MARCH 2006 



VOLUME 115 



NUMBER 2 



FEATURES 



COVER STORY 



32 LEARNING TO 

 FIND YOUR WAY 



The biochemical pathways 

 underlying spatial memory 

 in the brain are giving up 

 their secrets. 

 ERIC R. KANDEL 



54 OUR ANTHROPOID ROOTS 



Those curious primates from Pondaung, 

 and other leads in the quest 

 for an early ancestor 



RUSSELL L. CIOCHON AND 

 GREGG F. GUNNELL 



48 SMART WEAPONS 



With an arsenal of quills and chemicals, 

 the porcupine mounts one of nature's most 

 robust defenses against predators. 



ULDIS ROZE 



ON THE COVER: Benjamin Edwards, 

 Immersion, 2004 



