Review
Refinement of Poultry Standing in Japan Based on Recent Anthropo-ornithological Perspectives
2025 Volume 62 Article ID: 2025029
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2025 Volume 62 Article ID: 2025029
Poultry meat and eggs are important sources of high-quality animal protein worldwide. However, poultry in Japan has historically been regarded as a symbolic or spiritual entity more than as a food source, as its roles are deeply embedded in Japanese consciousness and society. Current evidence indicates that chickens first appeared in Japan during the Yayoi period, approximately 2,000 years ago, coinciding with a period of active human migration to the Japanese archipelago. Since then, poultry has played notable roles in Japanese art, literature, mythology, and folktales. Recent advancements in molecular clock analysis or the detection of genomic modifications, such as introgression, deletions, mutations, and viral infection from trace fossil/live samples necessitate the continual revision and refinement of existing theories about human and animal history across several academic disciplines. Therefore, the objective of the present review was to elucidate the distinct and multilayered relationship between humans and poultry in Japan, incorporating recent anthropological and ornithological perspectives.
Human–animal relationships vary considerably across cultural backgrounds. This observation is particularly applicable to human–avian relationships in Japan, where birds have historically been regarded more as symbolic or spiritual entities than as food sources—a perspective traditionally examined within the field of cultural anthropology.
However, recent advances in genomic analysis of both humans and birds have created a need to refine our understanding of human–avian relationships in Japan. Accordingly, this review seeks to approach cultural anthropology from an evolutionary biological perspective.
This review aims to integrate insights from evolutionary biology into the cultural–anthropological discourse, thereby refining our understanding of human–avian interactions in the Japanese context.
Poultry refers to “Domestic fowl collectively; birds which are commonly reared for their flesh, eggs, or feathers, such as chickens, ducks, geese, and turkeys.”[1]. A report from the United Nations Food and Agriculture Organization (FAO) lists the following 10 species, which account for only 0.09% of more than 11,200 known avian species, as poultry[2]. These belong to three orders: Galliformes, including the chicken (Gallus gallus)[3], turkey (Meleagris gallopavo)[4], guinea fowl (Numida meleagris), Japanese quail (Coturnix japonica), ostrich (Struthio camelus), and pheasant (Phasianus colchicus); Columbiformes, including the pigeon (Columba livia domestica)[5], and Anseriformes, including the goose (Anser domesticus)[6], muscovy duck (Cairina moschata)[7], and mallard duck (Anas platyrhynchos)[8].
Among the 35 billion head of poultry worldwide, chickens accounted for 91.2%, followed by ducks (6.0%), geese (2.0%), turkeys (0.7%), and others (0.07%) in 2023[9]. Chickens contribute 83.4% of the global poultry meat production, followed by ducks at 7.6%, geese at 6.0%, and turkeys at 3.1%. Chickens provide 93% of eggs worldwide . At the regional level, non-chicken poultry species lay 10% of all eggs in Asia, 1% in the Americas, 3% in Latin America, 0.6% in Oceania, and 0.5% in Europe[9]. Eggs of other birds, such as ducks and ostriches, are consumed regularly, however, less commonly than chicken eggs. People also eat the eggs of reptiles, amphibians, and fish. Fish eggs consumed as food are known as roe or caviar[10]. However, regional differences occur in the sources of non-poultry eggs consumed as food; for example, the food production of eggs from species other than chickens is almost non-existent in Africa[9]. A structural and historical overview of the egg industry is provided by Stadelman[11].
Chickens are the leading poultry species raised worldwide. The number of ducks reared in Asia is higher than that in other regions, whereas the number of turkeys is highest in North America, followed by Europe and Asia[9]. Africa and Asia lead in guinea fowl and geese rearing[9]. Additionally, poultry may be used for game purposes[12].
The Japanese poultry industry grew rapidly after World War II[13]. In 2024, the number of layer chickens was approximately 170 million, with egg production of roughly 2.5 million tons[14]. The number of layer farms had decreased to 1,700; however, the average number of birds raised per household was roughly 79,000. Approximately 145 million head of broilers were present in Japan in 2024 and roughly 1.7 million tons of chicken meat was produced. The number of broiler farms had decreased to 2,050 and the average number of birds raised per household was approximately 70,700[14].
Birds are terrestrial oviparous vertebrates, the body mechanics of which have been evolutionarily adapted for flight. In Linnaeus’s original taxonomy, birds were categorized as Class II: Birds within the animal kingdom, based on their distinct external morphology[15]. Linnaeus believed that all species were created by God, stating “All created things are proof of the Divine power and wisdom, and fertile sources of human happiness”[15].
