The figure of 4.2 years from Lawrence is bogus.  I will paste in part of my
new book that dicusses this.  Please do NOT reprint this anywhere, though
you are welcome to cite the 2.8 year figure from my chapter "A Time to Wean".
>
>Excerpt from unpublished manuscript by Katherine A. Dettwyler (1997):
>
>A worldwide average age of weaning?
>
>       That pesky 4.2 year figure.  For many years, Ruth Lawrence has claimed in
her book Breastfeeding: A Guide for the Medical Profession, that there is a
worldwide average duration for breastfeeding.  She writes: "The average time
of complete cessation [of breastfeeding] worldwide is 4.2 years."  (Lawrence
1994:312).  This 4.2 year figure is widely cited by numerous groups,
including La Leche League members, lactation consultants, and parents.  It
turns up again and again on Internet forums, sometimes referenced to
Lawrence, sometimes just as "I heard somewhere that. . . ," or "Since the
worldwide average is 4.2 years. . ."
>       Lawrence does not provide any citation for this figure in her book, and
there are no ethnographic data to support the 4.2 years figure, neither for
the modern world, nor for any time in the near or distant past.  In addition
to the lack of ethnographic evidence, there are other problems with this
claim.  In order for 4.2 years to be the "true" average, there would have to
be many many societies that nursed their children for an average of more
than 4.2 years, in order to offset the many societies that nursed their
children for an average of less than 4.2 years -- to balance out and come up
with an average of 4.2. The ethnographic literature provides no
documentation for any society where the average age of weaning is as long as
five or six years, which would be necessary to balance out the many
societies with averages less than four years.  In the ethnographic
literature there are many references to societies where individual children
may be nursed that long, and even up to the age of 12 or 15 years, but the
average in those societies is still between two and four years.  There are
also ethnographic references to cultures (or sub- cultures,  in the United
States) where children are allowed to nurse as long as they like, and
individual children may nurse for 8-10 years, but again, the vast majority
of children in child-led weaning situations stop breastfeeding voluntarily
between three and four years of age, so the average for those societies
continues to be less than 4.2 years.
>       The ethnographic data.  In 1964, Ford published data on average age of
cessation of breastfeeding for 66 "traditional" cultures.  Ford's data came
from anthropological research by various anthropologists in 66 "traditional"
societies around the world, prior to 1945.  This means prior to the
widespread production and marketing of artificial infant formulas around the
world by multinational corporations.  From Ford's data, one can calculate an
average cessation of breastfeeding  age of about 2.8 years, with some
cultures having an average age much earlier, and some up in the 4 and 5 year
range.  From my discussion of this data, at least one researcher has now
begun to claim that the worldwide average age for the cessation of
breastfeeding is three years.
>       Problems with calculating such an average.  However, even this admittedly
more reasonable claim is bogus.   What would a world-wide average really
mean?  How would one even calculate such a thing as a single, worldwide,
average age for cessation of breastfeeding?  Take each child's age at
weaning and add them up and divide them by the number of children?   Do you
add together and then divide by all the published figures for each
"culture," so that my study of 116 Bambara children from a peri-urban
community counts as one data point, and someone else's study of a rural
Bambara village counts as another data point?  Or do you average the two
averages, and report only one figure for each culture?  Or do you take an
average age at weaning for each country, based on all the studies done on
various ethnic groups within that geopolitical entity?  In that case, the
millions of children in China count for one data point, the same as the
thousands in Mali.
>       It might be more interesting to divide cultures up into types based on
subsistence mode and/or political organization, such as hunting and
gathering bands, subsistence horticulturalists at the tribe level,
fisher-folk, state-level peasant agriculturalists, industrial, and
post-industrial.  There would be many more data points for tribal societies,
as there are many more distinct tribal cultures than there are industrial or
post-industrial.  Another issue would be the time-frame of when the data
were collected.  Ford's data came from prior to the 1950s.  Duration of
breastfeeding has been dropping in many "traditional" societies as they
become exposed to Western cultures, and as artificial infant formulas are
promoted heavily in their part of the world.  For example, in Mali in the
1980s it was common for children who lived near the capitol city to stop
breastfeeding around two years of age, although the "traditional" duration
of breastfeeding out in the rural areas had been three to four years, or
longer, for as far back as the elderly people (born and raised in rural
areas) could remember, and was still three to four years in some remote
regions of the country.  You can't really enter into the calculations data
for some remote New Guinea tribe collected in the 1920s, and count it the
same as the data for a peri-urban community in Mali in the early 1980s.
>       A U.S. average?  What would be the average age for cessation of
breastfeeding in the current United States?  In many parts of the country,
almost half of the children born are never put to the breast, thus their
"duration of breastfeeding" is zero.  Do we include them in our
calculations?  If so, the average duration of breastfeeding will be
extremely low.  If we limit our calculations only to those children who are
breastfed at least once, problems still abound.  In the extremely
breastfeeding-unfriendly culture of the United States, many hospital
policies and practices are inimical to breastfeeding--mothers are given
drugs during labor that cross the placenta and affect the baby's ability to
latch-on properly and coordinate their sucking and swallowing; mothers and
babies are routinely separated after birth, often for many hours; many
babies are given bottles of artificial infant formula, sugar water, and
pacifiers in the hospital nursery; mothers are advised to breastfeed on a
strict schedule, for a certain number of minutes per side; and mothers are
routinely sent home with free samples of artificial infant formula.  All of
these practices are known to interfere with the establishment of successful
breastfeeding.  Add to this the fact that many women have never seen anyone
breastfeed, have little support from family and friends, and have no access
to health care professionals who are knowledgeable about breastfeeding, and
it is not surprising that many women "give up" within the first few days or
weeks of their child's life.
>       If it takes about six weeks for lactation to become well-established and
for mothers and children to settle into a successful breastfeeding
relationship, then perhaps we should not count in our "average duration"
calculations any children who are breastfed for less than six to eight
weeks.  Even where breastfeeding is going well, many women switch their
children over to formula in bottles when they return to work at six weeks
post-partum.  Are these children "weaned"?  Do we eliminate them?  If we
only count in our calculations children who are nursed beyond four weeks, to
capture those who were weaned when their mothers went back to work, then we
can perhaps say we have a fairly good idea of how long children are
routinely nursed at the breast in the United States.  But again, what would
this average age be, and what would it mean?  I suspect that a graph of the
distribution of age at cessation of breastfeeding for children in the United
States, counting only those who breastfed longer than four weeks, would be
heavily skewed to the right.  The peak (mode) would be less than 12 months,
the median only slightly higher than the mode, and the mean somewhat higher
still, due to the small but significant portion of children breastfed for
three, four, five, six, seven, eight, and even nine years of age.
>       It is much more meaningful, for each clearly defined population, to report
the range and the shape of the distribution, rather than just the mean.  My
own research suggests that the "natural" duration of breastfeeding among
human, speaking biologically/physiologically, would be somewhere between 2.5
years and 7.0 years, with 5-7 years being the most likely (see section *.*).
At the same time, the cross-cultural literature suggests that most children
stop breastfeeding by  themselves between three and five years if allowed to
nurse as long as they want.  To speak of a single, world-wide average age at
cessation of breastfeeding seems about as meaningful as speaking of a single
world-wide average height, or average age of menarche.  The 4.2 figure cited
by Ruth Lawrence is clearly not valid, regardless of how useful people have
found it for justifying extended breastfeeding.  The 2.8 year figure cited
in my work represents traditional societies before the mid-20th century.
>
Katherine A. Dettwyler, Ph.D.
Associate Professor of Anthropology and Nutrition
Texas A&M University