The two goats were probably domesticated independently, one in the Middle East and the other in Pakistan. There's also a mysterious third strain of modern goats, whose origins are still unclear. The idea was that the chickens would be infected by the virus if it crossed the U.S.-Canadian border, and scientists could quickly find the virus in their blood. But analysis of last year's programs in Canada and the United States showed the sentinel chickens didn't work as early indicators. This year, the chickens have been given the boot and instead, health officials will watch for the appearance of dead wild birds, and analyze their bodies for the presence of the virus.
Wild birds are highly susceptible to the virus, which can then be spread to humans by mosquitoes.
Nearly 100 people have been infected in the United States, but the virus has yet to appear in Canada. British researchers have come up with a plausible answer for the basic structure of five digits, one that's remarkably conserved in nature, in everything from bats to humans. The researchers looked at polydactyl mice, mutants with more than five digits on their paws. They found the extra digits changed the way other mouse bones formed. To accommodate the extra fingers, the bones in the mouse's paw had to form in an arc, rather than a straight line, which made it harder for the animal to run or walk.