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The vast majority of human beings in history originated from Africa. The scientific evidence points to that continent as the place where homo sapiens evolved from before spreading throughout Europe and the rest of the world. That also means that the majority of people back then had dark skin tone and eye color.
However, the blue eyes genes soon evolved, and scientists confirm that they first arrived before light skin tone was ever common, highlighting the different stages that human appearances went through evolution.
Ancient DNA Reveals a Surprising Timeline
Scientists sequenced DNA from a 7,000-year-old skeleton found at La Braña in Spain and discovered that he had blue eyes despite having dark skin tone genes. These fossil remains are now called La Braña 1, signifying that human eye color changed long before skin did.
This challenges the notion that blue eyes evolved in Europe together with light skin genes. The presence of this fossil, along with a few others that were recently discovered, scientists now confirm that blue eyes likely came first before light skin was ever common.
Read more: IFL Science
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The Single Mutation Behind Blue Eyes
Researchers traced this appearance of blue eyes in humans to the HERC2/OCA2 gene region. The studies suggest that a mutation happened in this part of humans’ DNA that caused the blue eyes to appear about 6,000 to 10,000 years ago. This is also a sign of a single origin, which means that all blue-eyed people today likely came from a specific individual who mutated.
However, a new finding where a 17,000-year-old child fossil was discovered, who probably also had blue eyes and dark skin, takes this timeline even farther, suggesting that blue eyes might have manifested long before the old estimate.
Light Skin Evolved Later
Genes for light skin like SLC24A5 and SLC45A2 only appeared around 20,000–30,000 years ago; however, it would have taken a lot of time before a whole group of population had adapted them. Studies suggest that light skin in Europeans only occurred relatively recently, just about 3,000 years ago.
This means that the homo sapiens who migrated to Europe from Africa could have had dark skin but still passed on the trait to have blue eyes to their infants. However, that combination is now rare, as almost the entire population of blue-eyed people also has a lighter skin tone.
Read more: Wikipedia
Human Appearance Evolved in Stages
These findings suggest that human appearances evolved over time; we did not suddenly have a population of light-skinned and blue-eyed individuals, but rather a slow progression through genetic variations and adaptations until the two genes mixed up and became the dominant traits.
Our ancestors did not change overnight; each feature is a response to their environment, migrations, and genetic shifts, all for the survival and adaptation of the human race.
Author's Final Thoughts
The appearance of blue eyes before light skin shows our evolutionary process is not linear or a simple path, but rather one that is full of twists and turns. Each trait emerged on its own timeline, shaped by our desire to survive and pass on our genes to the next generation. To end, these genetic events remind us that humans are full of surprises and stories, even in our eyes.
References & Further Reading
Olalde, I., et al. (2014). Genome sequence of a 7,000-year-old Mesolithic European. Nature. https://doi.org/10.1038/nature12960
Lazaridis, I., et al. (2014). Ancient human genomes suggest three ancestral populations for present-day Europeans. Nature. https://www.nature.com/articles/nature13673
Mathieson, I., et al. (2015). Genome-wide patterns of selection in 230 ancient Eurasians. Nature. https://pmc.ncbi.nlm.nih.gov/articles/PMC4918750/
Beleza, S., et al. (2012). The timing of pigmentation lightening in Europeans. PLOS Genetics. https://pmc.ncbi.nlm.nih.gov/articles/PMC3525146/
Günther, T., et al. (2018). Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation. Nature Communications. https://pmc.ncbi.nlm.nih.gov/articles/PMC5760011/
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