Tag Archives: child development

Does a rub or a cuddle relieve pain?

I suspect most parents will have been there with a little one – a fall, a knock, a misfired football, and then the tears. In a bid to relieve the hurt, you give the sore a good rub, a strong cuddle or maybe a peck to ‘kiss it better’.

But why? Does a rub genuinely relieve pain, or is it just the only thing we can think of to show we care?

What is pain?

First, we need to understand what pain is.

Our skin and tissues underneath have different types of nerve cells coarsing through them. These help the brain sense the environment by signalling touch, temperature, pain, depending on what the fine nerve endings are set up to detect. Some nerve cells, for example, are studded with molecular receivers that grab chemicals wafting over them or change shape with varying temperature, while others fire when bent, stretched or vibrated.

When stimulated, the nerve cell pings an electrical signal down to our central nervous system, which then uses all the messages to interpret what’s going on in the environment and elicit the most appropriate action.

A gentle touch or a warm fire, will trigger our mechanoreceptors (touch) or thermoreceptors (temperature) and we may experience a nice fuzzy feeling. Pain receptors, technically known as nocireceptors, have a high threshold for stimulation. So we feel pain when certain stimuli – temperature, pressure, chemical – are intense enough to trigger the high threshold nocireceptors, which fire off signals that our brain processes as “too hot”, “too hard” or “too irritating”. This helps us take immediate action (‘move away!’) and means we generally learn what’s safe and what’s not. And while it might seem attractive to not feel pain, it causes serious problems if it isn’t there – individuals without this sense are prone to chewing chunks of their tongues off or to frequent bone breaks.

What shapes the feeling of pain?

One idea of pain relief says that stimulating the mechanoreceptors with a rub ramps up the ‘touch’ signals being sent to the central nervous system, which at least partly overrides the input from the nocireceptors. Known as the ‘Gate Control Theory‘, this shifts the balance of sensation from ‘pain’ to ‘touch’ – in a way, distracting our central nervous system with another stimulus.

There is also a special class of slow-acting touch nerve cells, triggered by gentle stroking, which seem to signal pleasurable sensations. Some studies suggest that these interact with the pain pathway to dampen painful sensations.

As well as the signals from the body, the brain coordinates input from other processing centres, which allows us to take into account past experience, from where on the body messages are being received and the context in which the stimulation is happening. Maybe that’s why a hug from a loved one can feel extra comforting.

And chemical signals in our brain shape our feelings of pain. Endorphins are chemical signals that are natural opiates so, like morphine and other opiates, can block painful sensations. They are also released in response to stress and fear, and bring the energising and euphoric feelings after exercise. Sometimes their effects are powerful enough to completely override the pain, which can be why people who have been shot sometimes only feel pain after the fearful situation has ended.

The relief of a rub

So what we actually feel is a physical and emotional experience after the brain processes the various sensory signals from the body, and takes into account past experience, environment and mood.

These may be some of the reasons why a good hug or rubbing a painful area can bring some genuine relief from hurt.

 

What can Mickey Mouse tell us about a growing child?

At a party some time ago, I got talking to a biology graduate friend about comparative psychology, as a geek tends to do at social occasions.

Comparative psychology is the study of animal behaviour and mental processing across different species. By doing this, it gives us clues to the function, benefit and development of a particular behaviour. Understanding the similarities and differences amongst different animals in this way can shed light on evolutionary relationships.

The topic came up because our friends were revelling in how cute baby animals are. If you don’t believe me, just look at these cherry-picked examples:

Author: George Estreich

Baby monkey

Author: Ville Miettinen

Baby fur seal

Author: Matt Stanford

Baby elephant

Author: uaeveggies

Baby duck

What’s striking is how wildly different baby animals can provoke the same “aaah” reflex. Baby primates and baby birds, separated from each other and from us by millions of years of evolution, can elicit the same cooing reaction. And size doesn’t seem to matter − a 100kg baby elephant can bring as much infatuation as a 5kg baby seal.

In other words, there’s something about being a baby, and not just a miniature version of an adult.

This immediately reminded me of an image drawn by Nobel prize-winning animal behaviourist, Konrad Lorenz. It shows how juvenile proportions are conserved across different animal groups, and goes someway to explain why we react to many baby animals as we do.

From Studies in Animal and Human Behavior, vol. II, by Konrad Lorenz, 1971. Methuen & Co. Ltd.

From Studies in Animal and Human Behavior, vol. II, by Konrad Lorenz, 1971. Methuen & Co. Ltd.

