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Dairy cows

Dairy cows.

Early African dairy farming, seabird migrations

31 July 2012

This week in the Planet Earth Podcast: how dairy farming in Africa 7000 years ago led to the speedy evolution of the gene that lets us digest milk; and how climate change could be having a detrimental effect on seabirds and fish in the Southern Ocean.

Scientists recently found the first direct evidence that prehistoric people in the Sahara used cattle for their milk as long as 7000 years ago. But rather than drinking the raw milk, it seems these early pastoralists used it to produce butter, cheese and yoghurt.

This may well have been because their guts hadn't yet evolved the enzyme necessary to digest a specific type of sugar found in milk called lactose. This was to come later, but the speed at which this evolution took place is remarkable. Richard Hollingham talks to Julie Dunne from the University of Bristol to find out more.

Next, Sue Nelson goes to the University of Glasgow to meet James Grecian, and finds out how changes in ocean temperature as a result of climate change could be affecting the migration patterns of seabirds.


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The Planet Earth podcast - 'Early African dairy farming, seabird migrations'.

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Finally, why trees colonising open tundra as the climate warms could cause Arctic soils to release vast amounts of stored carbon into the atmosphere. And what Cornish peat bogs reveal about the history of tin exploitation in the ancient world.

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Your comments

The headline for one of the topics was "How dairy farming in Africa 7000 years ago led to the speedy evolution of the gene that lets us digest milk". A quibble with the way it was expressed: All humans have a gene that digests lactose - but it turns off after about 5 years of age. I suggest that what changed in our DNA was not the lactase gene itself, but the regulatory pathways that control expression of the gene in children and adults.

evan_au, Sydney, Australia
Wednesday, 15 August 2012 - 12:44

Thanks for the correction Evan!

Tom Marshall, Planet Earth Online
Wednesday, 15 August 2012 - 13:30


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