UPDATED 9 22 2021

Note: The above images are cherrypicked. Most Ainu their phenotypes are predominantly Mongoloid, with some Caucasoid influence.


The Ainu are a near-extinct minority group native to northern Japan. Their pseudo-Caucasoid appearance has long perplexed Western anthropologists and their phenotype is unique among East Asian populations. Ainu often have thick and full beards, increased body hair, “European” eyes and eye sockets, and lighter skin pigmentation, relative to other Japanese people. Their origin is mysterious and many Western anthropologists have proposed that the Ainu may be a long-lost tribe of ancient Indo-Europeans.


The phenotypic similarities between Ainu and Europeans were officially noted by the Japanese government when their tourist board published the following ethnic description, written by the award-winning author Kyōsuke Kindaichi:

Many have wavy hair, but some straight black hair. Very few of them have wavy brownish hair. Their skins are generally reported to be light brown. But this is due to the fact that they labor on the sea and in briny winds all day. Old people who have long desisted from their outdoor work are often found to be as white as western men. The Ainu have broad faces, beetling eyebrows, and sometimes large sunken eyes, which are generally horizontal and of the so-called European type. Eyes of the Mongolian type are rare but occasionally found among them

In 2001, a craniometric study was conducted on the Hokkaido Jōmon, from whom the Ainu trace ~80% of their ancestry. The authors found numerous physical similarities between Jōmon and European skulls, and suggested that the Jōmon were at least partially descended from a ‘Eurasian’ population of the Upper Paleolithic (predating the expansion of modern East Asians) that was also ancestral to Europeans and Native Americans.

The fact that Late Pleistocene populations in northwest Europe and northeast Asia show morphological similarities suggests that there may have been actual genetic ties at one time. Those morphological similarities can still be shown between Europe and the descendants of the aboriginal population of the Japanese archipelago, i.e., the Ainu.

— Brace et al. 2001, Old World sources of the first New World human inhabitants: A comparative craniofacial view

Note: For reference, modern Japanese are 8% to 45% Jōmon, depending on how the ancestry is tested for.

Genetics

Fascinatingly, modern genetic studies have confirmed that the Ainu do share some sort of ancestry with Caucasoids, and they also suggest that this ancestry can be traced back to ancient Siberia.

In 2015, a study published in Nature journal found that the Ainu exhibit medium frequencies of facial feature genes that are commonly found among Europeans and Middle Easterners but are absent from other East Asian populations. This was confirmed by a 2021 study, which found that the Hokkaido Jōmon, from whom the Ainu descend, had “European” facial genes, while southern Jōmon groups did not. Of all Jōmon groups, the Hokkaido group was the least closely related to modern East Asians. Though, the vast majority of their ancestry is, fundamentally, of East Asian origin. A 2019 study modeled a female Jōmon (named “F23”) as 86% East Eurasian, and 14% West Eurasian (Caucasoid).

The Caucasoid facial features of the Ainu/Jōmon peoples are likely derived from an Ancient North Eurasian (ANE) or Ancient North Siberian (ANS) source. Although this link has not yet been confirmed, these populations are the perfect candidates. Both were archaic West Eurasian (Caucasoid) peoples who inhabited Siberia during the Ice Age, before the formation of the Jōmon population. The ANE contributed ancestry to:

  • Native Americans (33%), who have a similar appearance to Ainu (see Kennewick man, below)
  • Modern Northern Europeans (highest ~35% in Finland, lowest ~22% in England)
  • Proto-Indo-Europeans (50%)
  • Neolithic Iranians (50%)
  • + all modern Siberians and many other populations throughout Eurasia

Furthermore, the ANE appear to have been affiliated with the Paleolithic microblade culture, which arrived in Hokkaido around 25,000 years ago, likely through a migration of ANE-related peoples.

Kennewick man was mistaken as a Caucasoid by many anthropologists:


A genetic study published in 2020 suggested that the Hokkaido Jōmon were partially descended from the ANE. However, they could not confirm the relationship.

if the assumption is correct, then the [Siberian microblade culture] was brought to the Japanese archipelago by the [Northeast Asian / East Siberian / Native American] population who must have had substantial gene flow from [Ancient North Eurasians]

This was supported by a 2021 study, which suggested that “the [Ancient North Eurasian] rather than [Ancient North Siberian] individual was responsible for the [West Eurasian] genetic component in the present-day Northeast Asians.” Unfortunately, a direct ANE/ANS-to-Jomon relationship could not be confirmed in this study either.

Conclusion

So, are the Ainu a “long-lost tribe of ancient Indo-Europeans”? Definitely not. But we do know that the Ainu have (and that the Jōmon had) “European” facial genes. They may have somehow developed these specific facial genes independent of Caucasoid admixture, but that is an extremely implausible (if not near-impossible) scenario. Although we cannot confirm where these genes originated, or how they ended up in the Ainu population, the most likely candidates are the only Caucasoid populations of ancient East Eurasia, who also happened to be ancestral to the Proto-Indo-Europeans: The Ancient North Eurasians/Siberians.

Update!

Another 2021 study (published five days ago) has successfully confirmed the relationship between Jomon and Ancient North Siberians: They tested “whether the Jomon had any contact with continental Upper Paleolithic people after the divergence of their lineage” and found that the results supported “gene flow between the ancestors of Jomon and Ancient North Siberians, a population widespread in North Eurasia before the LGM.”

Expect more interesting finds on this topic in the future.