I think I first saw this image in a book by renowned evolutionary biology, Steven Jay Gould*. He also included it in a wonderful essay called Homage to Mickey Mouse. In this article, Gould explains that over time, to chime with his softening of character, Mickey’s appearance became increasingly juvenile.

via Zoonomian

A large head relative to body, short legs and feet, bulbous cranium and big eyes, as seen in a latter-day Mickey, look like the hallmarks of a juvenile. And Mickey travelled this path to juvenility in reverse − a phenomenon known as ‘neoteny‘.

An illustration’s fine, but to truly demonstrate this scientifically, Gould actually measured the relative changes in Mickey’s physical attributes and plotted the results on a graph. The result, as was Gould’s wont, is an engaging fusion of science and creative writing − do read it. (On reading, I did wonder whether Mickey’s appearance was altered to match a desired change in character, or the other way round.)

The key to all this is that the proportions of a baby’s face, as compared to an adult, are similar across many different animals. This set of features triggers what Lorenz described as an ‘innate releasing mechanism’ − an automatic and consistent reaction to an important behavioural cue. It makes sense that a hard-wired mechanism has evolved to trigger an immediate sense of attachment when confronted with a baby’s face − it will promote parental care, which has clear evolutionary advantages.

But that same hard-wired mechanism also appears to fire when we see similar baby-ish proportions in other animals. It’s an inappropriate response in an evolutionary sense, but it’s better to be harmlessly fooled by a baby bird than to not feel instinctively drawn to our own baby.

What’s fascinating is that, in some cases at least, these ‘releasers’ are reduced to very specific features. A classic example was demonstrated by Lorenz’s Nobel prize-winning collaborator, Niko Tinbergen, using three-spined sticklebacks. A male stickleback will attack another male, as identified by a red belly, but will also attack any object with a red spot − fish-shaped or otherwise. A stickleback-shaped object without a red belly is suitably ignored. Like a red rag to a stickleback, it’s better to be safe than sorry.

Babies do something similar in reaction to stylised smiley faces − a circle for a head, two dots for eyes, and a curved line for a mouth is enough to grab a baby’s attention. This stays with us into adulthood and is, for better or worse, the reason why emoticons are so enduring. So, similar to a stickleback reacting solely to a red spot, it seems it’s not a whole baby’s face we respond to, just a certain set of features.

Yes, your baby’s cute because of this graph:

“At an early stage in his evolution, Mickey had a smaller head, cranial vault, and eyes. He evolved toward the characteristics of his young nephew Morty (connected to Mickey by a dotted line).” By Steven Jay Gould

* I should dedicate this post to the late, great Derek Yalden, who taught me zoology at The University of Manchester and told me to read The Panda’s Thumb.

(As an addendum: none of this makes animals we find cute any more ‘worthwhile’ than “ugly” animals. Check out the recent campaign by the “Ugly Animal Preservation Society“.)

How to engage a baby

When you share a laugh with your baby, it can be one the warmest feelings as a parent. But is this a genuine mutual exchange, and how does it come about?

This is a video of what is now a classic experiment in developmental psychology. It shows a mother happily engaging face-to-face with an equally happy baby. The mother then ceases all facial engagement – the “still face” – to which the baby reacts by trying, with all its might, to reestablish the happy interactions. It’s quite a marked and powerful effect:

A historical review of the experiment quotes the researchers who first documented the effect:

“the infant first “orients toward the mother” and “greets her expectantly.” But then, when the mother “fails to respond appropriately,” the infant …

… rapidly sobers and grows wary. He makes repeated attempts to get the interaction into its usual reciprocal pattern. When these attempts fail, the infant withdraws [and] orients his face and body away from his mother with a withdrawn, hopeless facial expression.”

The experiment, in this form, was first presented at a scientific conference in 1975, but it wasn’t the first to document what happened when infants are exposed to varying social interactions. It was, however, the first to use “then-novel videotape technology” on the conference hall’s big screen. Adamson and Frick, in their historical review, suggest that the  immediate and dramatic illustration of the phenomenon contributed to the broad interest this experiment gained. An early lesson in the power of ‘modern’ technology for effective science communication and to maximise research impact.

This may all seem a little obvious to some parents. You may feel that you don’t need a psychologist with a video camera to tell you that a baby is happiest when you are engaging them face-to-face. But there are a number of reasons why the methodical description of this effect has had profound and lasting influence.  

What this experiment first showed, by deliberately manipulating the parent’s engagement, was that the baby is an active player in this exchange. The infant’s social behaviours can influence the parent’s level of engagement, just as the parent can influence the baby, and it can subtly alter these depending on the context. It’s not simply the parent reacting to the baby’s randomly generated cues. It has even been detected in babies as young as a few weeks old.

