In Britain, "pig" refers to any member of the class of domestic swine, but the United States uses the term when referring only to younger swine not yet ready for market and weighing less than 82 kilograms (180 pounds).

Simply because they are genetically engineered does not make it any more likely for plants to become an invasive or persistent weed, according to a decade-long study published in the journal Nature.

Recent breakthroughs in technology have made it possible that high-definition digital video cameras are able to capture material with a degree of fidelity that nearly compares to 35-millimeter film and to project it digitally in theaters with no resulting loss of image quality.

Many environmentalists, and some economists, say that free trade encourages industry to relocate to countries with ineffective or poorly enforced antipollution laws, mostly in the developing world, and that, in order to maintain competitiveness, rich nations have joined this downward slide toward more lax attitudes about pollution.

To help counteract the adverse effects of trout stocking on the amphibian populations in certain mountain lakes, biologists are recommending cutting back on trout stocking on the part of some states and even their being removed from some popular fishing lakes.

A study of food resources in the North Pacific between 1989 and 1996 revealed that creatures of the seabed were suffering from dwindling food supplies, possibly resulting from increasing sea surface temperatures during the same period.

A decade after initiating the nation's most comprehensive and aggressive antismoking program, per capita consumption of cigarettes in California declined from over 125 packs annually per person to about 60, a drop more than twice as great as in the nation as a whole.

Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.

In some species of cricket, the number of chirps per minute used by the male for attracting females rise and fall in accordance with the surrounding temperature, and they can in fact serve as an approximate thermometer.

Unlike frogs that metamorphose from tadpoles into adults within a one-year period, it takes three to four years for the mountain yellow-legged frog of the Sierra Nevada to reach adulthood, and so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter.