<![CDATA[INSIDE THE MIND OF KATHY DETTWYLER - Blog]]>Sun, 13 Dec 2015 11:22:27 -0800Weebly<![CDATA[Deconstructing Katie Hinde's Jan 17, 2015 blogpost "When to Wean"]]>Mon, 02 Feb 2015 15:49:08 GMThttp://kathydettwyler.weebly.com/blog/deconstructing-katie-hindes-jan-17-2015-blogpost-when-to-wean OK, so . . . manypeople have asked me to respond in specific detail to Katie Hinde’s blogcolumn, following on Barbara King’s NPR post on breastfeeding.  One colleague even accused me of being a“senior scholar in the field” and “bullying an untenured colleague” andimplying that I think Katie Hinde is an idiot. So, to clarify.

I do not think Katie Hinde is an idiot.  Not at all. I also do not think that being a professor at Harvard automatically makesanyone a “damn fine” member of their scientific field.  A number of highly respected professors atHarvard have been fired over the years for plagiarism and academicdishonesty.  Katie Hinde is NOT one ofthem.  The point remains that it is notlogical to claim that simply because someone is at Harvard their word must betaken as the definitive view on a subject.

Katie Hinde’s blog post is set up as a MYTH: vs. TRUTH:exercise.  However, many of her myths areeither what we like to call “straw men” – things no one really believes, orthey are indeed “myths.”  I’ve set thisresponse up as “What she writes” vs. “What the reality is.”

What she writes:  “When Barbara contacted me to providecomments for her thoughtful piece on very prolonged breastfeeding in responseto the Mirror’s report on Denise Sumpter and the accompanying brouhaha, Igroaned.” 

What the reality is:  By referring to Barbara King’s column asbeing a piece about “very prolonged breastfeeding” she gives us her first clueof her opinion on this issue. Opinion.  Not fact.  She thinks breastfeeding a 5-6+ year old is“very prolonged”.  In reality, it isperfectly within our best understanding of the range of weaning ages for modernhumans – 2.5 to 7.0 years (and yes, this is MY research, and NO, Hinde doesn’trefer to it or cite it).  There havebeen, and continue to be, many thousands of children around the world nursingbeyond the age of 3 years, which is usually the cut-off for “extendedbreastfeeding” as a descriptor to be applied. Many people object to the term “extended” even, and prefer ‘full-term”or “natural-term” breastfeeding, or simply “breastfeeding.”  To describe nursing a 6 year old as “veryprolonged breastfeeding” reveals a lack of understanding of how human behave,both in the historic and prehistoric past, and today in modern populationsaround the world. 

What she writes:  “Myth: Humans are adapted to wean at aspecific age. . .  

Sometimes folks will posit that this adaptive sweet spot isat 2 years old, at 2.5 years, at 4 years, 5 years, or some even 7 years.”

What the realityis:  No one says this, exceptpediatricians who like to claim that the specific age is 6 weeks, or 6 months,or 1 year.  Many physicians have toldtheir patients’ mothers that breast milk abruptly ceases to have anynutritional value after a certain length of time post-partum.  Many pediatricians and others report that theAmerican Academy of Pediatrics recommendation isto “breastfeed for a year.”  In reality,one year is the AAP’s minimum forweaning, while the World Health Organization and the American Academyof Family Physicians place the minimumat two years.  My research suggests ahypothetical range of 2.5 to 7.0 years – a very wide range of ages indeed.  I don’t know anyone who has ever claimed 2 years, 2.5 years, 4 years, 5 years,or 7 years, as Hinde states.  I don’tknow anyone who has ever claimed there is one specific optimal age for allmother-child pairs.  No one.

What she writes: “Firstof all, weaning is not an event, it is aprocess, so it can’t happen AT a time.”

