Outside her office in Boston this week, Carin Willis was wearing her MBTs, which have big, thick, curved soles that look like big rubber rockers. "They're very heavy.

"There are some cues that can only be conveyed by a woman's body, like her pregnancy status," says Jaime Confer, who coauthored the study with graduate student Carin Perilloux and Prof. David Buss.

Carin says this future enclosure will be greatly improved in terms of environmental, behavioral and social enrichment for the lovely otter.