The human baby’s remarkable ability effortlessly to acquire language is only one line of evidence for the biological basis of language. Have you ever noticed how difficult it is to learn a second language the older you get? For example, I do not seem to be readily able to learn a foreign language and it is not through lack of trying. Despite hours of effort with Linguaphone learning tapes, I am unable to break the British stereotype of only being able to speak English. This is because the plasticity in the neural circuits in my brain that support language learning has been progressively lost. Some of us do not have such a problem but it may be related to whether we were exposed to other languages at a young enough age. This is one of the reasons that foreign-language learning is much easier before the age of seven. For example, when Korean immigrants to the United States were tested on their ability to learn English, individuals had no problem if they arrived before they were seven. For older immigrants, it became increasingly hard for them to learn English, even though they attended night classes and were highly motivated to learn.28 This indicates there are biological limits to learning languages.
For many, just hearing the difference between languages becomes hard. In a classic study, Canadian infant researcher Janet Werker demonstrated that all babies could hear the different sound structures that exist in spoken Inuit and English languages before the age of ten months. However, the longer they were immersed in their own language environment, the more difficult it was for them to hear differences in the structure of other languages.29 As we age, we lose the ability to detect the subtle differences between spoken languages. The best explanation is that our brains are tuning into the experience from our environments and losing the ability to process experiences that we do not encounter. Our brains are becoming less plastic for language learning. This is why, for Japanese speakers, English words that have ‘l’ and ‘r’ sounds are often confused, which can lead to comical miscommunication. Pinker wrote about his visit to Japan where he described how the Japanese linguist Masaaki Yamanashi greeted him with a twinkle in his eye when he said, ‘In Japan, we have been very interested in Clinton’s erection.’ This was several years before the US President would face impeachment in 1998 due to the Monica Lewinsky scandal.
Windows of opportunity exist in language and, as we shall see, even extend into other human qualities. But before we look into this, we should exercise against caution in over-interpreting the research on brain plasticity and critical periods described so far. This is because the discovery of critical periods in many animals led to some extreme beliefs and practices about human plasticity, especially when it came to how we should raise our children and what was the best parental practice. During the 1990s, there was a general panic that we were raising children in impoverished environments. The fear was that if we did not expose our children to a stimulating early environment, especially during the first three years, they would end up brain damaged. Suddenly, there was a public appetite for infant brain training and every parent and grandparent felt compelled to buy brain-enhancing devices from jazzy mobiles to hang over the crib, videos and DVDs to stimulate the brain, tapes of Mozart to play to pregnant mothers30 and every other kooky notion that was ‘proven by research’ to improve your child’s chances of getting into one of the Ivy League or Oxbridge universities. The marketers even had the audacity to name their various products Baby Einstein and Baby Bach. John Bruer, then director of the James S. McDonnell Foundation that supported much of the neuroscience research behind the original animal work, even wrote a book, The Myth of the First Three Years, to try to counter this hysteria based on the over-extrapolation of animal deprivation studies to human development.31
The truth is that deprivation has to be quite severe before permanent loss occurs because most daily environments are sufficiently complex to provide enough input for hungry young brains to process. Parents should not be conned into thinking that they can enhance a process that has taken millions of years to evolve. In fact, some products such as baby training DVDs to enhance language have been found actually to impair language development because parents were relying on the television rather than the richness of normal social interaction.32
Concerned educators and shrewd companies have either naively or deliberately misinterpreted the extent to which brain plasticity operates during sensitive periods. More importantly, there is little evidence that we can improve upon Mother Nature to supersize the early learning environment for a better intellectual outcome. But such messages fall on deaf ears. When it comes to doing what’s best for their kids, most parents err on the side of caution and so I suspect that the baby-brain boosting industry will always flourish. If only they would understand that the human brain has not evolved to absorb information from technology, but rather to absorb information from other people – much more complicated and yet so familiar.
The Gossiping Brain
At around 1.5 kg, the human brain is thought to be around five to seven times larger than expected for a mammal of our body size, and it has an especially enlarged cerebral cortex.33 If our brain had the same architecture as a rodent, it would weigh just 145 g and hold a meagre twelve billion neurons.34 Why do humans have such big, complicated brains in the first place? After all, they are very expensive to run, and although they only account for 2 per cent of typical body weight, they use up 20 per cent of metabolic energy.35 It has been estimated that a chess grandmaster can burn up to 6,000 to 7,000 calories simply by thinking and moving small pieces of wood around a board.36 What could justify such a biologically expensive organ? An obvious answer is that we need big brains to reason. This is why we can play chess. After all, a big brain equals more intelligence. This may be true to some extent but evolutionary psychologist, Robin Dunbar, has been pushing a less obvious answer – one that has to do with being sociable. He makes the point that big brains are not simply useful for any problem such as chess, but rather seem to be specialized for dealing with problems that must arise out of large groups in which an individual needs to interact with others.37
This is true for many species. For example, birds of species that flock together have comparatively larger brains than those that are more isolated. A change in brain size can even occur within the lifespan of an individual animal such as the locust. Locusts are normally solitary and avoid each other but become ‘gregarious’ when they enter the swarm phase of their life cycle. This swarm phase of the locust is triggered by the build up of locusts as their numbers multiply, threatening food supply, which is why they swarm to move en masse to a new location. As they rub against each other, this tactile stimulation sets off a trigger in their brain to start paying attention to each other. Amazingly, areas associated with learning and memory quickly enlarge by one third as they begin to swarm and become more tuned in to other locusts around them to become a devastating collective mass.38
Larger brains facilitate social behaviour. The link between brain size and sociability is especially true for primates where the extent of the cortex predicts the social group size for the species even when you take body mass into consideration. For example, gorillas may be big primates but they are fairly solitary animals with small close-knit family units and so their cortex is comparatively smaller than that of chimpanzees, which are much more sociable and like to party.39