Richard Owen, a prominent 19th-century British anatomist and paleontologist, also believed that the creation of species followed predetermined divine laws rather than the mechanism of natural selection[16]. Owen introduced the concept of an archetype, i.e., a common structural blueprint underlying all vertebrates[17].
Charles Darwin observed the morphological similarities of embryos among animal species by providing the following examples: 1) certain organs that later diverge significantly in structure and function are similar during the embryonic stage; 2) the embryos of distinct animals within the same class are extremely similar; 3) determining whether an embryo belongs to a mammal, bird, or reptile is impossible[18]. Darwin begins his book “On the Origin of Species” with a discussion of “Variation under Domestication” in Chapter 1, followed by “Variation under Nature” in Chapter 2[18]. This chapter structure suggests that Darwin foresaw the potential for selective breeding of animals and plants, whereby traits of interest to humans could be enhanced through intentional selection. He described limitations in his theory by pointing out the absence or rarity of transitional varieties and stated that “As long as most of the links between any two species are unknown, if any one link or intermediate variety be discovered, it will simply be classed as another and distinct species”[18]. In a later edition, Darwin quoted Sir J. Lubbock in saying that “every species is a link between other allied forms,” to support his argument on the gradual nature of species variation[19].
Darwin’s publication sparked “The 1860 Oxford evolution debate” at the Oxford University Museum in 1860, between those who accepted the new theory of evolution of living things (including Thomas Henry Huxley) and those who rejected it (including Bishop Samuel Wilberforce)[20]. Huxley supported Darwin’s theory and stated that “the phrase ‘Birds are greatly modified reptiles’ would hardly be an exaggerated expression.”[21]. Since then, Darwin’s theory of evolution has prompted a search for transitional fossils that bridge major evolutionary gaps, which has been later confirmed by discoveries of the first fossil feather[22] and an Archaeopteryx fossil with feathers preserved in situ from Jurassic deposits[23]. These findings revived an argument on the “missing link” during evolution. A discovery of two feathered dinosaurs from northeastern China[24] provides solid evidence that birds inherited feathers from theropods. Accordingly, clade Dinosauria, which had once been classified as a distinct tribe or suborder of Saurian reptiles by Richard Owen[25] is now considered an ancestor of the neolithic birds. The recent discovery of a nearly complete and uncrushed fourteenth specimen with a mosaic of traits present in Archaeopteryx refines ecological predictions and elucidates the unique evolutionary history of the Archaeopterygidae, providing clues regarding the ancestral avian condition[26]. Additionally, a Mesozoic fossil of Asteriornis maastrichtensis, gen. et sp. nov. from the Maastrichtian age has been discovered in Belgium (66.8–66.7 million years ago), filling a phylogenetic gap in the early evolutionary history of crown birds[27].
The evolutionary flight adaptation in birds is associated with notable anatomical and physiological modifications. A symbolic example is the highly efficient avian respiratory system, characterized by non-tidal (unidirectional) airflow facilitated by air sacs[28,29,30], and a pneumatic bone system that functions as part of the respiratory system[31]. Birds also have highly efficient oxidative phosphorylation with low free radical production in the mitochondria of major tissues[32], which allows them to respire efficiently and avoid excess oxidative stress. Another unique characteristic of birds is the presence of nonvisual photoreceptors deep within the brain, which are a critical component of the timing of seasonal reproduction[33]. Furthermore, the expression of a gene encoding type 2 iodothyronine deiodinase in the mediobasal hypothalamus, which catalyzes the intracellular deiodination of thyroxine (T4) prohormone to the active 3,5,3ʹ-triiodothyronine (T3), is induced by light in Japanese quail[34].
The emergence of next generation gene sequencing technology has enabled genomic and gene expression analyses. A cladistic study of sex chromosomes revealed that the ancestors of reptiles and birds (Dinosauria) diverged from mammals 310 million years ago[35]. The progenitor avian organisms that evolved from theropod dinosaurs have maintained multiple lineages from the Cretaceous Period in the Mesozoic Era; the number of avian species exploded through adaptive radiation during the Cenozoic era[35]. Genomic information on various birds, including both extant and extinct species, has led to considerable discussion of the evolution, speciation, and domestication of birds. Accordingly, the revised dinosaur evolutionary tree has two main branches (Figure 1), one including Herrerasauridae and Sauropoda, and the other including Theropoda and Ornithischia[36,37].
