SCIENCE

Notebook

Planning Not Unique to Humans

Human beings aren't the only creatures capable of planning ahead, according to two new animal studies published last week in the journal Science. One experiment on two types of apes -- bonobos and orangutans -- suggests that the skills for planning arose 14 million years ago, while a separate experiment on Western scrub jays shows that they remember which individual bird watched them as they hid food, and adjust their hiding behavior accordingly.

Two researchers at Germany's Max Planck Institute for Evolutionary Anthropology, Nicholas J. Mulcahy and Josep Call, ran tests on apes in which they chose, transported and saved appropriate tools for tasks they performed either one hour or even 14 hours later.

In a separate experiment, three Cambridge University researchers -- Joanna M. Dally, Nathan J. Emery and Nicola S. Clayton -- observed scrub jays hiding food caches for future consumption, stealing the food of their rivals and taking steps to protect their own stores from such thievery. The scrub jays would recover their caches and hide them again when they observed another bird watching, even if the rival in question did not have a chance to steal from them.

In their paper, Mulcahy and Call wrote: "Together with recent evidence from scrub jays, our results suggest that future planning is not a uniquely human ability, thus contradicting the notion that it emerged in hominids only within the past 2.5 to 1.6 million years." Instead, they suggest that the planning skills "evolved in great apes before 14 million years ago, when all extant great ape species shared a common ancestor."

-- Juliet Eilperin

Insight Into Heart's Development

Embryonic hearts suck!

That's the bumper-sticker summary of new research that overturns the standard paradigm for how the heart circulates blood during early development, when it lacks chambers and valves and is essentially just a pulsing tube.

The going theory has been that this tube squeezes blood along with a rhythmic, peristaltic motion like the one that pushes food through the intestines. But Morteza Gharib and Arian S. Forouhar of the California Institute of Technology had reason to suspect otherwise.

Using new microscopic techniques to watch the embryonic heart in action inside developing zebra fish (which are conveniently transparent), the two scientists and their colleagues noticed that blood cells were moving along faster than the motion of the pulsing tube-heart. They also noted that the tube was squeezing and then opening only at the intake end and not all along its length, as happens with peristalsis.

Further analysis has now led the team to offer an alternative explanation: The periodic squeezing of the tube at its intake creates a tiny wave of blood that runs through the tube's length, like the wave caused by pushing one's hand forward in a pool. When that wave gets to the tube's far end, it bounces back, as it would upon hitting the pool's wall.

As long as the pulsing occurs at the right speed, the team found, those bouncing waves reinforce each other in a way that stretches and widens the tube at the far end. That creates a low pressure area -- and suction -- which pulls, rather than pushes, blood through the heart, the team reported in the May 5 issue of the journal Science.

The team hopes to use its insight to design circulatory "boosters" to help people with weak hearts.

-- Rick Weiss

Brain and Machinery of Prejudice

When people think about someone they believe is politically or socially similar to them, a particular region of the brain becomes active. But when they think about someone they see as significantly different, another part of the brain lights up, new research indicates.

Using magnetic resonance imaging, researchers at Harvard University and the University of Aberdeen in Scotland identified two regions of the brain's medial prefrontal cortex that were stimulated differently by questions designed to reveal how similar, or dissimilar, another person might be.

The study subjects were asked, for instance, to think about a typical, liberal student at a Northeastern college and about a fundamentalist Christian. The subjects were then asked questions about these imagined people, such as whether they would look forward to going home for Thanksgiving, enjoy having a roommate from another country, or would like European movies better than Hollywood movies.

The brain imaging found that Boston area college students consistently activated different parts of their brains depending on which person they were thinking about. Thoughts about people they considered similar were focused in the frontal part of the brain region, and thoughts about people they considered different triggered activity in the rear.

The authors theorized in the May 18 issue of the journal Neuron that the divergent brain activity may provide insight into the machinery of prejudice: "To the extent that members of a social group other than one's own are viewed as dissimilar from oneself, the current results suggest that perceivers may actively deploy a different set of social-cognitive processes."

-- Marc Kaufman