WHEN, a few years ago, word came that British bird lovers anxious about the decline of the house sparrow had appointed a sparrow tsar, it seemed that the tsar vogue must have reached its zenith.
By the 13th century when the Aztec swept into central Mexico, the once teeming city—which reached its zenith around a.d. 400—had been long since abandoned by its mysterious builders.
"We've been working on this problem for over 10 years and the vaccines we've tried in the past have induced some immune responses but they have not been very effective."
Disease is also a risk, as members of tribal groups that have been contacted in the past have died of illnesses that they have no defence against, ranging from chicken pox to the common cold.
In the Shallows, a book about memory and the Internet, Nicholas Carr said the Web was changing the way we think, read and remember. Humans are hunters and hoarders of information.