Around 200,000 years ago, the first Homo sapiens lived in Africa, the cradle of humanity. From there, small groups gradually spread across Europe and Asia.
During the last Ice Age, sea levels dropped by as much as 120 meters, exposing a landmass that now lies underwater: the Bering Land Bridge. Some of the first populations to reach the Americas may have crossed through this corridor. This is one of several hypotheses that seek to explain how Homo sapiens arrived in this part of the world.
But what does that have to do with the eye features?
Part of the answer may lie in these migrations. Some Indigenous peoples of the Americas possess the epicanthic fold, an anatomical feature of the upper eyelid that gives the eyes an almond-shaped appearance. If some of the continent’s earliest inhabitants came from Asia, certain genetic traits present in those populations may have been passed down through generations and remain visible today.
Adapting to Extreme Environments
Another hypothesis points to natural selection. In biology, environmental conditions can influence how common certain physical traits become within a population. Some researchers have suggested that the epicanthic fold may have provided additional protection for the eyes in environments with intense solar radiation, strong winds, and high levels of light reflected by snow.
In the Andes, for example, it is well documented that human populations have developed a range of adaptations to survive in extreme environments. Researchers have identified physiological changes associated with life at high altitude, including greater lung capacity and differences in how the body transports and uses oxygen. These characteristics are the result of long-term adaptation to demanding conditions.
The migration and adaptation hypotheses are not mutually exclusive. Both may have contributed, to different degrees, to the current distribution of this trait.
The Peruvian geographic study
Between 2005 and 2015, the National Geographic Society led the Genographic Project, a global initiative that analyzed genetic samples from more than 830,000 people across 140 countries with the goal of reconstructing the migratory routes of our species.
In Peru, studies conducted by molecular biologist and geneticist Ricardo Fujita estimate that around 70% of the average genome of the population is of Indigenous ancestry. In Lima, the figure is estimated to be around 68%, while in some Andean regions it reaches as high as 95%.
Behind these percentages lies a story of continuity connecting millions of Peruvians to the continent’s earliest inhabitants. As Fujita puts it, “If we put all Peruvians into a blender, 70% of our genome would be Indigenous and Andean.”
We are not so different
From a biological perspective, the concept of “race” has no scientific basis. The physical differences observed among human populations are the result of thousands of years of adaptation to different environments. All humans share a common origin in Africa.
Culturally, Peruvian identity emerged through multiple historical processes, including pre-Columbian civilizations, colonization, migration, and globalization. Genetics speaks to our origins, while culture reflects how those origins continue to interact with the present.
Human adaptation has left traces beyond our bodies. It has also shaped knowledge systems developed over generations to thrive in complex environments. In the Andes, for example, agricultural terraces, hydraulic systems, and a remarkable diversity of crops enabled communities to cope with temperature fluctuations, water scarcity, and other environmental challenges.
Today, in the context of climate change, a growing number of studies have found that territories managed by Indigenous peoples often maintain high levels of biodiversity, store large amounts of carbon, and experience lower rates of deforestation than comparable areas. These findings suggest that knowledge developed through generations of interaction with specific ecosystems can complement contemporary strategies for conservation and climate adaptation.
So-called “almond-shaped eyes” are much more than a physical trait. They also reflect a story of migration, adaptation, and survival that began thousands of years ago and remains part of who we are today.
And this is only one small human characteristic carrying thousands of years of history. What topic would you like us to explore next?