Recent research has led to the prevailing theory that birds are direct descendants of theropod dinosaurs that survived the Cretaceous–Paleogene (K-Pg) boundary mass extinction event[37,38], which occurred 66 million years ago[39]. Extinction rates at the family level during this mass extinction event are estimated to be 30% (64/210) among vertebrates, 23% (5/22) among mammals, and 75% (9/12) among birds[40]. Thus, all birds existing today are descendants of a limited number of families that survived the K-Pg boundary mass extinction. Following a revision of the classification system for all organisms, reptiles and birds were reorganized under class Reptilia, and five subclasses were established: Aves, Crocodylomorpha, Testudinata, Squamata, and Rhynchocephalia[41]. Revisions to the classification system continued based on new findings and birds were placed within clade Theropoda[42]. More recently, it has been reported that the ancestor of birds that evolved from theropod dinosaurs diverged into Paleognathae and Neognathae during the Cretaceous Period, with the Neognathae further diverging into Galloanserae and Neoaves[43]. As of 2024, all existing bird species have been reclassified into 44 orders, 254 families, 2,392 genera, and 11,276 species[43], which occupy 14.9% (11,276/75,923) of the known vertebrate species[44]. It should be emphasized, however, that accurately defining avian species has long been a challenge, particularly in cases, such as allopatric populations, where no clear threshold has yet been established to determine when diverging lineages have become sufficiently distinct to warrant full biological species status[45]. The phylogenetic relationships between major avian and non-avian groups are shown in Figure 2[46,47,48,49].
The red junglefowl (G. gallus) is generally considered to be the major ancestor of the domestic chicken[50,51,52]. However, based on mitochondrial DNA (mtDNA) sequences, a strong indication of inter-species hybridization has been observed between the grey junglefowl (Gallus sonneratii) and red junglefowl, and between the grey junglefowl and the Ceylon junglefowl (Gallus lafayettii)[53]. A yellow skin mutation observed in various chicken breeds is thought to have originated from the grey junglefowl[54]. The finding that different Gallus species may have contributed to the genetic makeup of the domestic chicken is supported by a recent molecular study[55].
Extensive bidirectional gene introgression between the grey junglefowl and domestic chickens, a few gene introgressions between domestic chickens and the Ceylon junglefowl, and a single gene introgression between domestic chickens and the green junglefowl (Gallus varius) have been observed[55].
Recent genomic data have revealed that the red junglefowl subspecies Gallus gallus spadiceus is the main wild ancestor of chickens, which translocated across South and Southeast Asia and locally interbred with other red junglefowl subspecies and other junglefowl species[56]. Ancestral populations of Thai indigenous chickens were large, and part of the red junglefowl population gene pool was not involved in domestication. Additionally, chicken domestication occurred independently across multiple regions in Southeast Asia[57]. The origin of the domestic chicken has been reported based on modern biological and zooarchaeological approaches[58]. A Gallus species cladogram is shown in Figure 3[59].
Cladogram of species in the genus Gallus[59] (modified).
Based on archaeological and paleontological evidence, the earliest known bird in Japan was Fukuipteryx prima, a primitive avialan (early bird-like dinosaur) discovered from the Early Cretaceous Period in the Kitadani Formation in Fukui Prefecture[60]. The earliest evidence of true Neornithes members in Japan includes Early Plotopteridae specimens (Aves) from the Itanoura and Kakinoura Formations (late Eocene to early Oligocene) in Saikai, Nagasaki Prefecture, western Japan[61]. True Neornithes have been discovered in the Late Oligocene formations of Fukuoka Prefecture; these include two new species of large, flightless seabirds from family Plotopteridae[62].
The oldest evidence of a domestic bird excavated in Japan is a chick femur sample found at Karako-Kagi village in Nara, dated to between the 4th and 3rd centuries BCE[63]. These dates correspond to the Yayoi period of Japanese history, when paddy rice farming was introduced from the Eurasian continent.
In ancient times, chickens were mainly used for timekeeping, cockfighting, fortune-telling, and rites, rather than for food consumption. For example, during the reign of Emperor Yūryaku (456–479 CE), cocks were pitted against each other by the local ruling family. The first written record of a chicken in Japan is a long-crowing bird described in the Kojiki (712 CE)[64], which was written at the end of the Yamato (Kofun) period. Since then, chickens have held symbolic significance in Japan.
The Toh-Kei Jin-jya (meaning: cock-fighting shrine) located in Tanabe City, Wakayama Prefecture was registered as a World Heritage sacred site of the Kii Mountain Range in 2016. This Shinto shrine was constructed in 419 CE and named for a historical event in which Kumano-Betto Tanzo, the father of Benkei, allowed a red hen and a white hen to fight. The shrine is proximate to the Kumano Sanzan mountains (meaning: three Kumano mountains), so it was a popular destination for worship during pilgrimages to Kumano. In a description of the battle of Dan-no-ura in “The Tale of the Heike”, Kumano-Betto and others decided to side with Genji in a cock fight, and the chicken carrying Genji’s flag color won.
Among several indigenous chicken breeds in Japan, 17 breeds are designated as Natural Monuments (Table 1), which are protected under the “Law for the Protection of Cultural Properties” (Law #214, May 30, 1950, amended to Law #68, June 17, 2022). In Japan, various natural features, including plants, animals, and geological formations are designated as cultural assets that warrant protection[13].
| Year of designation as “Natural Monument of Japan” | ||
| 1 | Japanese Silkie (Ukkokei) | 1942 |
| 2 | Japanese Small Rumplessness (Uzura-Chabo) | 1937 |
| 3 | Japanese Brave (Kawachi-Yakko) | 1943 |
| 4 | Japanese Black (Kuro-Kashiwa) | 1951 |
| 5 | Japanese Good Crower (Koeyoshi) | 1937 |
| 6 | Kagoshima Game (Satsuma-Dori) | 1943 |
| 7 | Japanese Creeper (Jitokko) | 1943 |
| 8 | Japanese Elegancy (Shoukoku) | 1941 |
| 9 | Japanese Bantam (Chabo) | 1941 |
| 10 | Japanese Extremely Long Tail (Tosa-no-Onagadori) | 1923 *) |
| 11 | Japanese Red Crower (Toutenkou) | 1936 |
| 12 | Japanese Black Crower (Toumaru) | 1939 |
| 13 | Japanese Dainty (Hinai-Dori) | 1942 |
| 14 | Japanese Saddle Hackle Dragger (Minohiki) | 1940 |
| 15 | Japanese Small-sized Hackle (Minohiki-Chabo) | 1937 |
| 16 | Japanese Old Type (Jidori) | 1941 |
| 17 | Japanese Game (Shamo) | 1941 |
*) Redesignated as "Special Natural Monument of Japan" in 1952
Cited from: https://www.hiroshima-u.ac.jp/en/research/now/no27/no27_1
The phylogenetic relationships between Japanese native fowl have been extensively studied[65,66]. Cluster analyses revealed that 15 Japanese native chicken breeds may be divided into five groups: the first group consists of Hinai-dori, Koeyoshi, Tomaru and Shamos; the second includes Chabos, Satsuma-dori and Nagoya; the third consists of Totenko and Onagadori; and the fourth and fifth groups include Tosa-jidori and Shokoku, respectively. Indonesian native fowl are closely related to the second group[67]. An analysis of mtDNA sequences shows that Japanese native chickens have multiple origins[68]. These results suggested that chickens with diverse genetic backgrounds were introduced across various geographical regions in Japan, where they were selected according to region-specific criteria. Exploring the roles of poultry incorporated into regional historical events or monuments, based on a combination of anthropological and ornithological evidence, is valuable for a deeper understanding of cultural heritage in Japan.
The translocation of domestic animals and plants has been historically associated with human migration. Homo sapiens evolved in Africa during the late Middle Pleistocene Period[69] and migrated to Southeast and East Asia between 46,000 and 63,000 years ago[70]. Humans have historically migrated to every habitable continent, however, population sizes were small, and most humans lived primarily by hunting and gathering or nomadically before the advent of plant and animal domestication[71].
During the eastward migration of H. sapiens from Africa, several gene flow events occurred among the Neanderthals, Denisovans, and early modern humans[72]. The history of multiple Denisovan introgression events in modern humans has been reviewed by Ongaro et al.[73]. These gene flow events may have influenced the genetic makeup of present-day humans. For example, the ability of Tibetans to adapt to the low-oxygen environment of high-altitude plateaus has been linked to the inheritance of the endothelial PAS domain-containing protein 1 (EPAS1) gene from Denisovan ancestors, which plays a key role in adaptation to hypoxia[74]. An analysis based on the Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library (JEWEL) showed that 11 Neanderthal-derived segments were associated with seven diseases, including type 2 diabetes, coronary artery disease, stable angina pectoris, atopic dermatitis, Graves’ disease, prostate cancer, and rheumatoid arthritis. A Denisovan-derived segment at NKX6-1 is associated with type 2 diabetes and candidate genetic loci have been identified[75]. The recent discovery of a male Denisovan mandible from the Pleistocene in Taiwan[76] has added a new dimension to the study of anthropology. With the advent of next-generation sequencing and population-based paleogenomic research, the roles of ancient DNA have been investigated at scales from continental human migrations to detailed analyses of specific archaeological sites, domestication processes, and the prehistoric spread of viral diseases[77,78].
