In our racially charged, and often divided society, skin color is still one of the most definable variations in the human species. While many narrow-minded orators (and even a prominent scientist) would have people believe that the color of their skin suggests they are somehow superior and that their epidermal shade came about through an act of divine providence, new evidence from an international team of scientists led by researchers at University College London (UCL) would propose otherwise.

Over 150 years ago, Darwin theorized that variations in skin color arose in humans through some natural selection mechanism and was tied to geographical location as well as sun exposure. It turns out, Darwin’s hypothesis wasn’t far off the mark as previous scientific work has uncovered a host of genes associated with skin pigmentation and UV exposure. Now, UCL geneticists, studying diverse Latin American populations, have identified new genetic variations associated with skin color. Findings from the study—published today in Nature Communications through an article titled “A GWAS in Latin Americans highlights the convergent evolution of lighter skin pigmentation in Eurasia”—showed that the variation of light skin among Eurasian people evolved independently from different genetic backgrounds.

The research team found five new associated regions involving skin, eye, and hair color. Genes affecting skin color in Europeans have been extensively studied, but here researchers identified an important variation in the gene MFSD12 seen uniquely in East Asians and Native Americans.

“The pigment melanin determines our hair, skin, and eye color. This gene MFSD12 influences how melanin is produced and stored in the skin, thus affecting our skin color,” explains study co-author Desmond Tobin, PhD, a professor of dermatology at University College Dublin. “A darker skin produces more melanin, which can help prevent UV light from damaging our DNA and so offers protection against skin cancer.”

It is well established that Native Americans are genetically related to East Asians, the initial settlement of the Americas occurring some 15–20,000 years ago, through migration from Eastern Siberia into North America. As a consequence, genetic variations in Native Americans are often shared with East Asians.

“Our work demonstrates that lighter skin color evolved independently in Europe and East Asia,” notes lead study investigator Kaustubh Adhikari, PhD, a statistical geneticist at UCL. “We also show that this gene was under strong natural selection in East Asia, possibly as an adaptation to changes in sunlight levels and ultraviolet radiation.”

Remarkably, the researchers were able to show that MFSD12 was under natural selection in East Asians after they split from Europeans around 40,000 years ago and was then carried over to America by ancient migrations of Native Americans. It is the first time this gene has been linked to skin color in Native Americans and East Asians.

“Interestingly, this gene also turned up in the skin color study in Africans, but the variants were entirely different than those we observe in our study, highlighting the huge genetic diversity in humans and the need to diversify our study populations,” emphasizes senior study investigator Andres Ruiz-Linares, PhD, a professor at UCL Genetics Institute, who led the CANDELA project spanning participants from five countries: Brazil, Colombia, Chile, Mexico, and Peru.

Human physical diversity has fascinated biologists for centuries, and despite the discovery of hundreds of genes related to such variation, there is still a lot to be understood to gain a fuller picture. Scientists have been calling for more diversity in genetics research to ensure that everyone benefits from the medical outcomes of research.

Only recently scientists published the first major study on the genes linked to skin tone diversity in Africa. Latin Americans are similarly underrepresented in genetics research, particularly in pigmentation research.

In addition to skin tone variation, the scientists also noted a wide variation in eye color among Latin Americans. “Just like skin color, early research on eye color was Europe-centric, and mostly focused on the distinction between blue vs. brown eyes. But we show that eye color is a broad continuum, and by studying the subtler variation within brown to black, we found two new genes linked to it,” concludes study co-author Anood Sohail, a doctoral candidate at the University of Cambridge.

The study’s findings help explain the variation of skin, hair, and eye color of Latin Americans, shed light on human evolution, and inform an understanding of the genetic risk factors for conditions such as skin cancer.

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