As Jason Goldman at The Thoughtful Animal says:

“The still face experiment demonstrated that very young infants already have several basic building blocks of social cognition in place. It suggested that they have some sense of the relationship between facial expression and emotion, that they have some primitive social understanding, and that they are able to regulate their own affect and attention to some extent. The infants’ attempts to re-engage with their caregivers also suggest that they are able to plan and execute simple goal-directed behaviors.”

But one reason why this experiment has been so important and enduring is that it provided a standard and reproducible way of measuring children’s social emotional development.

By using the same set-up time-and-time again, it has shown how a child’s social and emotional development becomes richer as they grow older. The response becomes increasingly complex with age, and can include deftly timed facial cues, dampened smiles, sideways glances at their parent and yawns. Adamson and Frick cite a lovely example for the original set of experiments in which a five-month old boy, upon encountering a still face, stopped being wary and…

“…looked at the mother and laughed briefly. After this brief tense laugh, he paused, looked at her soberly, and then laughed again, loud and long, throwing his head back as he did so. At this point, the mother became unable to maintain an unresponsive still face.”

An experience I’m sure many a parent can relate to when – armed with a stern face – they try earnestly to tell off their child, only to be met with a cheeky grin or giggle!

The experiment has also allowed researchers to deconstruct these parent-baby social interactions into visual, auditory and tactile components. Vision and hearing, it seems, is especially important as children get older, but touch can be enough to, at least partially, lessen an infant’s anxiety when confronted with a still face.

Nevertheless, a still face is usually enough to produce the basic negative reaction in a child, even if it’s in response to their mother, father, a stranger or someone on television. Children make a distinction, however, for inanimate objects, even if they appear quite human-like, demonstrating their ability to form genuine social relationships.

This experimental set-up has also revealed possible negative consequences of a parent’s still face. According to Adamson and Frick, children actually show a more dramatic reaction to a still face than to a brief period of separation or to situations in which the parent interrupts interactions to talk to a researcher. Babies assimilate and react to a negative social cue, rather than simply becoming distressed at the lack of stimulation.

The “still face” experiment has shown its use in further understanding various developmental disorders, such as Down’s syndrome, deafness and autism, as well the effects of environmental conditions like infants exposed to cocaine prenatally or to depressed mothers.

The still face experiment has been used to ask questions about how early social and emotional engagement may affect later behaviour. The strength of an infant’s still face effect has been linked to their mother’s normal sensitivity and interactive style, and it may predict the degree of later infant attachment, depression or anxiety, and even behavioural problems.

Clearly, parents who may have a lower level of engagement, such as those experiencing postpartum depression, should not be guilt-tripped, especially as this could have an exacerbating effect. But the still face experiment has shown that simple procedures can help in these situations – depressed mothers who are encouraged to provide more touch stimulation are often able to offset the lack of visual or auditory engagement to bring about more positive social interations.

As Ed Tronick – one of the original researchers of the “still face” experiment – says on his website:

“An infant’s exposure to “good, bad, and ugly” interactions with the mother, as repeatedly communicated by her facial expressions or lack of expression (i.e., a still-face) has long-term consequences for the infant’s confidence and curiosity, or social emotional development, with which to experience and engage the world.

Though let’s not forget the role of fathers, or other partners, either.

[Thanks to mum-in-law Jenny (once again) for the video and @matthewcobb for the Adamson and Frick article]

Should babies watch TV?

This question seems to trouble many parents, and can cause a lot of guilt too.

“Will the TV numb my baby’s brain?”

“Are they destined for a sedentary life?”

“AM I CONDEMNING THEM TO LIFE AS A MINDLESS AUTOMATON?!”

This is why an interview last week with psychologist Annette Karmiloff-Smith on the BBC’s The Life Scientific caught my ear (thanks to a pointer from mum-in-law, Jenny). It’s a fascinating insight into how babies learn to learn, and how their brains develop to understand the world around them. You can listen here: The Life Scientific.

But on TV watching, Prof Karmiloff-Smith, an expert in developmental disorders, argues that if the subject matter of the programme is carefully chosen and scientifically based, then the TV can be better for a child’s learning than even a book.

This was largely in response to advice reissued by the American Academy of Pediatrics (AAP) that babies under two shouldn’t watch any TV or DVDs. There are three main concerns: poorer language skills, a negative effect on sleep, and less time spent taking part in other types of unstructured play that are critical for the proper development of mental capabilities.

