It is against this background that we must assess the continuing progress in brain sciences. Neuroscience is steadily gaining a deeper understanding of how the brain of Homo sapiens enables the functioning of the mind—with its intellect, will power, emotions, and mysterious consciousness. This understanding is helped along by new, noninvasive technologies that permit researchers to observe mental functions within the living brain. The new diagnostic tools include Functional Magnetic Resonance Imaging, Transcranial Magnetic Stimulation, and Positron Emission Tomography. They are already providing valuable data on what goes on inside the brain when it is engaged in specific mental activities. More recently, scientists have successfully used nano-sensors and fluorescent imaging to observe changes in the chemistry of individual brain-cells.9
Might this new knowledge point the way to enhanced human intelligence? Numerous research projects have succeeded in improving the mental faculties of animals via genetic engineering. By targeting a single gene, experiments with mice have shown measurable improvements in memory. Other experiments explored molecular processes affecting the plasticity of certain neural functions, which might show a way to limit, or reverse, age-based declines in learning. But human intelligence appears to be a polygenic trait (i.e., governed by multiple genes), and efforts to raise it substantially via genetic engineering might be difficult.10
Distinguished scientists have mentioned another possibility: An increase in brain size could be the catalyst to bring about decisive gains in intelligence. Among different species, and within our own species, intelligence is correlated with brain size. The brain of a chimpanzee, one of the closest precursors of Homo sapiens, is less than one-third the size of the human brain. During the evolution from man’s primate precursors to Homo sapiens, some change in the genetic endowment governing brain size must have created the larger brain that now accommodates the human mind. What if it turned out that one or a few genes constituted the key to a further enlargement of the human brain, which might in turn lead to a higher level of human intelligence? This tantalizing possibility has gained support from genetic research into the cause of microcephaly (a shrunken braincase).11
The desire to enhance the faculties of the human mind is of course nothing new. Since antiquity, two complementary approaches have been pursued. One works directly inside the human brain, using memory drills, problem-solving practices, as well as chemical interventions, say, with caffeine or Ritalin. The other approach assists the mind from outside the body, via the senses of sight, hearing, or touch. This external approach has employed written text and ever more powerful computational aides from the abacus to the latest computers. But even as new tools were brought to the task (for example, voice tapes to memorize foreign phrases), the enhancement of human intelligence has been modest. Until the computer came along.
Computers powerfully increased the ability of the human mind to exploit immense data collections, and vastly expanded the universe that our mind can penetrate with mathematical reasoning. These enormous enhancements of the human intellect have spread to nearly every country and continue to transform all fields of science. The recent progress in DNA sequencing, for instance, would have been impossible without powerful computers. It is true, and needs to be memorialized, that scientists and engineers performed prodigies in the nineteenth and first half of the twentieth centuries using only logarithmic tables, slide rules, and cumbersome mechanical calculators. The first powerful computers were built in the 1940s to meet demands of the Second World War, and since then the technology has graduated from vacuum tubes to transistors (in the 1950s) and silicon chips (since the1970s). It now appears nanotechnology might lead to another big step forward. The expansion of the mind’s mathematical and computational tools has had an impact on civilization almost as great as the invention of writing. It is as if the human mind—by creating computer systems—has pulled itself up by its own bootstraps to higher levels of intellectual capacity.
Leading computer scientists, ever since their vacuum tube machines, expressed confidence that computers will eventually be able to do all the mind’s intellectual work without reinforcement by a living brain. That goal, clearly, has not been reached, despite enormous advances in the science and technology of computers. But the ambitious goal has stimulated a branch of computer science, referred to as Artificial Intelligence, which developed specialized systems that can perform extraordinarily useful tasks. Signal achievements are computers that recognize and categorize patterns (fingerprints and human speech); read, store, and categorize text; perform language translations; and “learn” by adjusting to new information. Although computers do this work much faster and far more reliably than humans, they remain inferior to humans in carrying out many essential tasks—for example, developing new concepts and theories, anticipating political events, interpreting large-scale social trends.
Most computer scientists who sought to develop a machine that would rival human intelligence have used only electronic, mechanical, and other lifeless components. It is easy to see why. Unlike the squashy human brain, computers can be disassembled and put together again, their components can be altered and tested again, and the growth of their capabilities during the last fifty years has been greater than the growth of the brain’s intellectual capability during hundred thousands of years. To be sure, scientists working on Artificial Intelligence seek to learn from the brain. Ray Kurzweil, an accomplished inventor of advanced types of pattern recognition, predicts that the brain will be “reverse engineered,” both in its hardware and software, so as to achieve a more powerful “machine intelligence.” But even this audacious approach would be
