If these association systems expanded beyond their extent in modern humans, they would likely enhance mental abilities even further, Lynch and Granger say. This was the case, they hypothesize, with a few hominids whose skulls were discovered in the South African Boskop region in the early 20th century. The find initially caused excitement because the skulls had large frontal bones, suggesting that they may have belonged to a separate species that had brains larger than those of humans. Lynch and Granger argue that these “Boskops” had fallen into obscurity by midcentury because they did not fit our preconceptions. The consensus among anthropologists, however, is that the skulls simply belonged to modern humans. But the picture the authors paint of a bigger-brained hominid is fascinating nonetheless.
The Frog Who Croaked Blue
by Jamie Ward. Routledge/Taylor & Francis, 2008 ($31.95)
Russian newspaper reporter Solomon Shereshevskii had gotten himself into trouble. It was the mid-1920s, and he had been assigned to cover an important speech in downtown Moscow but failed to take down a single word of it. His editor was not happy—until Shereshevskii recalled the entire speech word for word, a feat he could perform effortlessly because of the way his senses operated. Every time the reporter heard a word, it triggered certain images, flavors and smells in his mind. The speech was literally embedded in multisensory code.
Shereshevskii—whose memory later made him famous as a stage performer—had synesthesia, a condition in which one or more of the senses are inextricably linked. The variations are endless: music has color, words have flavor or numbers appear embedded in a three-dimensional map. People with synesthesia “experience the ordinary world in extraordinary ways,” writes author Jamie Ward of the University of Sussex, an expert on the condition, which is thought to affect as many as one in 25 people (many of whom do not realize their perception is unusual).
The Frog Who Croaked Blue reads like a fascinating novella-length essay. Ward is clearly enthralled by the topic, and he has no trouble finding interesting issues to address. He explores synesthesia’s potential causes (most people are born with it, but it can also be triggered by psychoactive drugs such as LSD), how and why the brain mixes the senses, and whether the condition might confer intellectual and even evolutionary benefits, such as a better memory. Between scientific discussions, he interweaves fascinating personal narratives from synesthetes around the world.
The most interesting part of the book, however, has little to do with synesthesia per se. Ward maintains that although smelling colors and hearing shapes may be exceptional, our senses are more closely intertwined than we probably realize. Certain neurons in the brain appear to be multisensory in that they can transmit auditory, visual and tactile information; when two types of stimuli are presented at the same time (when a circle appears on a computer screen at the same time that a beep sounds, for instance), these neurons respond more than twice as strongly to the combination than they do to either event alone.