Explanations for population variation in adult milk digestion depend on evolutionary histories with...

11
Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage. So, it is essential to know what consumption practices were like in the past, especially among populations with high frequencies of lactase persistence. We do know that milk consumption becomes much more common in the late 19 th century in Europe and the United States, but why?

Transcript of Explanations for population variation in adult milk digestion depend on evolutionary histories with...

Page 1: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.

So, it is essential to know what consumption practices were like in the past, especially among populations with high frequencies of lactase persistence.

We do know that milk consumption becomes much more common in the late 19th century in Europe and the United States, but why?

Page 2: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Earliest domestication of dairy animals was ~8,000 years ago in the Middle East

Milk may have been one of the earliest uses for these animals, who were also used for other purposes

Cows (Bos taurus and Bos indicus) were important sources of milk in Europe and South Asia, respectively

Goats and sheep were more common in the Mediterranean

Lactase persistence co-evolved with milk usage in Europe, Africa, and South Asia.

© 2011 Taylor and Francis

Page 3: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Evidence from household budgets, rations for poorhouses, representations in art, culinary traditions

Probably not – more frequently used to produce cheese, butter, buttermilk. Whey used in porridge

Beer or wine more common as beverages for both adults and children

© 2011 Taylor and Francis

Page 4: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Coffee, tea, and chocolate, which were all products imported from European colonies, were often consumed with milk.

This reduced bitterness and gave rise to an increase in milk consumption in Europe in conjunction with these commodities.

These were often consumed by workers as a cheap stimulants and “hunger-killers” (See Sidney Mintz, Sweetness and Power)

© 2011 Taylor and Francis

Page 5: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

No domestic source of milk – had to purchase from the market

Concern over “putrefication” – i.e. traditional modes of fermentation of milk products

More women working in factories – in need of a breastmilk substitute for infants

Urban women lost their social network for wet nursing and cows milk became the wet-nurse substitute as well © 2011 Taylor and

Francis

Page 6: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Cows kept in close confinement outside of cities – spread of disease

Cows poorly nourished and fed “swill,” the remains of alcohol fermentation

No means to keep milk cold while it was transported to urban consumers

Milk contaminated with pathogens – contributed to infant and child mortality

© 2011 Taylor and Francis

Page 7: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

© 2011 Taylor and Francis

A ghoulish figure selling swill milk to a mother and her sickly child in New York City(Source: Harpers Weekly (1878)).

Correlation of trends in child deaths from diarrheal disease and spread of pasteurization in Massachusetts (Source: Drawn from data in Crumbine and Tobey (1929)).

Page 8: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

Louis Pasteur – heating destroys microbes that induce fermentation or that cause disease.

Robert Koch – germ theory of disease (1882) Concerns about milk’s safety led to pasteurization of milk

supply to cities in late 19th- early 20th century Questions about milk as an appropriate food, especially

for children, were framed in terms of safety; it was assumed that milk drinking was the “natural” state of affairs

Ensuring a safe milk supply was seen as a way of solving some of the social problems of city life in the 19th century.

Refrigerated transport allowed broader distribution of pasteurized milk.

© 2011 Taylor and Francis

Page 9: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

With increased production of milk, need for larger market

Children (older than infants) became the target market for milk

National Dairy Council formed in 1915 to promote milk

Child health equated with milk drinking

Milk promoted as key to child growth© 2011 Taylor and Francis

Page 10: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

© 2011 Taylor and Francis

Milk promotion emphasizing milk’s value for child growth (Source: Ladies Home Journal (June 1904)).

U.S. Bureau of Education recommendations for schoolchildren (Source: Reaney (1922)).

Page 11: Explanations for population variation in adult milk digestion depend on evolutionary histories with dairying and milk usage.  So, it is essential to.

© 2011 Taylor and Francis

Trends in fluid milk and cheese consumption in the United States (Source: Drawnfrom data from United States Department of Agriculture (2008)).

•Milk consumption peaked during WWII and has been declining ever since and is well below levels from the early 20th century

•Cheese consumption has continued to climb

•Does this represent a return to pre-industrial forms of milk/dairy consumption?