The molecular clock hypothesis, first advanced in 1965 by Linus Pauling (1901-1994) and Emile Zuckerkandl, suggests that the mutation driven changes (substitutions) in the amino acid sequences of proteins has a characteristic substitution rate that is...

Circadian rhythms are fluctuations in biochemical and behavioral activities that occur over a period of about 24 hours. These activities are not simply a light-dark reaction, but are generated by an internal timekeeping mechanism called the circadian...

The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics to date when two species diverged. Elapsed time is deduced by applying a time scale to the number of molecular differences measured between the species' DNA...

Five Bulgarian nurses and a Palestinian doctor were convicted and sentenced to death by a Libyan court Tuesday on charges they deliberately infected hundreds of children with the AIDS virus. The verdict can be appealed.Judge Mahmoud Hawissa read out the verdict at a seven-minute hearing...

More than a hundred species of tiny land-breeding frogs in the Caribbean evolved from a single South American species that probably hitched a ride on a raft of vegetation and washed up on an island beach, according to scientists who spent decades collecting tissues from...

A court convicted six foreign health workers Tuesday on charges of deliberately infecting 400 children with the AIDS virus and sentenced them to death, setting off shouts of joy in Tripoli.The verdict, which will be automatically referred to Libya's Supreme Court, drew quick condemnation from...

A court convicted five Bulgarian nurses and a Palestinian doctor Tuesday of deliberately infecting 400 children with HIV and sentenced them to death, despite scientific evidence the youngsters had the virus before the medical workers came to Libya.The United States and Europe reacted with outrage...