Once upon a time, all humans on Earth had brown eyes until a single person had a genetic mutation affecting the OCA2 gene, perhaps as recently as 6,000 to 10,000 years ago. The chance mutation impacted the production of melanin pigment in the iris, giving rise to lighter shades of eyes, from amber and hazel to green and blue.
The Evolution of Eye Colors
Despite the complexity of eye color genetics, trends can be seen across different regions of the world. Brown eyes remain the most common amongst modern-day humans, with variations occurring significantly from region to region. In the US, a 2014 survey by the American Academy of Ophthalmology revealed that 45 percent of the population have brown eyes, 27 percent have blue eyes, 18 percent have hazel eyes, 9 percent have green eyes, and the remaining 1 percent boast unique eye colors.
Global Insights
Research on eye color distribution around the world sheds light on interesting patterns. Studies indicate that while brown eyes dominate in Africa, South Asia, and East Asia, Europe and Central Asia display significant diversity. A 2019 study showcased a varied percentage of eye colors in countries such as Armenia, Iceland, Denmark, Great Britain, France, Georgia, Germany, Kazakhstan, Ukraine, and Uzbekistan.
The Mystery of Blue Eyes
Europe's unique prevalence of blue eyes has puzzled scientists, prompting various theories. The 'vitamin D hypothesis' suggests that light-colored skin, hair, and eyes helped prehistoric humans adapt to less sunlight in northern latitudes, while Neanderthal genes in Europeans are also considered. The complexity likely involves genetic drift, founder effects, and natural and sexual selection processes.
Contrary to myths, blue eyes are not facing extinction. As a recessive trait, both parents must carry the gene for blue eyes to pass it on. While some speculate about the disappearance of blue eyes, the genetic diversity ensures their presence in the human population for the foreseeable future.
In Conclusion
Just like red hair and other recessive traits, blue eyes continue to captivate. While the world showcases a beautiful diversity of eye colors, the legacy of blue eyes remains strong, adding to the rich tapestry of human genetics.