meal matters as much as hunger in determining how much we eat.
For most of us, though, the food memories that really matter go much further back. You may not be able to remember what you had for lunch last Tuesday, but I bet you can recall the habitual meals of childhood; the breakfast you were given for a weekend treat and the way bread tasted in your house. These are the memories that still have emotional force years or even decades later.
Such memories, conscious or unconscious, are what drive us to seek out the old habitual foods – particularly packaged foods – even if, judged objectively, they do not really taste nice or do our bodies any good. There have been experiments done with rats and mice where the animals are given dopamine blockers, drugs that interfere with the part of the brain that governs reward. These drugs take away much of the chemical reward of eating food. Yet the dopamine blockers do not extinguish the rodents’ food-seeking behaviour, at least not straight away. At first, the animals continue to press the lever (or run through the alleyway, or whatever the task might be) and eat the pellets, even though the dopamine blocker means that the food no longer offers the same gratification.8 Next, they carry on pressing the lever to earn the pellets, but do not eat them. Finally they stop pressing the lever, indicating that at last their desire for the pellets has gone. The interesting thing is that it takes so long for the desire to fade. As the neuroscientist Roy A. Wise has observed, it is only when ‘the memory of the reward is degraded through experience that the desire is lost’.9 The craving for the pellets is more a function of memory than of how they taste. Memory propels human food urges in much the same way. As we traverse the supermarket aisles in a trance-like state, we are like rats in an alleyway, steered to this or that food by memories of rewards long gone.
One of the reasons that we do not usually think of our tastes as learned is that most of the learning tends to happen in the very early years of life; and then it stops. For those of us who believe in personal development, it is depressing to learn that a person’s food ‘likes’ aged two generally predict their tastes at twenty. In 2005 researchers in Turkey interviewed nearly 700 undergraduate students and their mothers.10 The mothers were asked about their children’s eating habits when they were two and the students were asked about how they ate now. There was a remarkable continuity between then and now. The students who were ‘picky eaters’ as children still described themselves as picky eaters. The ones whose mothers recalled that they always ate too much still did so. And the three people in the study who ‘never’ ate vegetables as children still had no vegetables in their diet. So much for putting aside childish things.
When we talk of memory and food, we generally assume that nostalgia is a phenomenon that occurs late in life – like Proust being transported to his youth by a madeleine dipped in lime-blossom tea. But food memory is there from the start. Even babies have nostalgia! It’s a large part of how we learn to eat. The foods parents give to babies provide them with powerful memories that trigger lasting responses to certain flavours. This process begins before birth. We are all born with echoes of our mother’s diet, which mean that no one is a totally blank slate when it comes to flavour. We arrive predisposed to respond to certain foods by our experiences in utero.
It’s hard to know what a newborn thinks about taste, since we can’t exactly ask them. Or rather, they can’t exactly answer. But in 1974 the Israeli doctor Jacob Steiner realized that a baby’s reactions to the basic tastes of sweet, sour, salty, bitter could be gauged by their facial expressions, which are vivid and mobile, even in the first week.11 Steiner took babies just a few hours old and offered them a range of tastes on a cotton swab, filming their facial expressions. When given salt, which you’d think might make them cry, the babies surprisingly showed little reaction, continuing to look expressionless (a liking for salt only emerges later, around four months). But all the other basic mouth-tastes produced strong reactions. The sour swab made the babies pucker their lips. Bitterness provoked an expression of abject distress and an open mouth, as if trying to spit or vomit it out. As for the sweet swab, Steiner found that it produced a dreamy look of ‘relaxation’ with an ‘eager licking of the upper lip’ and even a ‘slight smile’ – and this at an age when babies are not supposed to be capable of smiling. Such is the power of sugar.
The test has since been repeated many times, with similar results. What it confirms is that, as we have seen, all human babies, from Sweden to China, have a strong innate preference for sweetness and a dislike of bitterness and sourness. Basic tastes are not a question of memory: we are hard-wired to think sweetness is wonderful and that bitterness is scary. No one has to learn these simple tongue-reactions. But flavour is another matter. Flavours – these memories generated backwards through our nose – are all learned. What we think about flavour in all its myriad forms, from toasted cumin to sea bass, from parsley to spaghetti carbonara, is not fixed. Each of us will have a different bank of memories and feelings about these; and it exists from day one, if not before.
Taste buds appear at seven or eight weeks of gestation. Already, by thirteen to fifteen weeks, the taste buds are mature. A thirteen-week-old foetus weighs maybe an ounce, with no fat under the skin, no air in the lungs. Yet already they can not only swallow but taste, and these sips of fluid leave memories.
In 2000 some French scientists did a remarkable experiment showing that newborns arrive in the world with a memory of how their particular amniotic fluid tasted.12 The mothers studied came from the Alsace region where strong-tasting anise sweets are a local delicacy. Some of the women had eaten anise regularly during pregnancy and some had not. The babies were tested straight after birth and four days later, having tasted nothing outside the womb but milk. When an anise odour was wafted in front of them, the babies born to anise eaters showed a marked and ‘stable’ preference for anise. They turned their heads towards the anise smell, sticking their tongues out with a licking gesture. They remembered it and apparently it pleased them.
Further experiments have confirmed that other strong flavours such as garlic can also find their way into amniotic fluid. In one study, women agreed to swallow garlic capsules forty-five minutes before they were due for an amniocentesis; when it was tested, their amniotic fluid smelled garlicky.13 Babies born to voracious garlic eaters will have been floating in a sac of garlic water for nine months. It has been shown that babies exposed to garlic before birth are more likely to enjoy garlic in food later on. Likewise, mice whose mothers had been fed on artificial sweeteners when pregnant had an exaggerated taste for sweetness.14 Pregnant rats fed on junk food – including savoury snacks, sweetened cereals and chocolate-hazelnut spread – had babies who also selected these foods over regular rodent pellets, though the babies’ preference for junk was lessened if the mothers switched to a healthier diet during lactation.15
The flavours our mothers ingest most regularly can become like mother’s milk to us. Julie Mennella and Gary Beauchamp are biopsychologists working at the Monell Chemical Senses Center in Philadelphia who have done a series of experiments on how flavour in utero and in breast milk leaves children with lasting memories and preferences for certain foods.16 One of their most celebrated studies, from 2001, involved carrot juice. The babies of a group of mothers who drank carrot juice during the last trimester of pregnancy and again during the first two months of breastfeeding were predisposed to like the flavour of carrot. When the babies were weaned onto solid food, several months after the mothers stopped drinking the carrot juice, they showed a marked preference for cereal flavoured with carrot juice over plain cereal flavoured with water.
The early exposure of babies to flavour – both in utero and through milk – works as a kind of ‘imprinting’, as Gary Beauchamp puts it.17 We become emotionally attached to these early aromas. As we saw in Chapter One with the ‘flavour window’, younger babies are more open than older ones to new tastes. When it comes to weaning, this is an argument for ignoring the advice on exclusive breastfeeding for six months and offering early, varied bites of vegetable purées between four and six months. When it comes to the pre-food stage, however, flavour may be one of the strongest arguments for mothers attempting to breastfeed, at least for the first few months, to eat as varied a diet as possible while doing so. Some psychologists suggest that instead of saying to mothers: ‘breastfeed for the baby’s good’ healthcare advisers should say: ‘breastfeed for your own good’