Science: Update

FILAMENT-LIKE structures discovered deep beneath the western Australian seabed could be the smallest living organisms, according to their discoverers. The "nanobes" are between 20 and 150 nanometres in diameter (a nanometre is a billionth of a metre), tinier even than the smallest known bacteria, Mycoplasma, which have no cell walls and measure from 150 to 200 nanometres in size.

The objects were discovered by Phillipa Uwins and a team of geologists from the University of Queensland in Brisbane. The nanobes' habitat is a sandstone core where the temperature is above 150 Centigrade, but in the laboratory Uwins found that they appeared to have DNA.

Others have questioned the finding, suggesting that the DNA could be contamination. But if nanobes really are alive, it could give some impetus to the flagging claims that the traces found in the Martian meteorite ALH840011 are fossilised nanobacteria. The objects there were only 20 nanometres across, which has led many biologists to dismiss the suggestion that they came from living things.

CHINESE RESEARCHERS have found the earliest known complete skeleton of a mammal - a mouse-sized, insect-eating creature about 10 centimetres (4 inches) long. It belonged to a group of primitive animals called triconodont, and lived about 145 million years ago.

The bones, which were discovered in 1997 at a famous dinosaur site in northeastern China, mark the first time the complete skeleton of an early mammal has been discovered, and should offer important insights into their evolution. Until now, scientists have had to piece together the early history of mammals from fragments of isolated teeth and bones.

CAN IT really be true? Eating chocolate may reduce the chance of heart disease by helping arteries remain unclogged, according to a study from the University of California, Davis. It found that cocoa contains chemicals called flavonoids - these work as antioxidants to prevent fatty deposits sticking to artery walls. The study was sponsored by Mars, makers of the eponymous bar, but the findings were credible, being presented at the American Chemical Society's national meeting in Anaheim, California.