The Riddle of Einstein's Brain

Nature and nurture

Is genius something you are born with or can you acquire it during childhood and education? In his 1869 book Hereditary Genius, Francis Galton, an ardent determinist if ever there was one, made a compelling case that exceptional ability had a tendency to run in families. Galton was convinced that this tendency was caused by a shared heredity, but with the biographical data that was available to him, he was unable to rule out the effect of a shared environment.

Today, there seems little doubt that genes are a force in the development of exceptional ability. Current estimates suggest that the heritable component of IQ scores ranges from 50 to 80%. But the brain of a new-born baby displays a remarkable plasticity, requiring constant environmental stimulation for it to blossom. In fact we now know that learning and experience have a direct impact on the development of the brain's neuronal architecture. In a sense, the brain is like a muscle that only gets bigger with exercise. Neglect it and it will wither.

During his lifetime, Einstein was keen to highlight what he believed were his own environmental influences. His special talent for thinking outside the box owed much, he claimed, to his fondness and familiarity with David Hume's A Treatise on Human Nature, a book that vividly exposed the limitations of human experience. Consequently, Einstein's special theory of relativity came to him suddenly 'with the thought that our concepts and laws of space and time can only claim validity insofar as they stand in a clear relation to our experiences; and that experience could very well lead to alteration of these concepts and laws,' he once explained.

Picking Einstein's brains

Over the last 20 years, several independent studies have purported to show a trace of genius in the pickled remains of Einstein's brain.

In 1985, a team of scientists led by Marian Diamond from Berkeley University in the US looked at the ratio of two types of brain cell – neurons and glial cells. While it is neurons that actually carry the brain 'waves', glial cells are no less important and are present in much greater numbers. These anonymous cells are the unsung heroes of the brain, providing structure, nourishment and a whole host of other benefits to the more celebrated neurons.

Previous research in rats had suggested that the support network of glial cells expands in response to mental stimulation. In other words, a larger ratio of glial cells could be interpreted as evidence of a more active, dynamic brain. The Berkeley team looked at four areas of the brain known to be associated with planning behaviour, spatial reasoning and language. They did indeed find higher percentages of glial cells in Einstein's brain compared to the brains of control subjects, although the differences were statistically significant in only one of the sections – the parietal lobe of the left cerebral hemisphere.

Einstein's parietal lobes hit the headlines again in 1999 when a study carried out at McMaster University in Canada uncovered some striking finds. Differences between Einstein's brain and ordinary mortals were most marked in the lower part of the parietal lobe – a region known to be associated with mathematical ideas and visuo-spatial abilities. Two features stood out. First, a fissure that normally divides this region was completely absent from Einstein's brain. And second, the region was unusually large.

Do these physical differences hint at a more extensive and integrated neuronal circuitry in Einstein's brain? And did the expansion of this area occur at the expense of neighbouring regions of the brain normally reserved for language? He was certainly a late developer when it came to speech.

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