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Can we be categorised by our DNA?

Updated Monday, 25th April 2022

“Race is just a social construct!” You may have heard experts say, but what does the science say? Can our DNA group us the way many imagine?

But those people look so different than us! How can scientists deny such a conspicuous difference?

If this debate sparks your interest, then this video is for you. Of course, you are not alone. For thousands of years, voyagers, explorers, chroniclers and anthropologists have travelled to far-away lands and noted the conspicuous differences in appearance between them and the people in these new lands.

PDF document Transcript 89.4KB

Ethnicities should not be thought of as distinct, discrete genetic groups that are far apart. We humans are rarely stagnant and isolated – we flow, spread, and mix. This genetic continuity means that the genetic landscape is actually formed of gradients, shaped by geographical features. For example, France and South Africa are far apart indeed, and the native people are also visually very distinct. But there is definite continuity in geography and the people – Kenya, Ethiopia, Egypt, the Middle East, Turkey, Greece, Italy all form a geographical continuum and between France and South Africa, and the people of those countries also form a link in terms of their population history, genetics, and appearance. In between, geographical features such as the Sahara and the Mediterranean Sea have shaped the human history, but it could not keep them isolated.

In this animated video, we provide a simple analogy to explain this continuity. While we think of colours as distinct, and assign them different labels such as red, green and blue, we look at a colour palette to understand the continuity of colours, and the difficulty of assigning discrete labels.

In other words, we do not deny that the people of South Africa would on average have much darker skin compared to the people of France. But we want to point out that, if you go northwards, there is a continuous shift from darker to lighter skin colours. And if you don’t look at the people of those two countries in isolation, but at all the people of Europe, Middle East, and Africa together, you will see a great blend of skin colours, where it will be really difficult to draw a sharp boundary and split people into categories like “light” vs “dark” based on their skin colour. This is also illustrated in the video with the intuitive analogy of colours.

Finally, the same notion is discussed in the context of ethnic groups. Here the British Isles is a prime example, being the melting pot of many ethnicities over millennia, such as the Celts, Vikings, Romans, Angles, Saxons, Normans, and so on. We discuss how this intermixing has created gradients across the UK, and splitting people into groups for any purpose, such as for direct-to-consumer (DTC) ancestry estimation, is somewhat arbitrary. We also discuss how this history of migration and intermixing links the British people to their continental European neighbours – a person from Orkney might be genetically closer to an average Scandinavian than an average Briton, while a person from Northern Ireland might be genetically closer to an average Irish person than an average UK person. 

What this means is that political boundaries, which we often end up using, are not always appropriate either. In reality, all boundaries are arbitrary and artificial to an extent!

If you enjoyed this article you might be interested in looking at The Open University’s Open qualification.                             

 

References 

  • Bycroft, C., Fernandez-Rozadilla, C., Ruiz-Ponte, C. et al. (2019) ‘Patterns of genetic differentiation and the footprints of historical migrations in the Iberian Peninsula’, Nature Communications 10(551). Available at: https://doi.org/10.1038/s41467-018-08272-w 
  • Chacón-Duque, JC., Adhikari, K., Fuentes-Guajardo, M. et al. (2018) ‘Latin Americans show wide-spread Converso ancestry and imprint of local Native ancestry on physical appearance’, Nature Communications 9(5388). Available at: https://doi.org/10.1038/s41467-018-07748-z 
  • Gilbert, E., O’Reilly, S., Merrigan, M. et al. (2017) ‘The Irish DNA Atlas: Revealing Fine-Scale Population Structure and History within Ireland’, Scientific Reports 7(17199). Available at: https://doi.org/10.1038/s41598-017-17124-4 
  • IGSR: The International Genome Sample Resource (2021) The 1000 Genomes Project. Available at: https://www.internationalgenome.org/ (Accessed: 25 April 2022).
  • Leslie, S., Winney, B., Hellenthal, G. et al. (2015) ‘The fine-scale genetic structure of the British population’, Nature 519, pp. 309–314. Available at: https://doi.org/10.1038/nature14230
  • Randall, (2010) ‘Colour Survey results’ xkcd The blag of the webcomic, 3 May. Available at: https://blog.xkcd.com/2010/05/03/color-survey-results/ (Accessed: 25 April 2022).
 

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