What the realityis:  The term “weaning” meansdifferent things to different people.  Someresearchers are sloppy and don’t define their terms at all, leaving the readerto try to guess.  Some researchers definetheir terms and then aren’t consistent in using them as they just definedthem.  Some researchers define “weaning”as a process – Margaret Mead did.  Andsome researchers, including me, are very careful to define “weaning” as “theend of any breastfeeding.”  When weaningclearly is defined this way, weaning isan event.  When mothers talk about weaning, they arealmost always talking about the end of breastfeeding.  When asked “How old was your baby when theywere weaned?” they don’t respond “Well, she began solids at 4 months and nurseduntil 18 months.” Or “He began solids at 7.5 months and nursed until he was 4years and 3 months.”  No – they say “Sheweaned when she was 18 months old,” “He weaned at a little over 4 years.”  The “meaning of weaning” is how you defineit.  Most mothers of older nurslings willknow very specifically how old their child was when they were weaned.  In my research on moms in the US whobreastfed longer than 3 years, the vast majority knew, often to the date, whenthe last breastfeeding session took place. Some kids wean once and then come back and nurse again for a while – oneof my kids weaned at age 3 the first time, and at age 4 the second time.  It’s true that you can continue tonurse/breastfeed beyond when you are lactating, and that during the last weeksand months of full-term breastfeeding there may not be a significant amount ofmilk transferred.  But we needdefinitions, and “weaning” is much of the research literature as well as formost of the lay public means the end of breastfeeding.

What she writes: “Turnsout, new research is demonstrating that tooth eruption schedules aren’t asmeaningful for making this inference as we once thought (Smith 2013). In partthis is because average tooth eruption patterns were linked to averages for“weaning age” at the species level, but that tells us little about thevariation WITHIN SPECIES… which can be substantial.” 

What the realityis:  I am not aware of anyoneclaiming that there should be a link between an individual’s time of eruption of their first permanent teeth andthat individual’s age atweaning.  No one says this.  Another straw man.  In my original paper using nonhuman primatesas a source of information about how long humans would nurse if we didn’t screwit up with cultural biases and beliefs, I pointed out that Smith’s early workshowed a general relationship between age at weaning and eruption of the firstpermanent teeth in 21 primate species. In humans, eruption of the first permanent molar happens at 5.5 to 6.0years of age.  This gives us one clue asto what might be one indicator of a natural age of weaning for modern humans asa species.  No one has ever claimed thatthis relationship will hold true at the individual level, or that there is novariation in these variables, because both of these life history variables –age at weaning and age at first molar eruption – occur as ranges ofvariation.  We are comparing average toaverages.  If humans are like the otherprimates (other than chimpanzees, who have early first permanent molareruption), and the average age for eruption of the first permanent molars inmodern humans is 5.5-6.0 years, and if age at weaning should generally agreewith that, as it seems to do for many mammalian species, including manyprimates, then the average age of weaning for humans would also be 5.5-6.0years based on this ONE INDICATOR.  Not“all children will wean at 5.5 to 6.0 years” or “all children should be nurseduntil they are 5.5-6.0 years” – merely that the average in a human populationnot yet influenced by contrary cultural beliefs would probably be close to thisage, based on this ONE INDICATOR.  Thereare other indicators that are down at 2.5-3.0 years of age, and others at 4.5years, based on other life history variables, and all with their own ranges ofvariation!

Sidenote: I had a discussion with Dr. Hinde several yearsago about the fact that it had been known for years that chimpanzee’s did notfit the general rule of “age at weaning = age at first permanent molareruption” after she tried to argue that “new” data based on photos of yawningchimpanzees showed this lack of connection. Back in the mid-1990s, this was already in the published primate literatureand I cited this anomaly in several of my papers.

What she writes:(with respect to parent-offspring conflict). “This is why I find the AAP recommendation of “for as long as ismutually desired by the mother and baby” suboptimal, since parent-offspringconflict theory tells us that adaptive optima for mothers and offspring areexpected to differ.”

What the realityis:  There is nothing – “Nothing,Lebowski” – in the AAP recommendations that would lead one to think they areimplying that mother and child would agree on the time to stop breastfeeding.  When they say “for as long as is mutuallydesired by mother and infant” they are saying “as long as both parties to therelationship want to continue.”  It is arelationship – a close, physical relationship – between two people.  If the child no longer wants to breastfeed,then the relationship ends.  If themother no longer wants to breastfeed, then the relationship ends.  Sometimes the child weans before the mother reallywanted them to.  Sometimes the motherweans the child before the child really wanted to stop – and believe me, a3-4-5-6 year old can express some pretty cogent verbal arguments as to why theyshould still be allowed to nurse.  Theydon’t need to resort to “weaning tantrums” of the kind Jane Goodall hasreported for chimpanzees.  The AAP issimply saying that as long as both mother and child want to continuebreastfeeding, it’s absolutely fine to do so. [Side-note: Think of it like sex between consenting adults: if eitherpartner doesn’t want to have sex, then the other partner shouldn’t impose theirwishes.  But saying that both partnersshould feel free to have sex if they both want to, in no way implies that bothof them will always want sex at the same time. As every adult know.]

