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Why Aren't We Smarter Already?

Dr Thomas Hills, Department of Psychology

Published January 2012

Science fiction films and novels have long speculated on the huge advances that humans could achieve with an increase in brain power, whether through evolution or pharmaceutical means. Dr Thomas Hills asks if it's so easy to evolve superior cognitive capacities, why aren’t we smarter already?

Still of Bradley Cooper in Limitless

Human bodies and brains have evolved over many thousands of years. Pharmacology offers a number of much quicker solutions for cognitive enhancement – Ritalin and Modafinil being just two. These drugs, licensed to treat medical conditions, work in a similar way to amphetamines. They can enhance focus and attention span. Some academics have suggested that we could medicate ourselves to be cleverer.

Goal-directed cognition looks at how we represent and pursue goals. Could popping a pill really be the answer? Can we cognitively enhance ourselves to benefit the world?

What the science fiction novelists and filmmakers tend to overlook in their superpower stories are the consequences of a drug or evolutionary change. Physical and mental health can be a trade-off.

“One common example is the rise in anxiety and loss of fine motor control often found following high doses of caffeine,” says Dr Hills.

Caffeine may keep us awake and alert, but to the detriment of our well-being and motor-control skills. With some drugs we might not know if there are any side effects or indeed what they are.

“It’s clear that in many cases we don’t know what exactly is happening in the brain,” Dr Hills says about cognitive enhancing drugs. “Part of the issue we have with pharmaceuticals in general is that it can take years to find out what the consequences are.”

People who have superior cognitive abilities pay for them with a trade-off.

“People who have superior cognitive abilities pay for them with a trade-off” according to Dr Hills. He gives the example of the Ashkenazi Jew population, where “the average IQ is approximately 0.7 to 1 standard deviation above that of the general European population … evidence indicates that this rise in IQ was the consequence of evolutionary selection for greater intelligence among European Jews over approximately the last 2,000 years.” The trade-off appears to be a rise in the prevalence of sphingolipid diseases, which are correlated with the same neural causes that render possible increased IQ, such as increased dendrite development. Evolution has kept a check on unsustainable developments.

“Cognitive traits have evolved under both ecological and physiological constraints… all known evolutionary trajectories inevitably run up against constraints that prevent such runaway selection. The costs eventually outweigh the benefits." In general Darwinian ideas about evolution suggest that animals adapt to their environment the best way that they can, given the constraints of that environment. Giraffes evolved longer necks to reach higher trees but also had to develop stronger hearts and deal with increased blood pressure. Therefore evolution produced a giraffe with a successful balance between neck length and blood pressure. Too long a neck and/or too high a blood pressure and the giraffe wouldn’t have survived to pass these traits on to the next generation and the traits would not have been beneficial to the species."

Similarly, there’s a trade-off in humans and their infants.

“You can’t just make a bigger brain without having consequences," says Dr Hills. “We are essentially evolutionary products of the constraints created by our environmental and bio-genetic histories. As living organisms, we are product of trade-offs made in response to these constraints.”

For example, for a woman to successfully give birth to a bigger-brained child, she would need a larger pelvis. As Dr Hills says, evolution has curtailed a baby’s brain size at the optimum point for both the baby’s developmental needs and the mother’s bipedal locomotion (ie ability to walk while pregnant): having a larger pelvis would affect a woman’s walking ability. Focusing on the trade-off, a bigger human brain would also require more nutrition, teaching and learning time.

“The categorical more-is-better assumption is false in relation to cognition,” concludes Dr Hills. “It can’t be true that more focus is always better and increasing it will solve everything. The mind is making this trade-off all the time… although the empirical possibility of a domain-general, cognitively enhanced ‘supermind’ remains - perhaps in response to cultural evolution - evolutionary theory would suggest it is extremely unlikely.”

  • Why Aren’t We Smarter Already: Evolutionary Trade-Offs and Cognitive Enhancements
    by Thomas Hills (University of Warwick) and Ralph Hertwig (University of Basel) is available free to download and read.

Thomas HillsThomas Hills is is the co-editor of Cognitive Search: Evolution, Algorithms, and the Brain. He is also an Associate Professor in the University of Warwick's Department of Psychology. His research focuses on the cognitive control of search processing in external and internal environments. This encompasses goal-directed behavior and its consequences for human memory, problem solving, and decision making. The evolutionary origins of thought provide insights into both what and how we think, and this is visible at the level of behavioral strategies shared across tasks, and the underlying neurophysiological control that is shared across animal species.


Bradley Cooper as Eddie Morra in Neil Burger's Limitless (2011). The film depicts an author who is made smarter by taking the pill NZT.