Nov 22, 2015

Birthstones

They are gemstone associated with the date of one's birth, the wearing of which is commonly thought to bring good luck or health. Supernatural powers have long been attributed by astrologers to certain gemstones.

The stones now associated with each month have only slight relationship to the ancient beliefs, for the list is tempered by availability and cost. Before mineralogy had progressed to the point of chemical analysis, colour was of greater importance than some of the other physical characteristics, and little distinction was made between emerald and chrysoprase, for example, or between ruby and garnet, or between citrine and topaz. When it came to the ability to heal or bring good luck, the actual stone and the look-alikes were regarded as equally effective. Even the names used in ancient times do not necessarily refer to the stones that go by those names in the 20th century; the sapphire of the Bible is much more likely to have been lapis lazuli than what is now known as sapphire, and adamas (diamond) was probably white sapphire or white topaz. (Britannica Encyclopedia)

January: garnet
February: amethyst
March: bloodstone aqumarine
April: diamond
May: emerald
June: pearl
July: ruby
August: sardonyx
September: sapphire
October: opal
November: topaz
December: turquoise

Nov 15, 2015

The Ice Age

Much of human history unfolded during the dramatic climatic shifts of the most recent ice age which began about 2.5 million years ago. Our ability to adapt to changes in climate has been crucial to the development of civilization but our own activity may now be causing dangerous global warming.

An ice age is a period during which the Earth is cold enough to develop extensive ice sheets. These sheets build up over years when snowfall fails to melt in summer and become blankets of ice thousands of feet thick. Such sheets today cover Antarctica, Greenland, and some high mountains, but during glacial periods (the coldest parts of an ice age), global temperatures drop a few degrees, leading to much larger ice sheets.

At the height of the last glacial period, 20,000 years ago, ice sheets formed over Scandinavia and covered most of Canada and parts of the United States as far south as modern Seattle and the Great Lakes. Great glaciers formed on the Alps and there were ice sheets on the Pyrenees, on the Andes, and on Central Asian mountains and high altitude plateau. Nothing lives on the ice – all life retreats south to places that support some plant growth in summer. We are now enjoying a relatively warm period known as an interglacial. Any ice age fluctuates between these interglacials, which are brief intervals of warmer conditions, and glacial periods - longer stretches of intense cold. When we talk about the Ice Age, we are referring either to the entire cold period (the Pleistocene) or to the last glacial period, which ended between 15,000 and 10,000 years ago.

Nov 8, 2015

Sites of Early Human Fossils and Artifacts

Scientists have discovered the bones and artifacts of early humans in many parts of Africa and Eurasia. The earliest humans, known as australopithecines, lived only in Africa. The modern human genus, Homo, also evolved in Africa, but several middle and late Homo species migrated to Europe and Asia. Early forms of Homo sapiens, or modern humans, lived in Africa and Asia. Only fully modern humans populated the rest of the globe. 
(Encarta Encyclopedia)

Nov 1, 2015

Happiness – according to Aristotle: "is activity of the rational soul in accordance with virtue"

Aristotle's approach to ethics is teleological. If life is to be worth living, he argues, it must surely be for the sake of something that is an end in itself—i.e., desirable for its own sake. If there is any single thing that is the highest human good, therefore, it must be desirable for its own sake, and all other goods must be desirable for the sake of it. One popular conception of the highest human good is pleasure—the pleasures of food, drink, and sex, combined with aesthetic and intellectual pleasures. Other people prefer a life of virtuous action in the political sphere. A third possible candidate for the highest human good is scientific or philosophical contemplation. Aristotle thus reduces the answers to the question “What is a good life?” to a short list of three: the philosophical life, the political life, and the voluptuary life. This triad provides the key to his ethical inquiry.