What she writes:“The gene expression that controls the production of lactase shuts down duringdevelopment as infants transition into juveniles.  But many humans have “lactase persistencegenes” that express well into adulthood. These genes have been favored by acultural context of dairying. Individuals who continued to express lactasepost-weaning living in populations that had cows, goats, camels, mares, andsheep were able to digest animal milks gaining protein and fat in their diet.This complex interplay between the human genome and cultural practices is knownas gene-culture coevolution. This complicates the inferences we can make aboutthe duration of breastfeeding and weaning times. Selective favoring of lactasepersistence may have been driven by animal herding (pastoralism), and as a byproductfacilitated very prolonged breastfeeding in some populations.”

What the realityis:  The terms “infancy” and“juvenile” are defined by zoologists based on dental eruption.  Infancy is birth until the eruption of thefirst permanent teeth.  The juvenilestage begins with the eruption of the first permanent teeth and continues untilthe eruption of the last permanent tooth. For humans, the transition from infancy to the juvenile stage begins at5.5 to 6.0 years.  The juvenile stagelasts until the late teens/early 20s.  Soyes, the variant of the lactase gene that shuts down in most of the world’spopulation in childhood does not allow adults to digest dairy products withoutunfortunate symptoms (burping, bloating, flatulence).  As for when this gene stops producing lactasein various populations, the research says 2 to 10 years.  Not surprising.  There is, no doubt, much population-level andindividual-level variation is when and how this gene stops producing lactase –is it an on/off switch, or a rheostat? Is the gene’s activity affected by whether or not human milk is aconstituent of a child’s diet, such that in a population where all adults arelactose intolerant, a child who is still nursing at age 5 will still beproducing lactase, while a child who was wean at 1 year is no longer producinglactase by age 2?  It’s an interestingresearch question – someone should do some research.

            However,the evidence does not at all support Hinde’s claim that nursing until the ageof 5 or 6 is the result of the coevolution of culture and biology in dairyingpopulations.  Indeed, many of the groupswith reported typically long durations of breastfeeding are not dairyingpopulations (and have never consumed milk) and therefore have not been selectedfor lactase persistence.  Breastfeedinguntil 5-6-7+ years in humans is not at all related to whether or not theculture has domesticated animals that they milk, and whether or not the adultsconsume nonhuman animal milks.  I am notaware of any anecdotal reports, let alone research, reporting cases of a childwho started having trouble digesting his own mother’s milk as he got olderbecause his lactase gene shut down.

What she writes:  “MYTH: We totes know the systematiceffects of very prolonged breastfeeding.”

What the realityis:  Sigh.  Yet another straw man argument.  NO ONE EVER CLAIMS THIS!!  As I have written in all of my scholarlypapers on this issue, and as I have concluded at the end of each of thehundreds (nay, thousands) of conference presentation I have done on this topic– there has been NO research on the comparative outcomes for children breastfedfor various lengths of time beyond two years. There have been a few studies that included a category of “18-24+ months”– but there have never been any studies showing what, if any, difference thereis in health outcomes, cognitive outcomes, emotional outcomes, etc. forchildren who nursed for only 3 years versus those who nursed for 5 versus thosewho nursed for 7.  Again, an interestingresearch question, and definitely one worth exploring, for lots ofreasons. 

            Theresearch that has been done to date shows clearly that the longer youbreastfeed, up to the study limits of 2 years, the better all the outcomes arefor mother and child.  Like an oil well, thebenefits decline over time, such that nursing for an extra month early on (age2 vs. 3 months) is going to be more significant than nursing for an extra monthat age 5 years (60 vs. 61 months).  Thereis no reason to expect that the benefits shut off abruptly at one year of age –as some pediatricians like to claim – nor is there any evidence to claim thatthe benefits are significant when a child is nursed 6 years rather than 5years.  This lack of research evidence isirrelevant to the point under discussion.

What she writes: “Theinformation of very prolonged breastfeeding of 5+ years comes from rareself-selected cases, an extreme tail end of a continuous distribution ofweaning ages.”

What the realityis:  Indeed, information about“normal durations of breastfeeding that last up to 6 or 7 years” represents theextreme tail end of a distribution.  Butnursing to 5+ years is not “rare” – not now, not ever.  There are lots of children – thousands andthousands – around the world who are nursing beyond the age of 3, with hundredsand hundreds nursing beyond the age of 5, and quite a few – though no onereally knows – nursing beyond 6 and 7. 

