Hacker News new | past | comments | ask | show | jobs | submit login
How much a baby is touched leaves measurable effects on DNA methylation (2017) (miamiherald.com)
181 points by wyndham 51 days ago | hide | past | web | favorite | 90 comments


I have three children - and all are intelligent, beautiful well adjusted kids. 5, 7, and 15.

One thing I made a point of as each was born - I maintained as much physica contact with each immediately after birth. I didnt allow them to leave or be examined without me there, touching them.

I did it not for the posted reasons, but just beacuse it felt right to me.

ALso - I would hum and sing to them a tune while they were still in the womb.

As soon as they came out, I held them and sang and hummed the same tune to them. It immediately calmed them - with my first, she immediately relaxed and stopped crying whil the nurse took her vitals, measurements and pricked her heel.

It was magical.

> I did it not for the posted reasons, but just beacuse it felt right to me.

It probably felt right because it's natural. Newborns pretty much stayed with their mothers 24/7 for all of human history. This is true for chimps ( our closest ancestors ) and even our common ancestor. It's only recently with the push to get women into the workforce where women were encouraged to separate from their newborns so that they could go back to work.

> As soon as they came out, I held them and sang and hummed the same tune to them. It immediately calmed them - with my first, she immediately relaxed and stopped crying whil the nurse took her vitals, measurements and pricked her heel.

The mother's voice also helps premature babies develop. The fetus probably has gotten accustomed to the mother's voice in the womb and associates it with comfort and safety. Perhaps it's an evolutionary relic since many newborn animals are drawn to their mother's voice and vice versa.


Human babies also learn the pre-constructs for the languages being spoken around them while still in the womb, so no reason they can't learn other repeated noises.

Not sure how much it is related, but I learned how touch has a powerfully lasting impact when I read about babies from an underfunded Hungarian orphanage having lots of health problems later in life because of how little they were touched.

Seems very probable that an underfunded orphanage will have other areas like healthcare, sanitation and nutrition lacking as well. Was there something specific about what you read that related to touch?



This was something I quickly found. I can't seem to find the very article I read however.

Years of neglect is quite a bit broader than just touch. I would expect years of neglect in early childhood to have a long lasting effect on the mental development of kids.

I believe you may be referring to the Romanian orphanages after the Ceasescu communist regime.


Reading, too. My wife and I read to our two boys when she was pregnant with them and they loved book time almost immediately, even though they slept through it for the first month or two.

Fast forward and we have one 4 and one 7 years old and they are obsessed with reading and would do it every waking hour if we'd let them.

Here's another magical experience. No one will believe it, but it's true, so here goes.

We too would read, sing and hum to my son in-womb. While doing so, we'd occasionally hear a loud click, the source of which we couldn't determine. But after he was born, we found out. He would press his tongue hard against the roof of his mouth then release it with a suction "pop". Was he trying to communicate back to us from the womb? We like to think so!

I don't think this would work without air.

Maybe it can. It's called cavitation.

Are fetal tongues strong enough to induce cavitation? Are fetal mouths strong enough not to be shredded by cavitation bubbles collapsing? AFAIK cavitation kills a ship's screw sooner or later.

Cavitation can develop with wide range of energies. In this case, I'm suggesting energy level sufficient to create an audible sonic click, but not high enough to rip infant's head off.

> He would press his tongue hard against the roof of his mouth then release it with a suction "pop".

This is an alveolar click, known as a normal part of certain African languages.

If you've seen the name "!Kung San" around, it is the sound indicated by the "!K".

Same click.

Our 8 week old will cry if she is not held 24/7. Whilst it is incredibly tiring and hard work, we've found a way to make it work.

The epigenome isn't some mystical thing, it's just a manifestation of the environment on cellular function. These kinds of sensationalist articles are exquisitely frustrating as a genomicist.

You need to give that knowledge time to spread. The vast majority of living adults learned in school that the DNA is fixed and the surrounding stuff is just junk. Eventually everyone will know about epigenetics but how else would you spread the information if not with articles like these.

A few months ago, I spoke to my uncle, who's an endocrinologist at a medical school, and when I told him "Your organs are different because of epigenetics" a lightbulb went off in his head. I think outreach is just doing am awful job of explaining epigenetics. Even his colleagues in genetics hadn't really been able to explain it very succinctly.

Instead, articles are full of explanations like this one, leading you to make outlandish conclusions. Hell, even in one of my community outreach events, a farmer came up to me afterwards and said he doesn't want to grow any crops with methylated DNA.

The article never claims that it's mystical...why do you say it's sensationalist?

How long are epigenetic changes supposed to last? Do changes caused by trauma last longer than slower changes?

Every single specific thing that a differentiated cell does (which are most cells in the organism) are technically due to "epigenetics". Epigenetics just means that there are mechanisms to activate some genes and deactivate others. This is the essential core process in differentiation, as well as in many other processes in the body. It is like asking how long do differences between your skin cells and neurons is supposed to last?

It's very hard for a non-expert in the field to estimate the correlation vs. causality fallacies in a study like this.

I have some background to understand this (bioinformatics Honours), but am not an expert. What I can say is that the study at this point, if based on DNA methylation, does not even suggest that the effect is of physical contact is positive (to be Devil's advocate, the DNA methylation from physical contact could have a negative effect).

The study does ask for indicators (crying, behaviour, etc.) but with those parameters you can already try to correlate a lot of physical contact vs. less contact.

They are trying to tell whether methylation is worth studying (at all) in the context of more vs. less contact with your child. Personally, for the purposes of raising a child, I don't think these studies say anything at all. It's more important to stop panicking about nonexistent threats that social media wackos will try to convince you of.

Epigenetics is a very interesting field of study and is like a downtuned Lamarckian inheritance all over again. Things like chronic inflammation are still far from well understood. The body is like having 2 000 000 000 years of Wikipedia and all its edit history crammed into one string of DNA letters. And now we learn that apparently metadata (the DNA methylation) is also crammed into the whole thing and even that changes all the time.

By the way, for that matter, what constitutes "affectionate physical contact" quantitatively is not clear to me. I think each child's particular emotional need at any time is really difficult to pinpoint. I had a great childhood and parents, but I think that I always had a sort of angst (maybe competitive angst?) that really can't be said to be anyone's fault. These days if you feel funny and go the psychologist they will probably say: "Don't worry. It's just appropriate affect. If you spend 15 hours a day on Instagram then you are supposed to feel funny."

This is an example of the sort of cases in which I worry that experts become clouded by zealotry; I think it's more likely that a generalist-at-a-distance will poke the right holes in the methodology of these kinds of studies.

I wonder why they don't have independent statisticians review each paper doing statistics? Seems weird and abusable that only people from the same subfield reviews the papers.

It's hard enough to find reviewers in the same field. I imagine finding statisticians to review papers from fields they don't care about would be problematic. You probably know that reviewers work for free.

IIRC DNA methylation (sp?) is used in blood tests to determine the rate at which you are aging biologically. This article does claim that the children who are touched less develop at a slower in addition to having a lower DNA methylation. So in a sense, the less a child is touched, the slower the child ages biologically according to this marker and observation.

Anecdotally, there are environmental situations where animals can significantly increase life-expectancy but at the expense of delayed sexual maturity.

It would be interesting, but of course not conclusive, to see if these children experience puberty later and if they also live longer. Perhaps some neglect has some benefit.

Being touched is an undeniable signal you are surrounded by the tribe, which triggers the reproductive sequence, since it takes a village to raise a child.

That would make a good sci-fi - an army of sociopaths that live until they’re 200 years old.

Star Trek II The Wrath of Khan is basically this.

Except babies die if you don't touch them.

Actual study this article is referencing:



Animal models of early postnatal mother–infant interactions have highlighted the importance of tactile contact for biobehavioral outcomes via the modification of DNA methylation (DNAm). The role of normative variation in contact in early human development has yet to be explored. In an effort to translate the animal work on tactile contact to humans, we applied a naturalistic daily diary strategy to assess the link between maternal contact with infants and epigenetic signatures in children 4–5 years later, with respect to multiple levels of child-level factors, including genetic variation and infant distress. We first investigated DNAm at four candidate genes: the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), μ-opioid receptor M1 (OPRM1) and oxytocin receptor (OXTR; related to the neurobiology of social bonds), and brain-derived neurotrophic factor (BDNF; involved in postnatal plasticity). Although no candidate gene DNAm sites significantly associated with early postnatal contact, when we next examined DNAm across the genome, differentially methylated regions were identified between high and low contact groups. Using a different application of epigenomic information, we also quantified epigenetic age, and report that for infants who received low contact from caregivers, greater infant distress was associated with younger epigenetic age. These results suggested that early postnatal contact has lasting associations with child biology.

Even if this result is real (I smell bad statistics), it's completely useless.

All cells in our bodies have the same genome. But a hepatozyte and a neuron are very different cells, aren't they? The difference is that cells specialize, and they do so by selectively methylating their genome (not the only mechanism, but an important one), thereby modifying the expression of genes. So a liver has a very different epigenome than the brain of the same person. Now here we're looking at a study of the saliva epigenome, apparently the most important tissue they could come up with.

