For most of human history, milk has essentially been a poison to adults. Though children, like the young of most animals, have always been able to consume dairy. Almost all young animals are able to break down the lactose with the production of the lactase enzyme (That is lactase not lactose, lactose is a sugar in the milk and lactase is the protein that we make to break down the sugar). However most adults of the world then stop producing this lactase and as a result are unable to consume dairy without unfortunate results. But humans were never built to consume dairy anyway, at least not really.
The world was (and in many places still is) a place full of lactose intolerant adults. Though the children of the world are often far luckier. An injustice of nature humans apparently saw fit to rectify, well at least some humans. A brave collection of humans ready to overcome their bodies repulsion to what is essentially calf-growth formula, by consuming this ancient toxin.
Now. This wasn’t going to kill them. But the reactions to dairy for those with a lactose intolerance, according to WebMD are the following:
The tales of history are so often those of Kings and Queens, of great warriors and leaders, but some commendation must be given to the bloated, cramp-ridden, gurgling, puking individuals who’s sacrifice allowed for the present-day consumption of dairy (for some individuals anyway).
Okay, it may not have happened exactly like this. It was more likely an evolutionary mutation in some individuals that was so beneficial it meant the dairy consuming populations lived longer and then… bred more? Milk drinkers were just sexier? This has been a strange phenomenon in our evolutionary history that has been the subject of much debate in many academic circles. I mean, dairy is a good way to have a protein-rich diet (something common in India for example), but it’s hard to say that the humans who survived and spread this mutation were those who drank milk, and all those water drinking humans….just died out? Moved?
A current popular theory is the following:
Step One: Farming
The practice of farming takes over around 11,000 years ago, spreading from the Fertile Crescent into Europe. It then appears it was these farmers who discovered a way to consume dairy. They appear to have figured out how to reduce lactose in dairy products to more tolerable levels by fermenting milk to make cheese and yoghurt. So it was still a toxin to humans and there were still likely side-effects, but that won’t stop the Europeans eating cheese.
When did this occur? Well the Lactase Persistence in the early Cultural History Europe group (LeCHE) ran chemical tests on ancient pottery and analysed from residue what types of fat were absorbed during the cooking process in these pots. From this they found clear evidence Europeans were producing cheese to supplement their diets between 6,800 and 7,400 years ago. It appears to have been the practise of the European farmers then.
Step Two: Genetic Mutation
Thousands of years pass and a genetic mutation spreads through Europe, a mutation that allows people to drink milk by producing lactase. This trait is from the LP allele and this allele appears to have had a significant selective advantage (and not that milk drinkers are just sexier). A 2004 study showed that those with the mutation produced up to 19% more fertile offspring. So it appears that when farmer populations moved into Europe, those with the LP allele had more children and therefore the mutation spread.
(Image Reference: Curry 2013)
This would explain why it’s a minority of people in Europe who are lactose intolerant compared to the rest of the world. In fact the further into Europe from the Fertile Crescent area you get it appears a greater proportion of people tolerant to lactose. Also then, if you can consume milk then you can probably trace your ancestry back to Europe. This would also explain why the U.S.A also has a smaller amount of lactose intolerant individuals, due to the large number of Europeans who moved there.
Extra Extra… Dairy Consumption by Country
In Europe our dairy consumption, like our meat consumption (see related post) is incredibly high. Some might say unnaturally so…
Although it is hard to get comprehensive data on worldwide dairy consumption, the Food and Agriculture Organization of the UN once collected such information. I think it has since stopped (probably hard to justify collecting milk-consumption figures during an economic downturn), however it did collect this information up until 2007.
The UK dairy consumption per capita in 2007 was….241.47kg.
To put this in perspective, the consumption in Russia was 177.49kg per capita. While in Egypt it was 61.81kg and finally in China it was a minuscule 28.7kg. The incredible consumption of dairy in Europe and the U.S then is arguably neither natural nor necessary, and given the horrible conditions of nearly all dairy cows on industrialised farms, maybe there is some room for cutting back….? Food for thought.
Bersaglieri, T., Sabeti, P., Patterson, N., Vanderploeg, T., Schaffner, S., Drake, J., Rhodes, M., Reich, D. and Hirschhorn, J. (2004). Genetic Signatures of Strong Recent Positive Selection at the Lactase Gene. The American Journal of Human Genetics, 74(6), pp.1111-1120.
Curry, A. (2013). Archaeology: The milk revolution. Nature, 500(7460), pp.20-22.
Faostat.fao.org. (2016). FAOSTAT. [online] Available at: http://faostat.fao.org/site/610/DesktopDefault.aspx?PageID=610#ancor [Accessed 6 May 2016].