Archive for April, 2007

Be Not Sad for the Shad

By Amos Zeeberg (Discover Web Editor) | April 26, 2007 1:07 pm

Salmon get tons of fame and admiration for their epic, sex-crazed journeys up mighty rivers during spawning season, but the unsung shad may be even more devoted to answering the underwater booty call: While salmon make their spawning runs only once in their lives, an individual shad can do it several times.

Shad recently began their spawning runs on the East Coast and, if a recent trend continues, there will be more than there were last year. Since the Clean Water Act’s passage, shad are returning to many rivers where they had been pushed out by pollution. The shad’s elated human fans are celebrating at various shad fests (really).

This nice radio story highlights the return of the shad to Philadelphia’s rivers, particularly. With Earth Day coming right up, it’s a heart-warming little tale of eco-success. Not everything’s doom and gloom!

Sampler from a New York Science Smorgasbord

By Amos Zeeberg (Discover Web Editor) | April 24, 2007 1:35 pm

On Friday, the New York Academy of Sciences rounded up four science all-stars at the Academy’s new downtown home and let them loose on some of the hottest topics in their respective fields. In case you missed it, here are the highlights:

1) Blame it on my genes

Columbia professor of psychiatry and law Paul Appelbaum tackled the messiness that results when law and genetics mix. Consider that some genes seem to show a correlation with aggressive behavior, particularly when they occur in combination with environmental factors (like child abuse) that might promote aggression. These findings, Appelbaum says, “have opened the eyes of people in law and criminology to the importance of behavioral genetics.” Specifically, some defense lawyers realized that genes might be a viable excuse. Think of the insanity defense: “Our legal system excuses people from culpability if they have an impaired ability to control their behavior,” Appelbaum explains.

So could testing positive for a genetic predisposition to violence protect defendants? At least for now, probably not. In a triple murder trial where this defense was attempted, the scientist testifying acknowledged that while the defendant’s genetic makeup was associated with aggression, in the end he still had a choice of whether or not to kill three people. But with more and more genetic information becoming available, Appelbaum now wonders whether genetic testing might be dropped as a defense and adopted as a rationale for harsher sentencing. After all, if violence is in your genes, you might not respond to remediation and could be more likely to strike again. Future criminals might want to think twice before pointing the finger at their DNA.

2) Evolving culture

Tufts philosopher Daniel Dennett took a broad look at the evolutionary innovations that allowed humans to develop culture, and how culture in turn can affect our evolution. How is it, he wondered, that humans went from a minor primate accounting from 0.1% of terrestrial vertebrate biomass 10,000 years ago to 98% of that total today (including our livestock)?

He argues that humans have benefited from what he calls “cranes”: evolutionary “speed-ups” that make evolution itself more efficient. While the physiological changes in our brains were important, he says that the real key to human dominance came from the division of labor made possible by the coevolution of language and culture. “Big brains are as much an effect as a cause of culture,” Dennett says. A lot of biologists focus on the transmission of genes, but the transmission of information is crucial, too: “Mother nature is not a gene-centrist. Biology isn’t all about genes.” He calls cultural transmission (which occurs most extensively in species with long, parented childhoods) “the second information highway.” When optimized, it’s possible for rogue cultural variants to start being transferred horizontally, from person to person (rather than vertically, from generation to generation). “Primate brains got invaded by ideas to die for,” which he says include religions, political and economic systems, justice, and freedom, among others. “Now that they had these infected brains, they could start thinking outside the box.”

While other species may have a form of culture, he says, we seem to be just about the only one whose members are often happy to dedicate their lives to culture rather than maximizing reproduction. “Probably the single most important factor in lowering human fertility is higher education,” says Dennett (only half jokingly). “Reproductive fitness is not what matters most to us. We’ve evolved other values that we care more about.”

3) Is national security sick?

Science journalist and Council on Foreign Relations senior fellow for global health Laurie Garrett explored the relationship between emerging diseases and national security, with an emphasis on how politics seem to trump preparedness when it comes to planning for an epidemic and dealing with the international ramifications. The risk of diseases like avian flu is transnational, yet the federal government puts the responsibility for dealing with disease outbreaks at the feet of states and individual communities. “Threat is globalized,” she says. “We’re all sharing a microbial world that was once distinctly separated. Now, an outbreak somewhere else can be here overnight.”

Garrett points to avian flu as a threat with implications not only for public health but for foreign policy. “Rich countries would have any tools there were to deal with an outbreak. They would deny them to the rest of the world and deal with the foreign policy fallout afterward.” Such tensions are already coming into play: in 2006, Indonesia decided to stop sharing strains of the virus with other countries for research, a collaboration crucial for tracking the flu’s evolution. “They government had just had enough,” said Garrett. “They realized, ‘You guys are going to go off and make vaccines and treatments against these viruses. But where’s the benefit for us? Where are the vaccines and the Tamiflus for the poor people here?’ ”

China’s response to SARS provided a chilling example of what happens when a nation is caught off guard by an outbreak: communities cordoned themselves off from one another, cities were locked down, and travel was restricted by mandatory fever checkpoints and detention of symptomatic individuals. “Think about America,” Garrett implored. “How would we be different? What is different about our capacity to respond to a pandemic?”

4) About those extra dimensions…

Columbia string theorist Brian Greene discussed the story behind how we found ourselves confronted with “the stunning possibility that our world has more than the three dimensions of space that we see around us,” when our everyday observations make it so obvious that up-down, left-right, and back-forth are all we’ve got. Unfortunately for our wimpy human minds, 3D just doesn’t cut it in the mathematics of string theory, the controversial field attempting to forge a union between the otherwise-incompatible physics of the itty-bitty (quantum mechanics) and the rest of the universe (general relativity).

Greene says, “We believe this theory is capable of uniting these laws for the first time in the history of physics, and it requires more dimensions. The math fell apart if the world has only three, but at ten dimensions of space, all the math problems go away.” Theorists have suggested that the extra dimensions may be curled up too small to be detectable in normal experience. “These tiny dimensions may hold the answers to some of the deepest questions physicists have pondered for a long time,” he explains, like the fundamental parameters (the mass and charge of the electron, the strength of gravity, etc.) that seem to be just right for making the universe work.

Exactly what is this string theory business, you might ask? DISCOVER readers competed to explain just that in a video contest last month. Check back soon to see the winner selected by Brian Greene, but in the meanwhile, you can learn more here.

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