Citations
By Carrie Golus, AB’91, AM’93
Image from iStockphoto
A song in their heads
Young finches practice songs in their sleep.
Young birds learn to sing by replaying adult songs as they sleep, wrote biologist Daniel Margoliash and psychology researcher Sylvan Shank, PhD’08, writing in the December 15 Nature. Implanting tiny electrodes into juvenile zebra finches’ brains, the researchers recorded nighttime spikes in neural activity that matched songs the young birds had spent the day hearing and rehearsing. Those spikes reorganized the birds’ neural networks, and the next day their singing improved. The researchers also found that the finches did not learn unless they could hear themselves sing. The study might help illuminate the role sleep plays in human learning.
Einstein may have been right (again)
Albert Einstein considered his cosmological constant—a factor he added to the theory of general relativity—to be his greatest blunder. But perhaps he was wrong about being wrong. A decade ago, scientists studying exploding stars discovered that the universe’s expansion seemed to be speeding up rather than slowing down after the big bang. Cosmologists, including Andrey Kravtsov, have seconded the conclusion that the universe is getting bigger faster by looking at the evolution of galaxy clusters. The findings, to be published in the February 10 Astrophysical Journal, strengthen the evidence that “dark energy”—the invisible force thought to be causing the acceleration—could be Einstein’s cosmological constant.
Stem-cell defense
Leukemia multiplies in part by taking over privileged “niches” within bone marrow where normal stem cells are supposed to divide and mature. As these microenvironments become malignant, the disease releases a chemical signal called stem cell factor (SCF), reported hematologist and oncologist Dorothy Sipkins in the December 19 Science, that draws stem cells away from tumor-free marrow sites and into the captive niches. There they lose the ability to make healthy blood cells and stop responding to drugs meant to coax them into the bloodstream where they can be harvested for transplantation. Sipkins discovered that in mice, blocking SCF helps protect stem cells; their numbers rise, and they regain the ability to migrate out of the bone marrow.
Acid bath
For years scientists have warned that as atmospheric carbon dioxide increased, so would oceanic acidity. But they had little empirical evidence to back up their predictions. Now they do. According to a study by ecologists J. Timothy Wootton and Catherine Pfister, the ocean is acidifying ten times faster than expected. Published in the December 2 Proceedings of the National Academy of Sciences, the study relies on more than 24,000 measurements of ocean pH over eight years—the first detailed data set at a temperate latitude, home to the world’s most productive fisheries. Potentially dire for sea animals with shells and skeletons that dissolve in acid, the corrosive environment could also damage the ocean’s ability to absorb carbon dioxide.
Two eyes for an eye
In everyday interactions, meanness can be more effective than civility, according to psychologist Boaz Keysar and Chicago Booth researcher Nicholas Epley. They published a study in the December Psychological Science that reports on a “dictator game,” in which one player had the power to decide how to split a sum of money. Participants in a “giving” game tended to reciprocate in equal measure, while those in a “taking” game reciprocated more harshly. The researchers found that subjects became greedier over repeated exchanges, perhaps explaining why conflicts escalate easily while generosity sputters out.