Then they don't analyze the epigenome in any interesting way. Generally, the more a cell specializes, the fewer genes are active. Expressing this as "more mature" is rather dumb. "More geriatric" would be equally appropriate. Does it not matter at all, which genes are methylated?

So, let's summarize the study properly:

"If you don't touch your child enough, his saliva with age more slowly."

Can you back up your implication that the saliva epigenome has no other meaningful and impactful correlates?

Why do you expect me to prove a negative? These "scientists" (really just tinkerers) need to argue for their implicit claim first.

But they don't. They take the (correct, but hardly useful) statement "methylation generally increases with age" and instead say "with maturity" to make it sound impactful.

Not too surprising that earliest experiences in life are going to color an individual's expectations of the world, and how to respond to it.

"consequences on the epigenome" as the article so charmingly puts it.

> "consequences on the epigenome"

Indeed such a stupid phrase. Any dynamic activity in the body, every process or change which happens due to dynamic actions during life is technically a consequence on the epigenome, because it requires some cells/organs to change some chemical reactions, produce more of this stuff and less of that stuff - it requires activating some genes and deactivating other genes. You drink tea - it has consequences on the epigenome. You think happy thoughts instead of sad ones - it has consequences on the epigenome... You excercise - it has consequences on the epigenome...

Your talking about the epigenome has consequences on the epigenome.

I think there is a high chance that is 100% bullshit.

Most likely has to do with confusing cause-and-effect.

It could be just as well that highly methylated babies cry more and could be more demanding or parents with highly methylated babies are themselves less tolerant to crying thus end up handling babies more.

The problem, they way it is being reported, and they way it lines up with pseudo-scientific mumbo-jumbo groupthink makes it stink. That's why it is newsworthy. People want to believe that handling a baby will change their DNA.

Same bullshit like papers like this:

- Scientists Say They’ve Found a Code Beyond Genetics in DNA - https://www.nytimes.com/2006/07/25/science/25dna.html

>I think there is a high chance that is 100% bullshit.

I haven't read the paper this article is based on, so I can't comment on the study or the reliability of the results.

However, epigentic effects related to the degree of maternal touch have been convincingly demonstrated in naked mole rats in crossover studies. I posted about this research previously. (https://news.ycombinator.com/item?id=18749285)

One thing that we know from decades of twin studies is that childhood family environment explains a vanishingly small percent of long-run adult outcomes.

Contextualizing this single study's result against the much larger, more established evidence from twin studies strongly suggests that one or more of the following is true.

- The results are spurious and won't replicate.

- The results are true, but the association is not causal, and is simply proxying correlation with an upstream factor.

- Lack of touch does lead to methylation in the short-term, but by adulthood there's strong reversion to the mean.

- The methylation has no significant impact on any actual metric that we care about like success, health, personality or wellbeing.

There are issues with twin studies, not the least of which the number of twins raised separately, but not adopted, is tiny. However adoptive parents are a small self-selected subset of the population.

Most twin studies simply compare identical and fraternal twins in non-adopted households.

Since identical twins share twice the genetic covariance of fraternal twins, the impact of family environment can be backed out from the respective intra-pair correlation coefficients. In the limit case if genetics played no factor, then fraternal and identical twins should have identical pairwise correlations.

For example suppose pairs of identical twins have 45% pairwise correlation for adult IQ. And say fraternal twins have 25% correlation for the same measure. That would tell us that the population level variance of adult IQ is 40% attributable to genetic heritability, 5% to environmental heritability , and 55% to non-heritable factors (i.e. not genetics and not family environment).

In case you're interested, IQ is much more heritable than that for adults. The following quote is from Wikipedia:

"Twin studies of adult individuals have found a heritability of IQ between 57% and 73%[6] with the most recent studies showing heritability for IQ as high as 80%[7] and 86%.[8]. IQ goes from being weakly correlated with genetics, for children, to being strongly correlated with genetics for late teens and adults. "

Right, those studies can tell us about heritability, but cannot distinguish between common environment and genetics.

Why would parents of twins pay much more attention to one than the other?

Maybe because, for whatever reason, one cries a lot more than the other?

But that would be an edge case. I would have assumed that identical twins behave similarly. How do they find enough neglected twins to make a reliable conclusion.

I’ve known three sets of identical twins. In each case the personalities were very different. Outgoing vs reserved, aggressive vs laid back, etc. I could easily see one wanting to be held more than the other.