This is based on a growing body of scientific research. TV/DVD watching is common: in the US at least, by two years old over 90% of children regularly watch TV, spending an average of 1-1.5 hrs a day in front of the box. Very young babies (under 1.5 years old) cannot, however, really understand TV programmes, and are instead mainly attracted by obvious changes like applause or visual surprises.

Children learn new words or actions better when an adult is teaching it to them live, rather than via a television screen, and the worry is that parents talk to their kids less when the TV is on. And a growing number of studies suggest that children who spend longer watching TV/DVDs have delayed language development, at least in the short-term, and may also develop a worse attention span.

A child’s play may also be hindered by the distraction of a TV that’s on in the background, so the AAP advise to turn it off altogether. Many parents also use TV/DVDs as a sleep aid, but there is evidence that bedtime viewing may lead to more disturbed and shorter sleep.

Karmiloff-Smith, on the other hand, argues that we live in a media saturated world and it’s unrealistic to expect parents to shut down all media use. This view has support from some of the evidence cited in AAP report itself. Despite the original recommendation in 1999 that parents should be discouraged from letting their babies watch TV/DVDs, over 90% of them in the US currently do so by the time their child is two years old. What’s more, the average age that TV is introduced is 9 months, so the advice is clearly not striking a loud enough chord.

From my experience, I can certainly appreciate this. The AAP report says that many parents use the TV so that they can have a shower or cook dinner. Absolutely! Even these seemingly mundane activities can feel like an exercise in military-like efficiency when you’re looking after a child. A 10-minute respite when they’re quiet and content gazing at a TV or prodding an iPad can be just too tempting.

It’s also interesting to consider that throughout history many new technologies have been treated with caution. Dr Vaughan Bell, a psychologist based at King’s College London, has highlighted how the printing press, popularisation of the radio, and now the Internet have been damned for ruining kids’ brains.

Karmiloff-Smith goes on to say that, rather than banning TV for babies, TV programmes just need to be made better and based on science developments. For instance, the visual system is attracted by movement, but most kids’ TV programmes have their focus on the centre of screen. Instead, objects and features that come in from the sides, move across screen and encourage the child to interact promotes the active participation that’s good for mental development. For very young babies, moving image media may even have advantages over books, which are static and whose main attraction is the rustling of the pages.

The caveat in this is that Karmiloff-Smith reveals herself to be a scientific consultant to a DVD company that is designing such programmes. This could cause suspicion of a financial conflict of interest. But her honesty and gusto make me suspect that she became a consultant so that she could promote these ideas, rather than the other way around.

She finished the interview by emphasising that parents still need to interact with their children and the TV shouldn’t be used as a babysitter. But we should think more carefully about which types of media can stimulate the visual and auditory systems, so as to help train the attention and memory systems early.

I’ve written before about the various kinds of programmes and the various contexts in which kids can watch TV, which may have different effects on child development. And some of the evidence cited in the AAP report highlights these complexities. The effects on children’s attention, for instance, seem to depend on the programme content and style, with problems seen not when the content is deemed educational but only when it’s geared towards entertainment. And when a parent watches a programme with an infant and talks them through it, the child tends to become more attentive and responsive. The AAP report also points to evidence that watching Sesame Street can have a negative effect on expressive language in children under two. But the same study showed that watching other programmes, such as the North American-based shows Dora the Explorer, Blue’s Clues, Arthur, Clifford, or Dragon Tales, was associated with greater vocabularies and higher expressive language scores. So it appears that not all ‘screen time’ is equal.

The AAP report seems to fall into the trap of treating all TV and DVD viewing as the same:

For the purposes of this policy statement, the term “media” refers to television programs, prerecorded videos, Web-based programming, and DVDs viewed on either traditional or new screen technologies.

Another major limitation of the AAP report is that all of the cited studies are, by necessity, observational. These investigations are good at highlighting whether two factors are associated with each other, but they cannot tell you whether one causes the other. As the report itself asks, are children with poor language skills simply placed in front of the TV more? Are children with shorter attention spans more attracted to screens? Are parents who are less attentive on the whole, more prone to resort to screen time? If so, then turning the TV off would not necessarily lead to more parent-child interactions.

And some results are just contradictory. One study in the US showed that when the mother’s educational status and household income were taken out of the equation, the association between TV viewing and poor language development disappeared. This appears to have been glossed over by the AAP.

So how do I answer my original question?

The AAP are right to caution against a lot of TV for under twos (over four hours a day, say), as this is when the damaging effects are really apparent. But Karmiloff-Smith is also right to say it’s unrealistic to expect no TV at all, and that the right programme in the right environment is fine and potentially beneficial.

