Why do Khosian people look East Asian?

Who the Khoisan are

The Khoisan are the indigenous people of Southern Africa, best known to the wider world for their languages built on distinctive click consonants. Their genetic line diverged from all other human populations more than 100,000 years ago, making them one of the most ancient distinct lineages alive today. Khoisan subgroups show more genetic difference among themselves than some Europeans and East Asians do from each other. That internal diversity alone tells you how deep their roots go.

The features everyone notices

The Khoisan often possess light brown skin, distinctive epicanthic eye folds, and facial structures that can resemble East Asian features. The epicanthic fold is the specific trait that catches people's attention: it is a vertical fold of skin on either side of the nose, sometimes covering the inner corner of the eye.

Why the question is backwards

These traits are not due to recent Asian ancestry. They are ancient, ancestral human features retained by the Khoisan, who represent one of the oldest human lineages, dating back over 100,000 years.

The Khoisan carry epicanthic eye folds and high cheekbones, traits that anthropologists believe were present in early human ancestors long before populations began migrating out of Africa. These features were not borrowed from East Asia; they are part of an ancient African inheritance that predates the existence of modern Asian populations.

The Khoisan have no Asian ancestry and are some of the oldest communities in the world. The similarity runs in only one direction of time: the Khoisan had those features long before any East Asian population existed.

What science says about the fold itself

Though the epicanthic fold's appearance in peoples of Southeast Asia can be linked to possible descent from cold-adapted ancestors, this does not explain its occurrence in various African peoples. The fold found in many African people has been tentatively linked to protection for the eye from high levels of ultraviolet light found in desert and semi-desert areas. The exact evolutionary function and origin of epicanthic folds remains unknown.

One strong possibility is that the fold evolved independently in Africa and in Asia for different environmental reasons, a phenomenon scientists call convergent evolution, where two separate lineages arrive at the same physical solution to different pressures. Even though tens of thousands of papers have been published on genes and their effect on human features, there are just a handful dealing with the epicanthic fold, and none of them have identified the genes originating it.

Every baby throughout the world is born with epicanthic folds. In some people the folds are retained into adulthood, while in others they reduce at an early age. So in one sense, this is a feature all humans start with, and the real question is which populations retained it.

The bigger picture

The Khoisan and their ancestors have been the largest populations since their split with the non-Khoisan population roughly 100,000 to 150,000 years ago. In contrast, the ancestors of non-Khoisan groups, including Bantu speakers and non-Africans, experienced population declines after the split and lost more than half of their genetic diversity.

Every human being alive today descends from ancestors who came out of Africa. The Khoisan simply never left, and they retained features that the rest of humanity carried with them when they did. When you see those eyes and cheekbones, you are looking at the face of our shared ancestors, preserved in one of the oldest unbroken lineages on the planet.