Anecdotal, but... My (fraternal) twins have very distinct and different personalities. One requires an order of magnitude more attention than the other. We try to make up the difference, but it's hard.

It's not vanishingly tiny, simply small.

Can you think of a reason selection bias could be an issue, thus invalidating twin study cohorts?

Adoptive parents are people who have gone through a lot of effort and expense to get their children, so they're far more likely to be heavily invested in their kids. It's also expensive so they're likely to have money. If the effects of parenting are strong, but "cap out" -- i.e. above a certain level of care, parenting does little, but before that level it has a strong effect -- then twin studies will show little of that effect.

I'm not sure I follow the causality argument here.

A twin study should normalize everything genetically. Ergo epigenetic expression and environment are the only two causal levers. It sounds like you're arguing that parental involvement has a causal impact, which is the point of the studies to a degree.

Perhaps my original question was unclear: is there something the twins do or have done to them that cause a latent selection bias before adoption, thus invalidating the twin studies approach as a whole?

We are questioning how much the parenting has an affect on the child. The parents are self-selected and so are more likely to be similar to each other.

Agreed. That was my point. Not all twins under adoption are adopted, meaning there is nothing particularly invalidating about the twin study framework.

I don’t know. I have read this before. But this goes so much against my gut feeling and what I have experienced that it is hard to believe. It’s counter intuitive to say the least.

The documentary Three Identical Strangers also agrees with you, a fascinating account of triplets separated at birth to study parenting.


I'm not a professional scientist, but shouldn't the spirit of science be curiosity and exploration at all times, not shooting down a new idea as soon as you hear it?

If such an attitude were present in every person, science would not progress at all.

I'm not that long a veteran here, but I think at HN we are more interested in having our minds and ears open and feeling we can comfortably share and discuss articles that make us think, than fostering an attitude like this.

I mean this with respect, whoever you are.

I think that science works best if we marry two mindsets: the joy of seeing something novel, and the suspicion of seeing something too good to be true. They don’t have to be present in equal measure for every article, and while I wouldn’t word it the same way as the parent, I appreciate the healthy skepticism on this topic.

Yes: a good reasoner is charitable and critical. You need both.

That's great for a classroom setting, or in the lab, or wherever people are forming hypothesis. But in articles communicating research, accuracy matters. You can believe in the value of creative thinking and also want article that do a good job describing research.

This is about junk science - that is the true danger and bottleneck to science - that reward for making unsubstantiated but grandiose claims. These do far more damage than potentially unfair criticism.

I am a scientist by profession and I have come to believe that the majority of work in this field is wasted because people chase that 5-minute fame. Once you are in the field you can smell the stink a mile away.

It always sounds the same: "A second genetic code discovered", "Touch reflected in the DNA", "Next cure for cancer", "Scientists can edit now genes at high fidelity with CRISPR" all pure bullshit.

This article is terrible and did the grave disservice of not mentioning the work that has been done on this front using rats. Obviously, we cannot ethically reproduce the RCTs in humans to establish cause and effect, but there's sufficient evidence to form hypotheses and spur investigation in humans. I'm having trouble finding the exact primary literature that I wanted to cite just now, but here are a couple of things worth looking over:



scientific study: "The importance of touch in development", Brain Research Centre and Department of Psychology, University of British Columbia, Vancouver. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865952/#__ffn_... (as commented elsewhere)

most certainly, I would fully agree that touch is an important ingredient to socialization and stimulation -

it is the premature claim that it changes DNA what is so annoying and misleading.

because once something changes your DNA it suggests that it is there forever (that is why it captures people's imagination)

Not if it is the methylation of DNA, modulating the expression of that DNA...methylation is frequently modulated by experience.

That study is only reference to the existing consensus, not the actual study from the OP.

I don't have the time to dig out the actual study but it looks like [1] it's originating in Canada (not NIH/USA) based on the publication of the press release.

Original comment of thread doesn't understand how much research is behind this idea (touch linked to higher outcomes long-term). I'd strongly recommend the commenter to read tribler's citation as that's scientific consensus at this point. If you want to read the recent study on DNA affects of touch, then below is that source of research.

1 - https://www.med.ubc.ca/news/holding-infants-or-not-can-leave...

I have performed DNA studies in my career. Measuring and interpreting methylation - understanding what it is, why, when and where it is present is at its infancy at best.

Sadly I have prime view how clickbaity ideas like this one drive most of the motivations behind investigations in life sciences.

It is not just this paper that is bullshit, the whole field of "epigenetics" that this paper is a representation of is bullshit as well - this paper is just one out of the long line.

