S5.21 Past to present: Searching for evolutionary stories in ancient DNA
Hello, and welcome to Genetics Unzipped - the Genetics Society podcast, with me, Dr Kat Arney. In this episode we’re exploring what we can discover about our evolution from our DNA, and what evolutionary secrets might be contained in the ancient DNA of our ancestors.
Image: PLOS Biology
Svante Pääbo: searching for secrets in ancient DNA
Where did we come from? And how are we related to the ancient species that came before us? Asking questions like these is part of what makes us human. But, genetically speaking, what really does make us human?
Well, Swedish geneticist Svante Pääbo is helping us find out - and, as has recently been announced, his work has led to him winning the 2022 Nobel prize in physiology or medicine “for his discoveries concerning the genomes of extinct hominins and human evolution”, as the committee put it.
EPAS1: The mountain gene
Life is tough on the roof of the world. The lofty heights of the Himalayan mountains, more than four kilometres up, present a breathless environment with around 40% less oxygen than at sea level - conditions that would quickly sicken or even kill most of us.
But some hardy humans not only survive there, but they thrive. Tibetans have lived in the thin mountain air for more than 6,000 years thanks to a gene variant they originally inherited from the Denisovans - the elusive human species first identified by Svante Pääbo and his team from a sample in the Altai mountains around 1500 miles north of the Himalayas. The thin air has favoured the persistence of one particular version of a gene called EPAS1, which allows these mountain-dwellers to get along just fine despite the shortage of oxygen.
My milkshake brings all the genes to the yard
While it might not be as dramatic a superpower as being able to live four kilometres up a freezing mountain, the ability of many humans to drink milk in adulthood is certainly handy.
Most animals can drink milk in infancy, but as they grow the lactase gene that digests lactose, the sugar found in milk, gets switched off. After this point, drinking milk results in a lot of stomach discomfort, diarrhoea, wind and general gastric unpleasantness. But around a third of the global population - especially those of European ancestry like me - have a genetic variation that allows the lactase gene to stay switched on indefinitely, known as lactase persistence, allowing us to chug the white stuff without a problem.
That’s all for now. Next time we’re taking a trip to the little shop of genetic horrors, looking at the evolution of carnivorous plants.
For more information about this podcast including show notes, transcripts, links, references, music credits and everything else head over to geneticsunzipped.com You can find us on Twitter @geneticsunzip and please do take a moment to leave us a rating in the Spotify app or review us on Apple podcasts - it really makes a difference and helps more people discover the show.
This episode of Genetics Unzipped was written and presented by me, Kat Arney. With additional research and scripting by Eleanor Bird. It is produced by First Create the Media for The Genetics Society - one of the oldest learned societies dedicated to promoting research, training, teaching and public engagement in all areas of genetics. You can find out more and apply to join at genetics.org.uk. Our theme music was composed by Dan Pollard, and the logo was designed by James Mayall, and audio production was by Sally Le Page. Thanks for listening, and until next time, goodbye.
References:
https://www.theguardian.com/science/2022/oct/03/nobel-prize-physiology-medicine-svante-paabo
https://www.nobelprize.org/prizes/medicine/2022/press-release/
https://www.newscientist.com/article/dn25835-tibetan-altitude-gene-came-from-extinct-human-species/
https://www.science.org/content/article/tibetans-inherited-high-altitude-gene-ancient-human
https://www.science.org/content/article/genome-brings-ancient-girl-life
https://academic.oup.com/mbe/article/37/9/2616/5834723?login=false
https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1008420
https://www.nytimes.com/2022/07/27/science/early-europeans-milk-tolerance.html
https://media.nature.com/original/magazine-assets/d41586-022-02041-y/d41586-022-02041-y.pdf
https://www.washingtonpost.com/health/2022/07/28/lactose-intolerant-europe-study-milk/
