Findings

In the last 30 years, only the bald eagle and a handful of other species have recovered enough to be taken off the federal government's list of threatened and endangered species. Others, like the California condor (left), require constant help from humans to survive the threats they face. In fact, the vast majority of these species are "conservation reliant," said John Wiens of the Point Reyes Bird Observatory, based in Petaluma, California, this morning. And they may never be taken off the list.

Wiens and Michael Scott of the U.S. Geological Survey in Idaho wanted to know how many of the 1954 listed species will require constant conservation to endure. They examined recovery plans issued for the species and gauged the likelihood that species could be delisted. About 80% of the species are conservation reliant and will remain on the list, they found. "We thought it would be lower," Wiens said. "We were quite astounded."

The situation is likely to get worse. Because habitat destruction and other threats are increasing, more species will probably need to be listed--adding to costs of keeping species on life support. "It may be unrealistic to think that we can maintain a growing balance sheet of conservation-reliant species," Wiens said. That means more thinking will be needed about how to prioritize funds spent on endangered species.

--Erik Stokstad

Hang out with people who study human diet long enough, and eventually you'll be asked to lick a strip of paper. That's what happened to me on Friday, when I joined the speakers from The Evolution of Human Diets session for lunch after their seminar. Anne Stone of Arizona State University handed me a strip from a vial, as if she were handing out toothpicks after a meal. When I licked it, I tasted only a mild acrid flavor, like licking the glue on an envelope. I was a "nontaster," she said. Not so for the co-organizer of the session, paleoanthropologist Peter Ungar of the University of Arkansas. He told me that when he licked the paper, it was intensely bitter--he grimaced to show me just how awful. He was definitely a "taster."

It seems that we all were licking paper dipped in phenylthiocarbamide, or PTC, which is a bitter organic compound. PTC does not occur in food, but people who can taste PTC are supersensitive to bitter compounds in foods such as broccoli and Brussels sprouts. Stone brought the PTC to Chicago to show how humans vary in their ability to taste different foods.

Where did this sensitivity come from?
 

Kissing helps men and women choose life's greatest prize. What is it? Find out in this Valentine's Day podcast from Science podcaster Robert Frederick. For more on why we kiss, check out a related blog item posted earlier today.

Compounds derived from a marine sponge can thwart the defenses of a broad range of antibiotic-resistant bacteria, a researcher reported here yesterday. The chemicals, which are nontoxic, somehow break down tough agglomerations of bacteria, called biofilms, which leaves the bacteria vulnerable to conventional antibiotics.

Several kinds of compounds can help disrupt biofilms, but none have reached the clinic. The new compounds were derived over the past several years from a molecule called ageliferin by Christian Melander of North Carolina State University (NCSU) in Raleigh. These compounds break down biofilms and prevent their reformation "with unprecedented effectiveness," according to NSCU colleague John Cavanagh's Web site. They are "extremely broad-acting," he told Science.

The news on climate change seemed bad enough in 2007, when the Intergovernmental Panel on Climate Change (IPCC) announced in their fourth assessment report that "warming of the climate system is unequivocal," that humans were "very likely" to blame, and that if we keep pumping greenhouse gases into the atmosphere, climate will "very likely" change much more than it did in the 20th century. But researchers reported today that, in the 2 years since the report was released, the news has gotten even worse.

Climate scientist Chris Field of Stanford University relayed the first bit of bad news to a sober audience during his talk, "What is New and Surprising since the IPCC Fourth Assessment." According to a paper his group published in the Proceedings of the National Academy of Sciences in 2007, humans are now pumping out climate-warming gases nearly three times faster than the IPCC authors anticipated in their worst-case scenario. Specifically, Field described how carbon emissions had been increasing at 0.9% per year through the 1990s, but accelerated to 3.5% per year growth between 2000 and 2007.

Why the disparity?

Just when gas prices have finally fallen, here's another reason to cringe at the pump. The ethanol produced on millions of new hectares of corn in the United States in the last 2 years--touted as the green future of oil and gas--will increase deforestation in the Amazon and result in a large increase in carbon emissions to the atmosphere. That's the conclusion from research presented at a symposium this afternoon on biofuels and tropical deforestation. In fact, most new farmland in the tropics is converted from forests that had been rich storehouses of carbon, another scientist reported.

What aspect of how we eat is universal across all human cultures?  And why does Northwestern University anthropologist William Leonard say that we are victims of our own evolutionary success?  Find out in this podcast from Science podcast host Robert Frederick. 

Origami is known to most as the art of fancy napkin-folding and turning paper into cranes. But for scientists, origami is a mathematical tool, useful for everything from medical implants and architecture to molecular modeling. The panelists from today's session on "The Mathematics of Origami" sat down for a lunch with me to take stock of their field.

The discussion was led by MIT mathematician Erik Demaine, who helped prove mathematically in the 1990s that a piece of paper can be folded into any shape. Before that, it was thought impossible to, say, create a grasshopper with all its legs and antennae. "Now the big question is not whether something can be folded," he says, "but can it be folded nicely?" For example, minimizing the number of creases becomes important when trying to fold a rigid material such as metal.

So what about that bunny rabbit?

Things are heating up here at the AAAS meeting. For Valentine's Day, scientists explored the evolutionary importance of the kiss. Almost all cultures seek out its spine-tingling sensation, but exactly why we do is a matter of debate. In some preliminary work, researchers reported what could be a valuable insight for kissers around the world: Disney may be the anti-aphrodisiac.

Scientists still don't know why kissing might have evolved or whether its roots are primarily cultural or biological. There are analogous behaviors in the rest of the animal world: Foxes lick one another, for example, birds tap their beaks, and primates have been known to kiss. As for humans, some researchers think that kissing could harken back to nursing or premastication, when a mother chews food for her children and transfers it into their mouths. The oral and neural stimulation of kissing might reignite subconscious feelings of early attachment.

With dozens of high-powered human evolution specialists roaming the AAAS meeting, it's only natural that the hallway buzz focused on the rough draft Neandertal genome sequence announced Thursday. But might that DNA actually have come from a modern human bone? That controversial possibility was raised by Milford Wolpoff of the University of Michigan, Ann Arbor, one of the most vocal proponents of the notion that Neandertals and modern humans shared genes.

The bone, sequenced by Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was found in Vindija Cave in Croatia, a well-known Neandertal site. But the little chunk of bone that yielded DNA is so incomplete that anatomists can't say whether it's from a Neandertal or a modern human. And at 38,000 years old, it could have been either, said Wolpoff. The bone is "young enough for a late Neandertal or a modern human, or a mix," he said.