As I pointed out it there is simply no proof that handling changes DNA. It could just as well handling stimulates the development rate which, in turn, also shows up as another signal.

The lie is not that A and B are present at the same time. The lie is presenting story as if A was caused by B. There is absolutely no evidence for that.

Now hundreds of scientists want a piece of the "cool" story, will jump headfirst into proving how LOVE will reflect in the DNA. No one will care about understanding what the heck is methylation - they will all be chasing baby handling and methylation. That's what I have seen happening and will keep happening thanks to papers like this.

> is at its infancy at best.

Hence why the main source is published with ~90 subjects studied. Science starts with one paper/experiment and builds from there.

> The lie is not that A and B are present at the same time. The lie is presenting story as if A was caused by B. There is absolutely no evidence for that.

That's not a lie. It's called a hypothesis. It's testable. They've tested it and encourage others to test as well.

I will tell you what they did. They collected data, with no hypothesis or any idea what they are looking for, then desperately fit various models until something showed up as statistically significant.

Of course, you could say: how dare you, how would you even know, ... I work in this field, the p-hacking, harking (hypothesizing after the results are known) is both pervasive and endemic. they massaged the factors, the genders, the ethnicity, the socioeconomic status etc until the model did something that was publishable.

It simply not possible to accurately correlate these two measures: self-reported minutes of touching a baby with the methylation levels of the DNA of that baby - if you are serious about accounting for all the possible variations across all factors

A perfect example of what I am talking about. What is the final conclusion of that paper written in 2009!:

> Are the neuroendocrine effects of these experiences across the lifespan also mediated by DNA methylation? The answer to this question is not yet known.

So what happened in the following ten (!) years, have we finally figured out whether the effect is mediated by DNA methylation? Nah. Instead, they published another bullshit paper, this time about babies being held...

Ten years is (or rather should be) an eternity in science! The 1st smartphone was barely released back then - how far have gone in technology in this time? Yet we are nowhere closer to have proven or disproven the mechanism. Instead, they would much rather maintain the status quo and publish another bullshit paper.

Just a small caveat. When I quit my PhD (computational protein folding models) in 1987, it was because I didn't want to spend 10 years working on a problem and getting nowhere. Turned out I was wrong - way too optimistic!

Until the recent ML-based announcement from Google (and maybe not even with that in hand), protein folding research went nowhere for at least 30 years. So I wouldn't be too critical of a 10 year gap.

I think they forgot to say being more touched probably means parents are more close by, more caring. Why would you not touch a baby if you are constantly close by? So probably not BS, just a study say is right, but not for all the right reasons.

To add to that, there are so many problems with self-reported studies.

> They also asked parents to keep track of how long and how often they gave care to their child that involved physical contact, according to a press release.

N = 100, and all of the physical contact data seems to have been reported through journaling by the parents. I wonder if that data is actually reliable.

Wait... Does our DNA change as we age??

If so, to only sample the DNA after the study and not before seems crazy.

The article is talking about methylation, which I always interpret to mean they're referring to the epigenome. It doesn't change our DNA, so much as the expression of it.

How much state is in the expression of DNA? Will all this type of state be lost eventually, or is there also persistent state in the expression of DNA?

The field of study is called Epigenetics [1]. I know practically nothing about it, but it seems that some of these alterations to the expression of DNA are not only persistent, but can also be inherited. Which is why some of these discoveries have been called a revenge of Lamarck over Darwin...

[1] https://en.wikipedia.org/wiki/Epigenetics

Epigenetic markers that appeared during the potato famine and Great Depression have been found in grandchildren of those who lived it.

There's also evidence healing from trauma can change expression.

What do you mean by persistent state?

So, just how mutable is the DNA? For the sake of the discussion, I don't know anything about DNA that I can say I didn't get from a sci-fi flick.

There's a special thing called "Epigenetics". The genes coded in DNA don't change. But how they're used can change.

There's methyl groups that attach to the DNA. These stop parts of the DNA being read.

There's Histones which wind up your DNA and control how much can be read.

These are used control which parts of DNA are used by which cells. Evey cell has the same Genome, but each cell needs a different program to function, so changing the Gene Expression you get a different kind of cell.

These are not mutations. They're more like tags.

I initially misread as "How much a baby is touched _by_ leaves [leaves] measurable effects on DNA."

Leaving me with an idle question: has the effect of interaction with plants on child development been studied?

Ditto :D

This interview sounds like unpublished bullshit, it would never stand reviewing. To claim this from the survey they conducted is just wrong. Every science student learns about the difference between causation and correlation.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact