Science Roundup

this week in mammalia

by by Nick Werle

illustration by by Laura Armstrong

This week, scientists learned who among them will enter the Swedish Pantheon of Nobel science. But just because the lucky few are partying in Stockholm doesn’t mean that the rest of science is stopping to watch. Find out what discoveries are delighting nerds everywhere.

Koalas under siege
Australia’s koalas are stressed out, and it’s killing them at an astounding rate, according to the Australian Koala Foundation. Since the arrival of Europeans in the 1700s, human development has destroyed about 80 percent of the continent’s eucalyptus forests. Koalas are picky and rely exclusively on the trees for their food, water, and shelter. As humans encroach on their territories, koalas are forced into ever shrinking, isolated stands of eucalyptus. Not only does this displacement destroy these gregarious marsupials’ social lives, but it also exposes them to suburban perils: cars, dogs, and swimming pools. 

Just as the onset of midterms helps mononucleosis spread through the halls of Archibald and Bronson, koalas’ high stress levels make them more susceptible to a variety of deadly diseases. Chlamydia has been particularly devastating, since environmental stressors magnify the lethality of the disease, which normally infects 50 – 90 percent of the koala population. A 2008 count of Queensland’s Koala Coast’s furry residents indicated that the koala population has fallen 64 percent from about 6,200 in 1999 to 2,800 last year. Researchers estimate that 60 percent of these deaths were due to Chlamydia. Current work estimates that there are 100,000 koalas in Australia today, down from several million before European settlement.

The issue of Australian marsupials’ declining fortunes came to prominence recently when a national celebrity, Sam the Koala, died during surgery to address her Chlamydia-scarred organs, according to the Associated Press. When Chlamydiosis, the viral cause of the disease, becomes active in over-stressed koalas, they experience an array of painful infections in the eyes, urinary, reproductive, and respiratory tracts. These infections can result in blindness, infertility, and death in addition to a condition known by the Koala Foundation as either “wet bottom” or “dirty tail.”

Lucy, meet Ardi
There’s a new older woman who has the whole world abuzz with paleoanthropological excitement. Ardi, who at 4.4 million years old is the earliest fossilized hominid ever discovered, was introduced to the world this week in a special issue of the journal Science, which included 11 papers describing the anatomy, environment, and evolutionary significance of Ardipithecus ramidus.

While this potential "missing link" with chimpanzees was first announced 15 years ago, researchers have been continuously excavating at the dig site near the Awash River in the Afar Rift region of Ethiopia. Paleontologists have identified remains from 36 different individuals including Ardi, who, with more than 110 recovered pieces, is the most complete specimen.

Ardi’s discovery is exciting because it includes many important parts of her body, including not only most of her skull and teeth but also her pelvis, hands, and feet. Analysis indicates that Ardi was an omnivorous, forest-dwelling, “facultative biped,” who split her time between walking upright on the ground and climbing efficiently on all fours up in the trees. Researchers estimate that she stood about 47 inches tall and weighed close to 110 pounds.

Lucy, the 3.2-million-year-old skeleton currently on display at the Discovery Times Square Exposition in New York, clearly has the most to lose now that there is a new oldest hominid. Genetic analysis suggests that chimpanzees and humans share a common ancestor that lived about 6 million years ago, and while Ardi lived millions of years after this theorized split, she represents a great leap back in time from Lucy. Her skeleton, which brings science closer than ever to this missing link, challenges some previous assumptions about the evolution of Lucy’s savannah-dwelling hominids from woodland primates that walked on their knuckles across the forest floor.