How Does the 

 Greenhouse Grow? 



"Everyone knows" that plants are helping 

 to put the brakes on global warming by ab- 

 sorbing greenhouse gases. But two new 

 studies show that the plant kingdom won't 

 brake the warming trend quite as hard as 

 everyone has assumed. 



Astonishingly, plants may produce as 

 much as a third of the methane, an important 

 greenhouse gas, that is released into the at- 

 mosphere each year. An international team 

 led by Frank Keppler, a geochemist at the 

 Max Planck Institute for Nuclear Physics in 

 Germany, placed plants and leaves in sepa- 

 rate sealed chambers containing methane- 

 free air. After a set time they analyzed the air, 

 and discovered that both living plants and 

 dead leaves make methane, though living 

 plants make much more. What's more, both 

 living and dead vegetation do it aerobically, 

 contradicting the generally accepted view 

 that when methane is produced biologically, 

 oxygen must be absent. Both how plants 



Ain't No Ocean 

 Wide Enough 



In October 1988, ships off the coast of 

 Africa reported massive swarms of desert 

 locusts {Schistocerca gregaria) flying west 

 over the Atlantic. A few days later some of 

 the insects turned up on Caribbean islands, 

 exhausted but alive. That 1988 exploit may 

 have been a rare repeat performance of a 

 momentous event, according to Nathan R. 

 Lovejoy, a zoologist at the University of 

 Toronto, and several U.S. colleagues. After 

 analyzing Schistocerca DNA, the team con- 

 cluded that an ancestral locust from Africa 



make methane and how science previously 

 failed to detect the process remain mysteries. 



Another international team, led by Andrei 

 Lapenis, a climatologist at the University at 

 Albany in New York, investigated a puzzling 



Immigration Reform 



Who were the New World's first inhabitants? 

 The ancestors of present-day Native Ameri- 

 cans are thought to have come from north- 

 ern Asia, but new research bolsters the theo- 

 ry that another group arrived first. 



Walter A. Neves and Mark Hubbe, anthro- 

 pologists at the University of Sao Paulo in 

 Brazil, examined eighty-one skulls that were 

 unearthed from the Lagoa Santa region of 

 central Brazil. The skulls — all between 7,500 

 and 1 1 ,000 years old — belonged to members 

 of the group thought to have been the first 

 Americans. The anthropologists compared the 

 skulls' dimensions with 

 a database of 

 skulls from 



Simocyon batalleri, an 

 ancestor of the red panda 



five continents. Their finding: the skulls of an- 

 cient Americans most closely resemble those 

 of present-day Australians and Melanesians. 



Intriguingly, people with similar skulls are 

 known to have lived in east Asia 20,000 years 

 ago. Sometime earlier, ancestors of this 

 group had likely split off to colonize Australia 

 and Melanesia. The anthropologists theorize 

 that members of the east Asian contingent 

 migrated to the New World via the Bering 

 Strait some 15,000 years ago. North Asians, 

 forbears of modern aboriginal Americans, 

 likely followed soon after. The fate of the 

 Americas' first colonists is still unknown. 

 [PNAS 102:18309-14, 2005) 



— S/on E. Rogers 



Thumbs Up 



Only two panda species survive, but thanks 

 to the late Stephen Jay Gould, their 

 "thumbs" are immortal. For Gould, the pan- 

 da's curious extra digit illustrated how natural 

 selection solves problems by refashioning 

 new body parts out of old ones. The panda's 

 "false" thumb is formed from a highly modi- 

 fied wrist bone; it's handy for holding the 



Solitary (left) and swarming (right) forms of 

 African desert locust 



gave rise to not only the African desert lo- 

 cust, but also to the fifty-odd Schistocerca 

 species of the Americas, which includes 

 grasshoppers, as well as locusts. The DNA 

 points to a single colonization between 

 three and five million years ago. 



The superinsects that made the epic 

 crossing probably got help from thermal 

 updrafts. Once lofted to 6,000 feet, strong 

 westward winds could have rushed them 

 along to their new home. [Proceedings of 

 the Royal Society B, in press) 



— Stephan Reebs 



discrepancy in Russia's boreal forest. Satellite 

 images indicated a dramatic proliferation of 

 greenery in recent decades, which climatolo- 

 gists have taken to mean the trees were ab- 

 sorbing extra carbon dioxide in response to 

 warmer, wetter weather. On-the-ground sur- 

 veys, however, showed a much smaller 

 growth spurt. 



After examining fifty years of forestry 

 records, Lapenis and his colleagues concluded 

 that the Russian trees had made a surprising 

 shift. They were producing much more foliage 

 than before, but only a little more wood. Trees 

 store carbon much longer in branches and 

 trunks than in relatively disposable leaves and 

 needles. As a result, Lapenis expects that 

 though trees will absorb more carbon as the 

 climate changes, the increase will be only a 

 third as large as expected. 



It seems that the more we need trees to 

 clean up after us, the less obliging they turn 

 out to be. (Nature 439:187-91, 2006; Global 

 Change Biology 1 1 :2090-102, 2005) 



— Samantha Harvey 



panda's favorite food, bamboo. In fact, the 

 panda's dietary fondness for bamboo has 

 long been held as the driving force behind 

 the evolution of the thumb in both the red 

 and the giant panda. 



But Manuel J. Salesa, a paleobiologist at 

 the National Natural History Museum in 

 Madrid, and his colleagues have found a fore- 

 runner, at least in the red panda's case. An ex- 

 tinct relative of the red panda, Simocyon 



NATURAL HISTORY March 2006 