In my 2004 paper in Clinical Obstetrics and Gynecology, alsotitled “When to Wean” by the way, and available here on line for free: http://kathydettwyler.weebly.com/uploads/3/0/9/1/30918011/when_to_wean_clin_obstetrics_2004.pdfI report on a study I conducted in the mid-1990s on women in the US whobreastfed longer than 3 years.  I endedup with 1,280 mother-child pairs.  Therange of weaning ages was 3 to 9.17 years. Of the whole sample of 1,280, close to half had weaned by age 4years.  The average age of weaning forthe sample was 4.24 years, with a median of 4 years, a mode of 3.5 years, and astandard deviation of 1.08 years.  In theyears since I did this research, breastfeeding has become more common in theUS, more mothers are nursing longer (according to the CDC statistics), andwomen are being more vocal and open about how long they nursed their children,in part due to the support now available via the interwebs and celebrity momslike Dr. Mayim Bialik (http://www.mayimbialik.net/beyondthesling/).  Nursing until 5+ years of age may be somewhatinvisible or cloaked in Western cultures, but it isn’t all that rare.

What she writes:  “MYTH: The effects of breastfeeding arethe same for all moms & infants in all places always.”

What the realityis:  A “myth” is something that iscommonly believed to be true, even though it isn’t true.  Here we have yet another straw man.  I don’t know anyone who believes that “theeffects of breastfeeding are the same for all moms & infants in all placesalways.”  Not any researchers, not anyphysicians, not any mothers.  Noone.  NO. ONE.

What she writes: “MYTH:Moms have all the options.”

What the realityis:  Please see the answer to theprior question.  No one believesthis.  No one.  NO. ONE. As many of the very same people who are the most outspoken breastfeedingadvocates are the VERY SAME PEOPLE who are agitating for longer/bettermaternity leaves, on-site child care, flexible work schedules, laws to protectmothers breastfeeding in public, educational programs for partners and otherfamily members and employers, etc. etc. etc. etc.  If we “wait until the world has changed” andall these breastfeeding supports are in place before we start telling women thetruth about the consequences of their infant feeding decisions, we will neverhave a breastfeeding-friendly society. Readers are encouraged to look at James Akre’s brilliant book on thistopic from 2006.  Akre was the head ofInfant Nutrition for the World Health Organization for many many years. http://www.amazon.com/The-Problem-Breastfeeding-Personal-Reflection/dp/0977226840

What she writes:“We owe mothers better support and better options, including better formulasthat include more bioactive features of breast milk.”

What the realityis:  Indeed we do, and breastfeedingadvocates have been saying this for as long as I’ve been involved in the field– since 1979.  In fact, I state itexplicitly in my 1995 chapter “Beauty and the Breast” and in my 1998 SkompLecture “Evolutionary Medicine and Breastfeeding: Implications for Research andPediatric Advice.”  Both are availablefor free on my website at www.kathydettwyler.weebly.org

What she writes:  “Words have power. Words chastise, wordsshame, words bolster, and words buffer. So what do we do, as clinicians, asbiologists, as friends, when a single statement about breastfeeding, pro orcon, exerts each of those outcomes depending on the person reading and hearingthem?”

What the reality is:  Indeed, words have power.  Words can be outright lies.  Words can mislead people.  Words can be used to try to make women feelbetter by denying the reality of how the world works.  “Breastfeeding doesn’t matter, don’t worry ifyou have to stop when you go back to work.” Versus “Breastfeeding really doesmatter.  It’s a shame that your employerwon’t accommodate you.  You should beangry about this.  Let’s do somethingabout it.”  I have an entire presentationI have given at many many breastfeeding/lactation conferences on this wholetopic of whether telling mothers the truth is wrong/immoral if it makes themfeel guilty.  I side with truth.

What she writes:  So proscriptive attitudes about what womenshould and shouldn’t do with their bodies can suck it.

What the realityis:  I agree 1000%.  Proscriptive attitudes about what womenshould and shouldn’t do with their bodies can suck it.  Realize that most of these proscriptiveattitudes being expressed are aimed at demonizing women who nurse their childrenfor longer than someone else thinks they should.  Not at women who bottle-feed, and not atwomen who “only” nurse for 1 year or for 2 years or for 3 years.  No one – leastof all me – is saying that women “should” or “must” nurse their children atall, let alone for any specific length of time. 

So please stop implying that I am.