And I’ll leave you with this quote in Time from Dr Dimitri Christakis, a paediatrician at Seattle Children’s Hospital:

Ask yourself why you’re having your baby watch TV. If you absolutely need a break to take a shower or make dinner, then the risks are quite low. But if you are doing it because you think it’s actually good for your child’s brain, then you need to rethink that, because there is no evidence of benefit and certainly a risk of harm at high viewing levels.

Parenting science: 12 top stories of 2012

It’s that time of year when we’re flooded with ‘best of’ lists, so allow me to jump on the bandwagon. 2012 has been a great year for science – the discovery of the Higgs Boson, the landing of Curiosity rover on Mars, and the ‘encyclopaedia of DNA’ that has given us the deepest insights into the human genome.

Here, I’ve picked out some of the stories that might interest parents, covering areas such as child learning and development, reproductive technologies, embryology, genetics, and even a bit of public policy thrown in. I’m sure I’ve missed some interesting ones too, so please add yours in the comments!

Mouse eggs created from stem cells for the first time (New Scientist)

Once a fully functional body cell develops from a ‘parent’ stem cell, it’s thought there is no going back to the previous state. A team of scientists in Japan, however, used a cocktail of signalling molecules to reprogram skin cells to become immature egg cells in mice (they had already done this to create sperm cells). What’s more, these cells could be fertilised and, in some cases, led to healthy mouse pups. This was a stunning feat of biological engineering that will help in the study of mammalian development and also hold promise in treatment of infertility. In a related story, controversy over whether biology textbooks need to be re-written took a turn when more convincing evidence was published that the number of eggs in a female isn’t fixed for her lifetime but can instead by replenished from a stem cell stock.

‘Chimera’ monkeys created in lab by combining several embryos into one (The Guardian)

The headline is pretty self-explanatory and the article itself is a fascinating read, so I won’t re-invent Ian Sample’s superbly crafted wheel. So if you want to know more about the controversial technique of creating normal, healthy monkeys with cells from more than one embryo and why it might benefit stem cell therapies, go read it! This may not be as bizarre and ‘unnatural’ as it first sounds, though, as we may all be walking chimeras and carry cells from siblings, aunts and uncles.

Genome Sequencing for Foetuses (Wired Science)

Being able to test foetuses for genetic faults that increase the risk of a serious disease, such as Down’s syndrome and blood or nervous system disorders, is hugely important. This is currently done mostly by invasive techniques such as taking samples of the placental tissue or amniotic fluid. This study, however, showed that it’s possible to work out the foetus’ genetic make-up by piecing together tiny fragments of DNA floating around in the mother’s blood. The ease of such a test would, of course, raise ethical issues about what is appropriate to screen for and what counselling parents would need, as well as requiring a firm and clear communication of risk.

DNA-swap technology almost ready for fertility clinic (Nature News)

Mitochondria are little energy powerhouses within most of our cells and they contain a small amount of their own DNA that is inherited wholly from the mother. A range of devastating diseases, that can affect the brain, liver, muscle and many other organs, are caused by defects in this mitochondrial DNA. A group of US researchers showed it was able to swap the mitochondria in a mother’s egg with one from a healthy donor to produce a normal looking embryo free from the mitochondrial genetic faults (restrictions on this technology would not allow a live birth). You can read about how the scientists actually did this in David Cyranoski’s article. And I would add that, contrary to some scare stories, these would not be ‘3 parent babies’ – mitochondrial DNA contains only 37 genes (involved in protein synthesis and biochemical reactions that make up respiration) compared with the many thousands of genes coded for by the DNA in the nuclei of our cells.

Babies are born dirty, with a gutful of bacteria (New Scientist)

Earlier this year I blogged about the “The microworld that lives inside you” and how the microorganisms that outnumber our own cells 10:1 are first transmitted from mum as a baby is born. A study by Spanish scientists, suggested that this isn’t the whole story. By studying the “meconium” – the baby’s first poo that is made up of materials ingested during the time in the womb – they detected two types of well developed bacteria. We don’t know for sure, but these were probably passed from the mother through the placenta. Our so-called “microbiome” is really important, because it influences our digestion, immune system, risk of disease, and maybe even our personalities.

Childhood stimulation key to brain development, study finds (The Guardian)

A US study provided more evidence that a sensitive period of learning and development exists early in childhood. They surveyed children from when they were four years old, recording details such as the number of books and the types of toys they had, to measure the amount of mental stimulation to which they were exposed. They also scanned the brains of the same children when they were between 17 and 19. As Alok Jha explains: “…the more mental stimulation a child gets around the age of four, the more developed the parts of their brains dedicated to language and cognition will be in the decades ahead.” Of course, this was an observational study and so limits the strength of the conclusions about whether the types of toys really caused brain developments, but the way the researchers tracked the same children over many years and the factors they took into account (parental nurturance had little effect, for example), was particularly impressive. Another cautionary note: the results were presented at a scientific conference and, as far as I know, have not appeared in a scientific journal, which means it won’t have yet been properly quality assessed by experts.

