Not until the beginning of the 20th century did Europe's urban populations finally become self-sustaining: before then, constant immigration of healthy peasants from the countryside was necessary to make up for the constant deaths of city dwellers from crowd diseases.

Not until the beginning of the 20th century did Europe's urban populations finally become self-sustaining: before then, constant immigration of healthy peasants from the countryside was necessary to make up for the constant deaths of city dwellers from crowd diseases.

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.

One person making a wrong decision affects the whole country.

All of our current environmental problems are unanticipated harmful consequences of our existing technology. There is no basis for believing that technology will miraculously stop causing new and unanticipated problems while it is solving the problems that it previously produced.

Why did human development proceed at such different rates on different continents for the last 13,000 years?

The survival rate of Dr Burton's patients approximately doubled the maximum survival rate of conventionally treated patients. Had these findings pertained to a chemotherapy drug instead of IAT, massive amounts of funding would have been allocated to investigate the drug. Once again, the politics of cancer barred a potentially valuable treatment from reaching the public.