The southward advance of native African farmers with Central African crops halted in Natal, beyond which Central African crops couldn't grow - with enormous consequences for the recent history of South Africa.
We're uncomfortable about considering history as a science. It's classified as a social science, which is considered not quite scientific.
We study the injustices of history for the same reason that we study genocide, and for the same reason that psychologists study the minds of murderers and rapists... to understand how those evil things came about.
Although native Africans domesticated some plants in the Sahel and in Ethiopia and in tropical West Africa, they acquired valuable domestic animals only later, from the north.
Twenty years ago, you might have been pessimistic and said there's no hope. But these days, some of our very biggest companies are acting remarkably cleanly. And in some cases, although not all cases, the CEOs are the driving forces behind that.
I'd rather spend my leisure time doing what some people call my work and I call my fun.
Lest those islands still seem to you too remote in space and time to be relevant to our modern societies, just think about the risks... of our increasing globalization and increasing worldwide economic interdependence.
The rate of human invention is faster, and the rate of cultural loss is slower, in areas occupied by many competing societies with many individuals and in contact with societies elsewhere.
Introspection and preserved writings give us far more insight into the ways of past humans than we have into the ways of past dinosaurs. For that reason, I'm optimistic that we can eventually arrive at convincing explanations for these broadest patterns of human history.
Native Americans had only stone and wooden weapons and no animals that could be ridden. Those military advantages repeatedly enabled troops of a few dozen mounted Spaniards to defeat Indian armies numbering in the thousands.
Starbucks goes to a great effort, and pays twice as much for its coffee as its competitors do, and is very careful to help coffee producers in developing countries grow coffee without pesticides and in ways that preserve forest structure.
I've always been interested in a lot of things, and a lot of things at the same time, and I always tried to explain them to myself. I ask a lot of questions.
Thousands of years ago, humans domesticated every possible large wild mammal species fulfilling all those criteria and worth domesticating, with the result that there have been no valuable additions of domestic animals in recent times, despite the efforts of modern science.
Technology causes problems as well as solves problems. Nobody has figured out a way to ensure that, as of tomorrow, technology won't create problems. Technology simply means increased power, which is why we have the global problems we face today.
Infectious diseases introduced with Europeans, like smallpox and measles, spread from one Indian tribe to another, far in advance of Europeans themselves, and killed an estimated 95% of the New World's Indian population.
No government is here forever. And there are other forces - the most potent force in our society, in fact, big business - doing good for the environment.
All human societies go through fads in which they temporarily either adopt practices of little use or else abandon practices of considerable use.
Eurasia ended up with the most domesticated animal species in part because it's the world's largest land mass and offered the most wild species to begin with.
Federal elections happen every two years in this country. Presidential elections every four years. And four years just isn't long enough to dismantle all the environmental laws we've got in this country.
Take air quality in the United States today: It's about 30 percent better than it was 25 years ago, even though there are now more people driving more cars.
I decided that now is the time to start doing the things that really interest me and I find important. It was in the 10 years of the MacArthur grant that I began working on my first book... and I began putting more work into environmental history.
The main thing that gives me hope is the media. We have radio, TV, magazines, and books, so we have the possibility of learning from societies that are remote from us, like Somalia. We turn on the TV and see what blew up in Iraq or we see conditions in Afghanistan.
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