Golden ratio discovered in uterus (The Guardian)

At the risk of straying into mysticism, this was a nevertheless alluring report of a Belgian gynaecologist’s claim that the uterus represents an aesthetically pleasing “golden ratio”. This ratio is derived from something called the “Fibonacci sequence”, which is a sequence of numbers starting 0,1,… where every subsequent number is the sum of the previous two (so: 0, 1, 1, 2 , 3, 5, 8, 13, 21,…). The ratio between pairs of number in the sequence (divide one by the other) ends up being 1.618, which is the “golden ratio”. As Alex Bellos explains, its devotees believe it expresses aesthetic perfection and is found wherever there is beauty. According to Dr Verguts, when women are between the ages of 16 and 20 and at their most fertile, the ratio of uterine length to width is 1.6, spookily close to the “golden ratio”.

What happens to women denied abortions? This is the first scientific study to find out (io9)

Another set of results presented at a scientific conference, rather than in a scientific journal, but that is worth noting nonetheless. Annalee Newitz cites a Facebook post written by the lead researchers of a study that followed up women who had sought abortions at different abortion clinics in the US: “We have found that there are no mental health consequences of abortion compared to carrying an unwanted pregnancy to term. There are other interesting findings: even later abortion is safer than childbirth and women who carried an unwanted pregnancy to term are three times more likely than women who receive an abortion to be below the poverty level two years later.” Newitz further emphasises the preliminary results: “When a woman is denied the abortion she wants, she is statistically more likely to wind up unemployed, on public assistance, and below the poverty line.” If these findings turn out to be valid when further quality checks are carried out, they could help shape the debate on abortion policies and the state support a women seeking an abortion receives.

Boys and girls may be entering puberty younger (New York Times and The Guardian)

A study on the timing of puberty in boys by the American Academy of Pediatrics complements an earlier study on girls, which both hinted that puberty is, on average, starting gradually earlier in both sexes. Current estimates, at least for US children, are that the average age of puberty onset is around 9 years in black boys and girls and around 10 years in white boys and girls (although full sexual maturity may happen later than this). No one, as yet, knows why, but speculations include diet, changes in physical activity, improvements in healthcare, and chemicals present in the environment that affect our hormones.

Fathers bequeath more mutations as they age (Nature News)

A Swedish study concluded that a father passes on more genetic mistakes to their children than do mothers, and the older the man, the more mutations he is likely to pass on. This is most probably explained by the fact that sperm are generated from dividing ‘precursor’ cells throughout a man’s life and this cell division becomes less precise with age. Most inherited mutations won’t lead to any problems for the child, but the occasional one may increase the risk of a genetic disease like autism or schizophrenia. Taken together with rising average age of fatherhood, does this help explain, at least in some part, why autism rates are rising? (It could, but awareness and diagnostic changes are also likely to be at play). It’s not definitive and it shouldn’t scare older would-be fathers, but it may help in better informed decision-making.

An HPV Vaccine Myth Debunked (New York Times)

One of the arguments opposing vaccinating children against the Human Papilloma Virus (HPV), which can cause warts and cancer, is that in the minds of the young girls it frees them up to be sexually more promiscuous. Studying long-term medical data from girls in Atlanta, USA, however, showed no difference between vaccinated and non-vaccinated girls in pregnancies, sexually transmitted diseases, testing for sexually transmitted diseases, or contraceptive counselling. The article finishes by saying: “As one expert said, parents should think of the vaccine as they would a bicycle helmet; it is protection, not an invitation to risky behavior.”

Hungry mothers give birth to more daughters (Nature News)

Another eye-catching story was the report that during the Chinese Great Leap Forward famine, the proportion of boys being born dropped (from 109 boys for every 100 girls to 104 boys for every 100 girls). This sets up the tantalising possibility that sex ratios are adjusted in response to environmental conditions such as nourishment, a situation already known in deer where undernourished males tend to have fewer offspring than undernourished females (although in humans other factors like psychological and physical stress could be at play).

