Tag Archives: podcast

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.

SZZ2C7MMNW2B

Uniquely you: Why babies are all different

I was listening to last month’s edition of Naked Genetics presented by Kat Arney, a podcast under the excellent Naked Scientists umbrella.

An interesting question was asked: if half the chromosomes come from a person’s father and the other half from the mother, why aren’t siblings simply identical twins born at different times? In other words, what mechanism controls individuality?

Dr Phil Zegerman provided a nice answer (listen from 25:04):

http://ec.libsyn.com/p/1/0/3/10347f3b4ced3abb/Naked_Genetics_12.08.14.mp3?d13a76d516d9dec20c3d276ce028ed5089ab1ce3dae902ea1d01cc8033d9ca54afd9&c_id=4824544

The transcript can be found here (‘Why are children all so different?’).

You can also watch this lovely animation of the process Dr Zegerman describes – meiosis:

And this is what it actually looks like in a fruitfly:

The influence of early eating habits in children

Our little one, who is now 10 months old, seems to have got his eating sorted after a stubborn start. We started weaning around the World Health Organization’s recommended 6-month mark, using a mix of spoon feeding and baby-led weaning (more on that in later post). Since then, it has seemed apparent that some things have gone down better than others: scrambled eggs, yoghurt, cheese, toast, chicken, bananas and strawberries were all early hits, while broccoli, tomatoes and beef were swiftly rejected.

He seems to have developed an appetite for some foods after a unsure start, such as cucumber, carrot and apple. And this brought to mind a Naked Scientists podcast from a few months ago, which featured an interview with Marion Hetherington, Professor of Biopsychology at the University of Leeds, on children’s appetite and eating behaviour.

The full transcript is available here and the audio is available here. I’ve made a few summary points below, but do check out the full interview.

  • A developing foetus can encounter tastes and odours derived from the mother’s diet and toxins from the environment, and this may affect later food preference.
  • Babies fed with breast milk are exposed to a greater variety of flavours than are formula-fed babies, and this can mean they are more willing to try new tastes.
  • Babies are primed to accept sweet tastes from birth, whereas bitter tastes are rejected. This means that we have to learn to like bitter foods but not sugary foods.
  • Parents may need to try their baby 8-10 times with a new flavour before the child will accept it, so parents shouldn’t give up after the usual 2-3 times. Also, there may be a sensitive period between 6-9 months in which to introduce new flavours and textures, after which it becomes harder for the child to accept a new food.
  • If a child of school age is fussy about trying new foods, then using rewards and social praise is an effective way of persuading them to test new tastes.
  • Setting healthy eating preferences early on is best to keep healthy eating going into childhood. Even if eating habits go awry in teenage years, many return to their early healthy eating habits as adults.

I thought this raised some interesting points, such as the persistance needed to introduce new tastes during a sensitive time window, and was worth highlighting.

It’d be interesting to know how these environmental factors interact with genetically influenced preferences, such as whether early exposure to broccoli, sprouts or cabbage can moderate the repulsion certain people have towards a compound in those foods. It has been suggested that ageing, smoking or illness may modify this genetically based food preference, and so it would be intriguing to know whether child eating behaviour did so too.

The journey begins…

The spur to start more formally chronicling my scientific take on parenting came from my agreeing to do a report for the excellent Pod Delusion podcast. The report centred on the unsolicited and unsubstantiated advice my partner and I encountered during her pregnancy.

It was a pretty awesome experience becoming a dad for the first time:

Jerry Coyne – evolutionary geneticist and author of ‘Why Evolution Is True’ – wrote recently on his blog about experiences akin to those attributed to a higher power, in which the sheer awesomeness of an event can bring about a sense of transcendence but separate from anything supernatural or religious, and this was definitely one of those for me.

As someone with a scientific background, I have always been driven to take a rational, critical look at claims. But now with a child to look after, things seem more weighty:

I could trust that millions of years of evolution has provided me with a paternal instinct that will kick in as and when needed, thereby ensuring that the fitness of my offspring will be increased. However, with such responsibility, ‘winging it’ is a little scary [and …] I would like to know the decisions I make as a parent have the backing of more than a ‘gut feeling’ or the instruction of age-old religious doctrine.

I felt as though of lot of the unsolicited advice I had received was supported by mysticism, hearsay or anecdotal evidence. I could also see some biases creeping in:

Many of these intuitions get perpetuated by a massive confirmation bias – all the people who guessed a boy said “I told you so, I just knew it, the way you were carrying that bump it must have been a boy”, whilst the other remaining half, who had predicted a girl, remained strangely silent and seemed to forget their prediction altogether.

I mentioned this because it is apparent when it comes to psychoanalysis:

there’s a wealth of cod psychological theories to explain someone’s personality with proponents retrofitting individuals who conform to these ideas to support their claim, whilst ignoring all other individuals who don’t.

I could also see some beautiful examples of some common logical fallacies: correlation does not mean causation, sample sizes and statistical power, absolute risk vs. relative risk, and reporting and recall biases. Listen to the report for more details.

My science-trained mind would almost always lead me to query claims, as any critical thinker should:

Whenever I tried to enquire about the evidence or statistics behind a particular claim or point to evidence that – say – there is scant evidence that more births occur during a full moon†, that familiar glazed expression would appear and a cursory muttering of “trust the scientist” might be offered.

†[Interestingly, it seems as though progression through the menstrual cycles leads to variations in the sex ratio, but this of course is unconnected to lunar cycles].

But I realise that it gets very difficult when one is actually placed in the situation of caring for child:

People often want a cast-iron guaranteed to-do list of what to do and what not to do, but scientific guidance rarely works like that. One can make a recommendation on the best available evidence, but those recommendations are liable to change and attitudes and practices need to be flexible enough to shift too. My mum, for instance, listening to the pervading advice at the time, slept me on my front to reduce the chances of Sudden Infant Death Syndrome through choking, but evidence since then has accumulated that shows an increased risk of cot death with front-sleeping and now babies overwhelmingly are slept on their backs.

And I do definitely value experiential advice, but I also appreciate that what works for one baby does not necessarily work for another. I guess that that was my motivation to look towards empirically validated advice to guide us during our rollercoaster, and so I concluded a few things I have picked up already:

  1. Be wary of any sentence that starts, “They say that…”*
  2. Do as I do, not as I say. There is a wealth of evidence that children who witness their parents carry out a particular behaviour – such as smoking, violence, even academic work – are more likely to behave in that way as adults.
  3. Open and honest attitude towards sex. Despite what Nadine Dorries may perpetuate, evidence suggests that when parents take a more positive attitude towards sexuality it can be beneficial for a child’s comfort with their own sexuality. And religiosity appears to have little impact on sexual risk-taking – the bigger influence is parental affection.
  4. Strike a balance. Musical training can be beneficial in attention, cognition, and language development. Early take-up, higher parental support, practice, and friendly rather than technically able music teachers all help, but there is evidence that successful childhood musicians need teachers who are ‘not too relaxed’ but ‘not too pushy’.
  5. And don’t read Mumsnet.**

*[I didn’t elaborate in the recorded report, but normally “they say that…” is followed by something that one person once said, that was based on a sort of hunch which may or may not be generalisable].

**[a cornucopia of anecdotes, ‘just-so’ stories and madly evangelical parents].

So that was my first formal attempt at verbalising some of the thoughts and ideas that came to me during a fairly tumultuous time. I wrote and recorded it during the first couple of weeks of our child’s life, so any glaring errors I will blame on sleep deprivation. More shall come as I look ahead to rearing this bundle of squidge.

[Note: more links to original studies will be added].