British researchers say crows show a skill most mechanics would envy: They can learn to use tools without being taught.

Zoologists at the University of Oxford say four New Caledonian crows raised in captivity developed the ability to retrieve meat from a crevice using a twig as a tool. The study was published this week in Nature.


Two of the crows were housed together and given regular demonstrations by keepers on how to retrieve food using twigs. Two others were housed individually and never witnessed demonstrations, said Ben Kenward, a zoologist in the school's department of zoology.

"I basically was a parent to them. When I went into the cages they watched me very closely," said Kenward, who raised the crows and performed the demonstrations.


Demonstrating twig use made no difference. All the crows figured out how to use the twigs when they were between 60 and 79 days old.

The crows, found in the South Pacific, use twigs and leaves in the wild to reach insects buried underground and in trees.

Kenward said the captive birds also attacked leaves, cutting them into shapes. But he said only one crow used leaf pieces to retrieve food. He expects the others to eventually develop the skill.

Gavin Hunt, a psychologist at the University of Auckland in New Zealand who also studies New Caledonian crows, said the study shows the birds may be genetically predisposed to using twigs.

"It's no surprise they use tools," he said. "They're like humans, they use tools every day."

The research is aimed at helping biologists understand differences between instinctive and learned behavior, Kenward said. "If you think about the evolution of human behavior and the evolution of culture, there's this unresolved issue involving how much of what we do is instinctive, versus how much is learned," he said.

-- Dennis O'Brien

Quick Takes


Better dining for cancer patients

One Bite at a Time: Nourishing Recipes for People with Cancer, Survivors, and their Caregivers (Celestial Arts, $19.95).

This book is a gem, especially if you are in the difficult position of caring for a relative or friend who is ill.

Baltimore native Rebecca Katz, who now lives in the San Francisco Bay area, has drawn on her expertise as a cook, whole foods guru and caregiver to produce a wonderful cookbook for people with cancer. The book is beautiful with savory pictures of sweet potato soup and squash stuffed with rice and poached ginger salmon.

The book, written with the assistance of fellow Baltimorean Mat Edelson, does more than give recipes, though. It outlines nutritional needs of cancer patients as well as gives a step-by-step guide to revamping your pantry and setting up a volunteer group to help during treatment and recovery.

Bottom Line: Dealing with a life-threatening illness is stressful enough. There's no reason to suffer through bland, mushy food, too.


-- Mary Beth Regan

Did you know...

A cavity is a bacterial infection in the enamel of the tooth. The only way to clean out the infection is to drill it out and fill the hole with metal or some other equally hard material.

-- Dr. Sheldon Margulies, The Fascinating Body: How It Works

In Brief

Gecko's sticky toes clean themselves


Anything sticky easily gets dirty, whether it's duct tape or a Post-it note. And once it's dirty, it will never be sticky again.

But researchers have found that the toes of the Tokay gecko, some of the stickiest things known to science, can clean themselves.

Scientists at Lewis and Clark College in Portland, Ore., studied the self-cleaning toes by dipping geckos' feet into some artificial dirt made of tiny beads of silica. Then they watched as the geckos went through some simulated walking. The gecko's toes became clean in only several steps.

In a report appearing online in the Proceedings of the National Academy of Sciences, the researchers reported that the force of attraction between the dirt and the toes is less than the attraction between the dirt and the walking surface, resulting in a self-cleaning effect.

Overworked doctors as dangerous as drunks

Lack of sleep from very long hospital shifts can make young doctors behind the wheel as dangerous as drunks, researchers found.


Doctors in training were more than twice as likely to get in a car crash while driving home after working 24 hours or longer, compared with when they worked shorter shifts, according to a study by Harvard Medical School researchers. The study also found that after extended shifts, young doctors sometimes fell asleep while driving.

The study, reported in yesterday's New England Journal of Medicine, was done by some of the same Harvard Medical School researchers who just last fall reported that sleep-deprived doctors made one-third more medical errors during their many long shifts, compared with shorter shifts.

Mother rats prefer nursing over cocaine

Given a choice, female rats would rather nurse their young than take a hit of cocaine -- at least while the kids are young -- according to new research.

Scientists at the University of Massachusetts Medical School used functional magnetic resonance imaging to analyze brain responses in virgin and nursing mother rats. They found not only that nursing and administration of cocaine stimulate the same "reward circuit," but also that mother rats actually prefer nursing. Doctors theorize that this preference may preserve the integrity of the mother-child bond.

But the nursing "high" doesn't last long, according to the Report in the Journal of Neuroscience. After 10 days, the mother rats' brains responded pleasurably to cocaine once again.


-- From wire reports