A final story that caught my eye was the latest results from the Avon Longitudinal Study of Parents and Children (ALSPAC), also known as the Children of the 90s, which probably warrants a blog post in itself. Nature News covered it and The Guardian’s sublime Science Weekly podcast featured it too (after 26:10). My favourite bit was how they collected the children’s milk teeth: “We had to negotiate for those. They are worth money to children, after all. In the end, we only got the milk teeth when we presented each boy and girl with an official Alspac form, signed by the tooth fairy.”

How sweet!

The microworld that lives in you

From a pod near you

I love a podcast. Episodes of audio goodness are delivered daily or weekly to my MP3 player, ready to keep me company on my long commute. I subscribe to podgrams dealing in current affairs, football, history and comedy.

But the overwhelming amount of disk space is taken up by science. Scientific news, scientific scepticism, scientific ideas, science in culture and scientific history. Even science comedy. Science science science.

Sometimes issues related to pregnancy and childbirth, childhood and parenting crop up, which as a science-minded parent is right up my street. And, I hope, right up other people’s streets too.

Here are some nuggets with which to start.

Ed Yong on BBC Radio 4’s Four Thought | 19 Oct 2011

Science writer Ed Yong describes his fascination with the human ‘microbiome’ – the bloom of microbes that each of us house in and on our body. The cells of bacteria, fungi and other microorganisms actually outnumber the cells of the human host by 10 to 1, and their genes by 100 to 1. Are we humans hosting a microbial community or a superorganism in which human cells are simply partners?

We can’t function as we do without these microbes. They help to digest complex foods like carbohydrates, metabolise drugs and toxins, interact with our immune system, and affect energy balance. The types and numbers of microbes within each of us are different and can depend on diet, environment and behaviour. The microbiome may have even played a part in shaping our evolution. They have such an important role that the microbiome has been called the ‘forgotten organ’ or the ‘second genome’. How, then, would you define what is ‘us’ – is it any cell that contains the same DNA as when we were an embryo, or are the constantly interacting microorganisms that are vital to our survival ‘part of us’.

What’s really interesting, at least from someone interested in child development, is how we gain this microworld. As Ed explains in the audio clip, we develop in the sterile environment of our mother’s womb*. The first gift from our mum is a smattering of microorganisms, but this depends on how we are born. A baby born of a vaginal birth is delivered their birthday presents as they travel through the vaginal canal and slides past (brace yourselves) the mother’s anus. The makeup of bacteria in vagina of pregnant women is actually quite different from that in non-pregnant women. A particular bacterium, usually found in the gut where it helps digest milk, becomes far more abundant in the vagina during pregnancy, which may give the baby a healthy coating as it is born.

Babies born of a caesarian section, however, do not have this close encounter and instead pick up a different spectrum of bugs that more closely resemble the ones found on skin. It can then take a while for the full complement of gut bacteria to establish.

The community expands and becomes more varied as the child interacts with its surroundings. Breast milk has been found to contain up to 600 species of bacteria, which furnish the babies gut and hinder the growth of any harmful nasties. Babies are then ready to take in more complex foods. This in turn fosters a richer microsociety and the mutual relationship continues. Environmental contaminants and toxins can perturbe the microbial community, which has been suggested (though not proven) to contribute to type II diabetes, cardiovascular disease or obesity.

Kerri Smith on Nature Podcast | 23 August 2012

Kerri Smith on the Nature Podcast reports on recent research that shows how antibiotics, at least in mice, can affect the gut bacteria composition and, consequently, the amount of body fat. The antibiotics seem to spur the bacteria into producing more fatty acids, which are converted by the human host into fatty tissue. Listen from 05:45 – 11:35 to hear a discussion with one of the researchers on the study of antibiotics in early life and the possible link to obesity.

And another fascinating potential of our microbiome is discussed by Chris Smith on The Naked Scientists podcast. Listen from 16:30 – 20:55 to hear Dr Marcello Riggio talk about how certain bacteria can promote oral health (good!) but also lead to bad breath or tooth decay (bad). Skip to 21:00 to hear a debate with Prof Gareth Morgan on whether probiotics – beneficial bacteria supplemented in the diet – may help to prevent/treat allergies and gut infections by interacting with the host’s immune system (ends 26:30). This idea is, however, not fully supported by the current evidence: results are variable and inconsistent (see The Cochrane Library reviews on allergies, eczema, colitis and diarrhoea).

Chris Smith on The Naked Scientists | 5th Sep 2011

Click to listen to: The_Naked_Scientists_in_Africa

And, finally, an even more fascinating potential of our microbiome is discussed by Mo Costandi in his Neurophilosophy blog. The bacteria in our guts may have the ability to affect brain development and mood.

For more on the wonder of the microbiome, read Ed Yong’s excellent blog post and Carl Zimmer’s article in the NY Times.

