Monday, January 27, 2014

Should Humans Drink Cow’s Milk?

This strongly suggests that it would be helpful to find a way to bring the enzymes into the gut of those who are lactose intolerant.  Otherwise milk products are a valuable food source.  Controversy on calcium is also misplaced only because the industry chose to connect the dots in a way that suited their marketing.

Otherwise, the dairy economy literally populated the forestlands of Europe.  A burned off clearing became pasture and easily remained pasture with modest effort.  These later became cropping fields.

A small herd provided real food security for a family and it was naturally conserved.  In time game meat was supplemented by semi wild pigs and chickens of course.  This all took place in a biome where plant foods were generally problematic, taking millennia to establish properly.

Should Humans Drink Cow’s Milk? New Study of Neolithic Farmers May Have the Answer


Many would remember the days when a milk trolley would be rolled out during morning recess at school and all the children would come running for their daily glass of milk, or the TV images of energetic children racing around the playground with the message to drink milk for healthy bones. However, new research has questioned whether drinking cow’s milk is actually good for us at all. The answer to this question may lie in a new study of our ancient Neolithic ancestors who first began the practice of dairy-related animal husbandry.

A multidisciplinary team of scientists from an EU-funded initiative, which began in 2009, examined the role played by milk, cheese, and yogurt in the early colonization of Europe and found that until 8,000 years ago, humans were only able to digest lactose, a form of sugar present in milk, during childhood and that as adults they lost the ability to produce endogenous lactase, the enzyme required to break down lactose.

However, shortly before the first farmers settled in Europe, a genetic mutation occurred in humans that resulted in the ability to produce lactase throughout their lives. Increasing numbers of adults in Central and Northern Europe were since been able to digest milk.

Just 5,000 years ago, lactase persistence was almost non-existent among the population but researchers believe that extensive positive selection and recurrent waves of migration were responsible for this development.

"To appreciate the significance of our findings, it is important to realize that a major proportion of present-day central and northern Europeans descend from just a small group of Neolithic farmers who happened to be able to digest fresh milk, even after weaning," explained Anthropologist Professor Joachim Burger of Johannes Gutenberg University Mainz (JGU).  This reveals that far from being normal, the ability to digest milk is only the result of a strange genetic adaption.

[ This genetic adaptation just happened to allow actual cattle husbandry and the populating of Europe. ]

Scientists point out, however, that 60% of modern-day people still lack the enzyme for breaking down lactose and just don’t know it, meaning that they experience a wide range of digestive and allergy problems which they have never had attributed to their milk-drinking.

Another argument that has been recently been debunked is that drinking cow’s milk increases bone strength and prevent osteoporosis. In fact, the skeletons of our Palaeolithic ancestors, who did not drink milk, reflect great strength and muscularity and a total absence of advanced osteoporosis, possibly due to the fact that research has shown we can get as much calcium as we need from grains and vegetables alone.

Of all the mammals on earth, human beings are the only ones who continue to drink milk beyond babyhood. Whether this should be the case or not is now in doubt.

Should Humans Drink Cow’s Milk? Part 2 - Digesting Milk in Ethiopia


Yesterday we reported on a new study of our ancient Neolithic ancestors who first began the practice of dairy-related animal husbandry and discussed the implications this may have with regards to the controversial questions – should human’s drink cow’s milk?  Now a second study has just been published in The American Journal of Human Genetics tracing the origins of the ability to digest milk in Ethiopia. A genetic phenomenon, called ‘soft selective sweep’, which allows for the selection of multiple genetic mutations that all lead to a similar outcome - the ability to digest milk - has been characterised for the first time in humans.  The study demonstrated that individuals from the Eastern African population have adapted to be able to digest milk, but via different mutations in their genetic material. We need lactase when we are babies to digest our mother's milk, so in babies large amounts of lactase enzyme are expressed by our genes. When we are older we no longer rely on our mother's milk for essential nutrients, so in most humans manufacture of the lactase enzyme stops through de-activation of the corresponding gene. However, subtle mutations in the regulatory region of the gene in some individuals cause lactase to carry on being expressed into adulthood. "Our genetic make-up determines our ability to digest milk into adulthood. Just over a third of the global population have inherited genes that allow us to make lactase, the enzyme that digests milk, as adults,” said Professor Dallas Swallow, from the Department of Genetics, Evolution and Environment. "This study shows that several different genetic changes that allow our bodies to make lactase have emerged independently. Changes to our lifestyle over the past 10,000 years -- including diet, altitude acclimatisation and infectious disease resistance -- will likely have caused many genetic adaptations of this kind,” said Swallow. Only in the last 5,000 to 10,000 years have humans started drinking the milk of other animals, following advances in our ability to herd animals. In times of plenty, being able to drink the milk of other animals would not have given a particular advantage to those with lactase persistence. However, in situations where food sources became scarce, individuals capable of producing lactase as adults would be able to drink the milk of their animals, increasing their chances of survival. Ethiopia has been subject to frequent droughts that contribute to famine. Individuals who can digest milk are more likely to increase their chance of survival under these conditions. – 

No comments: