Research
Citations

---

He smells, she smells
Women apparently prefer the odor of men who are genetically similar to themselves, according to research reported by postdoctoral fellow Suma Jacob, AB'91, PhD'98, MD'01; Martha K. McClintock, the David Lee Shillinglaw distinguished service professor in psychology; and human-genetics professor Carole Ober in the February Nature Genetics. The study, which had women sniff T-shirts that men had worn for two days, found that a woman's preference is based on the man's genetic match to her paternal genes. The researchers believe the gene-matching system's evolutionary purpose is to avert the risks of both inbreeding and outbreeding: while mating with a close relative increases the risk of a child with bad versions of the same genes, mating with someone too different, says McClintock, "leads to the loss of desirable gene combinations."

The feeling lasts and lasts
Researchers have long known that nicotine stimulates pleasure by causing the brain's "reward center" to release dopamine. But now Daniel S. McGehee, assistant professor of anesthesiology & critical care, has shown it also neutralizes the dopamine "off-switch," so the feel-good chemical just keeps on coming, according to a study in the March 14 Neuron. No wonder, he says, the stuff is so addictive.

When diversity's a bad thing
Investors beware: conglomerates-highly diversified corporations-are less than the sum of their parts when it comes to the value of their assets. Thus, proposed mergers should be viewed with skepticism. This is according to associate professor of finance Owen Lamont in the January Journal of Financial Economics. Lamont compared the asset values of firms that merge with those that spin apart to show that "diversification destroys value."

Dissecting anthrax
Chicago researchers have worked out the three-dimensional structure of the edema factor, part of the deadly toxin produced by the anthrax bacteria. The edema factor, so called because it causes swelling, changes shape when it bumps into a common cell protein called calmodulin, report Wei-Jen Tang, associate professor in neurobiology, pharmacology, and physiology, and doctoral student Chester L. Drum, AM'94, in the January 24 Nature. The change causes the toxin to generate a chemical messenger that blocks the body's cells from alerting the immune system of a bacterial invasion.

Take it out of your next raise
Procrastination is a major reason Americans don't save for retirement ("Investigations," December/01). So why not get employees to agree in advance to devote future pay increases to savings? That's the thinking behind "Save More Tomorrow," a plan presented by Richard Thaler, the Robert P. Gwinn professor of behavioral science and economics, at the January meeting of the American Economics Association. In a test program at a Midwestern firm, Thaler says savings rates for participating employees jumped from less than 4 percent to nearly 12 percent in 28 months. He is working with the Vanguard Group, which administers 401(k) programs, to run a pilot program at Philips Electronics.

Other dimensions in sight?
At the February convention of the American Association for the Advancement of Science, Maria Spiropulu, an Enrico Fermi Fellow, said she expects to discover so-called space warps-hidden dimensions besides space and time-by 2005. Spiropulu recently led the analysis of data from experiments at Fermilab's high-energy particle accelerator. In those collisions, the conservation of energy and momentum can be measured, so what's left over after a crash-and most importantly, what's not there-may be the telltale clue. "A significant imbalance would indicate the graviton [the particle that carries gravity] has trickled into an extra dimension, a place where gravity may become very strong and other weird properties may kick in," Spiropulu says. There's no hard evidence of the dimension yet, but she believes it's just around the corner.
- S.A.S.

---