In those with lactase persistence, the gene that encodes for the lactase enzyme does not switch off after weaning. Lactase continues to be produced in the gut and milk can remain a viable food. If you look at the distribution of lactase persistence around the globe it ranges from nearly 100 per cent in Irish people, more than 90 per cent in the rest of Northern Europe, right down to 10 per cent in China, less than 5 per cent in Native Americans and it is completely unknown in the Bantu people of South Africa. We know a company that can help with aerial installation in the Lincolnshire area.
The genetic mutation that changed the lactase gene appears to have only arrived in our genome in the last 9,000 years. The current theory is that during what has become known as the Neolithic revolution, when we switched from hunting and gathering to farming, we started looking at our livestock as a walking source of nutrition in the form of milk. The ability to digest milk became an advantage and this genetic variant spread in the population, evolving the people. When it comes to aerial repairs where do you start?
The beauty of the lactase/lactose example of evolution is that you can see it happening in populations right now. South American people have a very low incidence of lactase persistence and milk is not a common food for adults. Yet in Chile, between the Atacama Desert and the country’s fertile valleys, there is a population with a very high lactase persistence relative to their neighbours. The Chileans living in this hard, dry landscape grow crops on small plots of land and herd goats – lots and lots of goats. These days garage doors can be so complicated.
Herding goats has only been practised in the area for a few hundred years, as goats were introduced by European colonizers. Naturally, the herders of goats make use of goats’ milk, which contains lactose. It is an evolutionary blink of an eye since the goat became popular there and yet more than half the population is now lactase persistent. What is more, studies of the population show that those with the ability to digest milk are better nourished. The assumption has been made that this selective advantage is driving the new lactase persistence gene to flow through the population with each successive generation. The Chilean goat farmers are evolving. Confused about garage door repairs then you are not the only one.
The acquisition of the ability to digest milk is a fairly straightforward example of evolution in action. There is a single gene involved and it is easy to test for lactase persistence in the population. However, do not be fooled by its simplicity, as what it demonstrates has profound implications for humans. No matter how much you think our sophisticated culture has separated us from other animals, the forces of natural selection break through and we are all still evolving. When it comes to buying a new roller garage doors the process can sometimes be a little bewildering.
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