Harvard Thinks Big: "Why Mammals Suck"
On January 31, 2013 I was invited to give a mini-talk to Harvard undergraduates about a "Big Idea." Although I wasn't able to talk specifically about my own research, I was able to highlight why milk is awesome, why everyone should care, and how that caring should translate in the community. I have embedded the 12 minute video and the text (minus the flubs) that goes along with it below.
click video to play
“Why Mammals Suck”
Imagine a magic potion. This potion includes all of your calories and water. It has fatty acids to build your brain, glucose to fuel it, amino acids to build muscles, minerals to build your bones. vitamins, immunofactors, hormones. The things you need at the times you need them. Oh, and one last thing, your mom makes it just for you. This magic potion, of course, is milk and is why mammals suck.
The synthesis of milk by mammary glands is the defining characteristic of our mammalian class- its where we get out name. Dobzhansky said “Nothing in biology makes sense except in the light of evolution.” And an evolutionary perspective is critical for understanding milk. Mothers that synthesized milk that best enabled infants to survive and thrive were most “successful” and favored by Darwinian natural selection. And they passed those genes onto their daughters who passed them on to their daughters as selection acted on each generation for the last 250 million years. Eventually giving rise to the diversity of mammals and their lactation strategies on every continent of the globe.
RAWR! (Two of these things are not like the others)
Although only mammals have mammary glands, in other areas of the animal kingdom one can find substances analogous to mammalian mother’s milk. Pigeons, discus fish, and bat flies- mothers & sometimes fathers, produce nutritious substances to nourish young that need this "milk" to survive. However these species are rare variants among birds, fish, and insects.
pretenders to the throne
MAMMALS SUCK WAY BETTER.
Unfortunately, the ubiquity of milk in our environment allows us to take it for granted. I can go to the store and buy dairy milk in vast quantities. Since the late 1800’s commercial infant formulas have been available. And so our collective perception of the specialness of mother’s milk is lost. And milk is so incredibly special.
Milk contains hundreds, likely thousands, of bioactive constituents. But… we don’t know exactly what all is in milk, how it all gets there, and what those constituents do when ingested by the infant...
FOR ANY MAMMAL, INCLUDING HUMANS
In preparation for this talk I searched for life science and biomedical research articles using milk related key terms in the database maintained by the National Institutes of Health. The devastating big picture is that there is relatively little research on mother’s milk.
Most of what we know about milk, lactation, and the mammary gland actually comes from dairy science, breast cancer research, and comparisons between breast-milk and formula. As a result the nuances of milk composition remain unknown. This is especially astonishing because eating a healthy diet are key messages coming from our doctors, teachers, parents, the news and the First Lady. Yet we don’t systematically know about the earliest food a human has evolved to consume!
And we need to know these things, because from what we know so far, milk is freaking amazing. Some of the major health crises facing the world today are prevented, reduced, or most effectively treated with breast-milk.
Over 1.5 Billion people are overweight including more than 40 million children under the age of five. Prospective studies and randomized trials have shown that breast-milk reduces the risk of developing obesity. Diarrheal Disease is the second leading cause of mortality under age 5 worldwide and special sugars in human breast milk protect against against diarrheal diseases by promoting a healthy gut microbiome. The incidence of pre-term birth is increasing and premature babies in neonatal intensive care units are healthiest when fed breast milk. In the last several months its been reported that breastmilk contains antiviral factors that kill HIV, and stem cells that can mature into cells from all three germ layers.
These discoveries have the potential to change medicine and improve human health. But only if we can take scientific results from the lab out into the real world. And this is where you come in.
Most of you will become parents, all of you will be health consumers, and tax payers. I trust that all of you are already voters. And so you have a serious stake in the issues at hand. And as you go forward, all of us, as a society, need to know one important thing:
WE ARE FAILING MOTHERS.
photo by Dorothea Lange
A majority of mothers intend to breast-feed but fail to meet their breast-feeding goals. There are a number of reasons for this, but many of them boil down to the simple fact that the challenges, difficulties, and barriers to breast-feeding are under-appreciated by mothers, their doctors, and the people around them.
Mothers can have trouble with infant latching, milk let-down, perceptions of milk supply, and pain. Just because lactation is “natural” and has deep evolutionary roots, doesn’t make it easy. You know what else is natural and evolved?
SEX.
...and we all start out being terrible at it.
Additionally, although mothers have received the message of the magic potion that is milk, the message has not informed policy to the same extent. We emphasize the importance of breast-feeding, but then handicap women from succeeding. Without the societal infrastructure needed- paid maternity leave, clean and safe breast-pumping stations and milk pumping breaks, mothers can’t maintain lactation. We need to do more to give mothers a diversity of healthy options.
And for women who don’t breast-feed, for whatever reason- economic realities, health conditions, cultural values- we owe it to them to make infant formulas better. We need to systematically know what is in milk, why it varies among mothers, and what those bioactive constituents do for the infants so that formulas can more closely approximate mother's milk.
Because when we fail mothers, we are not only failing mothers, we’re failing their infants. And we fail the people who love those mothers and infants- the fathers, the partners, the grandparents, the extended family and friends. Its not just a Sunday in May, every day should be mother’s day.
These are the real-world implications that motivate my research on mother’s milk. But milk is not my big idea- milk is not even an idea. Milk is one of nature’s wonderful accidents that became a incredible adaptation.
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Special thanks to Danielle Lemay for her "magic potion" metaphor, Kate Clancy, Lauren Milligan, Kathy West, and Alex Georgiev for the use of awesome photos.
Further reading:
Hassiotou et al. 2012 Stem Cell 30:2164–2174
Neville et al. 2012. Lactation and neonatal nutrition: defining and refining the critical questions. Journal of Mammary Gland Biology and Neoplasia. DOI: 10.1007/s10911-012-9261-5
Wahl et al. 2012 PLoS Pathogens 8(6): e1002732
Read more about the Comparative Lactation Lab
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