*or, maybe not.

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Milking the (cash) cow?

Or, should I feed my one year old cow’s milk or infant formula?

The Skeptical Son is about to hit one year of age, which brings a few landmarks with it. MMR vaccination, standing up (albeit a little precariously), and a move from specialised (breast or infant formula) milk to regular, unmodified cow’s milk.

This latter point seemed pretty uncontroversial. The UK National Health Service and the American Academy of Pediatrics both recommend feeding cow’s milk to a baby beyond 12 months. The NHS explicitly states: “Infant formula, follow-on formula or growing-up milks are not needed once you baby is 12 months old”.

So I was intrigued to see infant milk formula products specifically targeted at the over one year olds, such as Aptamil 1+yr & 2+yrCow & Gate 1-2yr & 2-3yrHipp Organic growing up milk (from 12 months), and SMA 1-3yrs.

A look at the scientific literature, in line with the NHS and AAP guidance, backs up a move to cow’s milk at 12 months. Unmodified cow’s milk is not recommended before this age because it contains high levels of sodium, potassium, phosphorus, and calcium, and lacks vital nutrients, such as iron, vitamin C, and linoleic acid. As a baby’s diet becomes more varied and complex by the age of one, many of the nutrients previously gained from milk (breast or modified cow’s formula) is obtained from food. An infant can, in most cases, safely move to consuming cow’s milk, and it is only if a specific deficiency develops that they will need targeted supplementation.

http://www.flickr.com/photos/jelles/2902422030/

Cow by JelleS [CC-BY-2.0]

The NHS’s health information leaflet, however, says: “It is recommended that all babies aged from six months to 5 years are given a supplement that contains vitamins A, C and D, unless they are drinking 500ml (a pint) of infant formula a day (infant formula has vitamins added to it)”. This then brings us back to enriched infant formula.

The infant formula manufacturers appear obliged to acknowledge that breast milk is recommended for young babies (see disclaimer notice*), consistent with the World Health Organization’s guidance. All of them, though, promote their 1 year+ products as, variously, enriched with iron, vitamins C & D, GOS/FOS prebiotics and omega fatty acids. Advertising claims include milk formula that is “nutritionally superior” to cow’s milk, “has been specially developed to help meet the nutritional needs of toddlers”, and will “encourage your toddler’s natural friendly bacteria to thrive”.

So now I’m a little torn. Anaemia, avitaminosis and lactose intolerance are, evidently, serious conditions that need to be addressed, and products need to exist for these cases. But the marketing doesn’t seem in line with the healthcare advice: without looking into it, I was initially left with the impression that the specialised infant formulas represent the gold standard, containing everything that is needed to support my son’s “amazing development” [© Cow & Gate]. The adverts and packaging don’t suggest these products are for cases where a deficiency has been identified, rather it appears to play to the ‘don’t take any chances’ or ‘be on the safe side’ worry of parents. SMA, for instance, says “it is hard to know if they are getting all of the right nutrients they need at this important time”.

I guess this speaks to a wider problem with nutritional supplements, ‘superfoods’ and enriched dietary products, some of which make all manner of claims about health and well-being (see Andy Lewis’ Quackometer for more ‘Confusopoly of Diet’).

Anyway, now for a quick look at money, something that’s precious to many families. A 900g tub of Aptamil 1+ yr costs £8.49 (Sainsbury’s price). This means that a daily intake of 500ml will cost 79p (83.3g formula). An equivalent daily portion of whole cow’s milk costs 26p. Even adding in a multivitamin supplement works out at an extra 13p a day. Over a week this difference amounts to £2.80; over a year it’s a saving of around £145.

I should emphasise that the post-one year milk formulas seem completely legitimate products to sell and I’m far from claiming a conspiracy, but I explore it here simply to question whether their advertising is a little misleading. Of course, dietary products claiming all sorts of health benefits is not a new or isolated phenomenon, but I worry that the baby market particularly plays on the anxiety of parents that inclines them to prove themselves as perfect guardians.

Maybe I’m being overly cynical in suspecting that the manufacturers are being unreasonably opaque. Perhaps I’m too naïve in wishing that promotion of products that affect ours and our babies’ health was more honest. Would it be regulatory overkill to make infant formula products, in the same way as the breastfeeding disclaimer, carry an objective notice about cow’s milk and the current healthcare advice?

And on that ambivalent note, I shall end.

*The common wording across manufacturers’ websites and the prominent positioning of the statement (it is displayed any time one tries to click through to a product for the first time) suggests this is a statutory requirement. This would be interesting if it is, so any light that anyone can shed on this would be appreciated!