needs explaining; it cannot be assumed to be inevitable.

c. Our ability to adapt to new circumstances and new environments, to the extent that it looks like that we control those environments, may be our distinguishing feature. In turn, of course, we have changed even as we adapt to our environment. Leaving Africa c. 100,000-50,000 years ago, humans slowly moved around the world into ever new environments. Those who failed to adapt, died. Those who did adapt, survived, and passed on their genes to the next generation, and so on. As we've discussed several times, you don't have to be the fittest to survive, just fitter than the next in line.

d. In the context of life on earth, our dispersal around the world was rapid. In just a few ten thousand years, humans could be found everywhere except for Antarctica. Again, though, there was no master plan to colonize the planet; we simply moved on whenever environmental factors determined it was better to do so than stay put.

e. For the vast majority of our history, we survived by foraging. We came up with inventive ways of limiting how much work this would take -- spears, axes, bows and arrows, nets, etc. -- but still we remained a mostly nomadic species. Only in the past 10,000 years did we cross the threshold to a more sedentary (fixed) existence; slight growth in population made it necessary to innovate, to develop more efficient ways of securing enough food from a fixed amount of land, and over thousands of years agriculture emerged. This meant more work, poorer diets, and earlier death, ironically, but the collective benefits of agriculture were too great to abandon; more to the point, once established, it was all but impossible to return to a foraging lifestyle without decimating the new and larger population.

f. Complexity, coercion and conquest -- these are the hallmarks of civilization. Agricultural societies were larger and therefore more complex than small roving nomadic bands; it was necessary to establish some sort of hierarchy, laws, rules, government, etc. to keep the new tribes together. Agricultural surpluses (plus specialization) made trade possible (and so money, eventually) and some form of accounting (i.e. writing) essential. Fixed populations were doubtless tempting targets for raiders, but the larger populations, ability to extract tribute (including military service) from surrounding areas, and later the building of city walls always gave the settled peoples an advantage. This led, by c. 3500 BC, to the first recorded civilization, the Sumerians.

g. Expansion seems to be the 4th hallmark of civilizations. Decline means extinction; standing still is rarely possible in the long run. But as we saw, all ancient civilizations eventually overextended themselves, in one way or another outgrowing their ability to maintain environmental sustainability. The Malthusian Cycle is one way of understanding this apparently unavoidable fate.

h. The Middle Ages cover the 1000 or so years between the Fall of Rome (c. 500 AD) and the Renaissance (c. 1400-1500) that claimed to mark the revival of civilization, but this lengthy period, as we saw, was also one in which considerable advances in technology and farming took place. However, the success of these advances was, once again, to cause a rise in population that, by the 1300s, had outstripped the available supply of food. The Black Death of the 1340s therefore hit a Europe already weakened by famine; and in wiping out maybe 30% of the population, it overturned all the political, social and economic foundations of the Middle Ages and paved the way for a new period in Europe's (and the world's) history.

i. This brings us finally to the European outthrust in the 1400s and 1500s, as they sought a westward route to Asia across the Atlantic. The Vikings had done this already in 1000, but left little cultural legacy, Not so Columbus in 1492. When he landed in the Caribbean that year, Columbus and his crew initiated an exchange (of plants, animals, disease and, eventually, population) that changed the world forever. We still live in the shadow of Columbus. As I suggested, depictions of Columbus as either hero (for 'discovering' America) or villain (for starting a contact that would all but wipe out indigenous people in the Americas and lead to the abominable Atlantic slave trade) perhaps miss the point as far as our course is concerned. What happened in 1492, from the larger perspective, is that humans finally completed the trek they had begun 100,000 years earlier. In essence, the meeting of Columbus and the natives of San Salvador (and elsewhere) was a delayed family reunion -- that neither recognized the other is not the point; what is, is that as a species we had finally come full circle.