The earliest evidence of H. sapiens activity in the Japanese archipelago consists of stone tools dated to approximately 38,000 years ago[79,80]. Upper Paleolithic sites are scattered across Japan and such stone tools have been excavated from the Ishinomoto site in Kagoshima Prefecture, the Sozudai site in Ōita Prefecture, and the Odai Yamamoto I site in Aomori Prefecture[81,82]. More than 10,000 Palaeolithic sites have been discovered on the Japanese archipelago, most of them dating to Marine Isotope Stage 2 (29,000–14,000 years ago)[83]. The subsequent Neolithic Period (16,000–3,000 years ago) is called the Jomon period in Japan, as the period is characterized by straw-rope pottery. The sea level at the Last Glacial Maximum (23,000–19,000 years ago) was 120–130 m below the present level[84,85]. Consequently, animals migrated across land bridges that connected the Japanese Islands and the adjacent continent during the Pliocene and Pleistocene[86]. During the Jomon period in Japan, the Holocene glacial retreat was associated with abrupt warming, which resulted in rapid melting of the remaining ice sheets and sea level elevation. The relative sea level was 2–3 m higher than that of the present level 7,000–4,000 years ago in the area north of Tokyo Bay[87,88]. By the time of the Holocene glacial retreat, the sea level restricted the terrestrial migration of humans and animals to the Japanese archipelago, and this isolation from the Eurasian continent allowed the development of endemic species[89]. Accordingly, among the 690 known bird species in Japan, 16 (2.3%) are endemic[90].
Archaeological evidence indicates that the management of plant resources in Japan began about 7,000 years ago. The deliberate cultivation and utilization of various plant species in proximity to settlements during this period has been documented. Notable examples include Castanea crenata (Japanese chestnut), Toxicodendron vernicifluum (used in the production of lacquerware), Cannabis sativa, Lagenaria siceraria var. siceraria (bottle gourd), and Perilla frutescens var. frutescens. These findings suggest that the Jomon people engaged in a sophisticated form of plant resource management, with a particular emphasis on woody species, which they systematically tended and intensively utilized[91,92].
The Jomon period was followed by the Yayoi period (900 BCE to 300 CE), which was characterized by paddy rice farming, presumably brought in by large-scale immigrants from the Eurasian continent. The dual-structure model[93] suggests that the modern Japanese population formed as an admixture of indigenous hunter–gatherer Jomon people originally from Southeast Asia during the Upper Palaeolithic, and paddy rice-farming Yayoi migrants from Northeast Asia. The “dual structure hypothesis” of Hanihara proposes two genetic layers in the population history of the Japanese archipelago. Although this theory was initially widely accepted, recent advances in genomic analysis have suggested more complex social relationships between Neolithic (corresponding to the Jomon period) and Bronze Age (corresponding to the Yayoi period) peoples[94]. A tripartite origin for the Japanese population has been proposed, including a first wave during the Jomon period, with a small effective population size of ~1000 immigrants over several millennia; a second wave of Yayoi people of Northeast Asian ancestry who brought rice cultivation; and an unexpected third influx of East Asian ancestry during the Yamato (Kofun) period (300–800 CE). These three ancestral components continue to characterize present-day populations, supporting a tripartite model of Japanese genomic origins[95]. The applicability of the tripartite model to Japanese populations throughout the archipelago has been evaluated and an extremely strong correlation has been observed between the Jomon ancestry and genomic variations among individuals[96].Furthermore, the genetic legacy of the Jomon ancestry underlies a high body mass index. Genome-wide association analysis with rigorous adjustments for geographical and ancestral substructures has identified 132 variants that are informative for predicting individual Jomon ancestry[96]. Analysis of the Jomon-derived variants among 10,842 modern Japanese recruited from all over Japan has revealed that the admixture proportions of the Jomon people vary between prefectures, probably due to the prehistoric population size difference[97].
It has been suggested that the expansion of wet rice cultivation may be linked to hypothetical language family dispersal models, including dispersal from China southward by Sino-Tibetan and Austronesian groups[98]. The dispersal of rice in South Asia occurred after Indo-Aryan and Dravidian speakers adopted rice from speakers of lost languages in northern India[98]. Thus, it was hypothesized that the genetic diversity of the population that migrated to the Japanese archipelago during the Yayoi period was extremely high and the genetic component of the present-day Japanese population is much more complicated than previously thought. The Japanese population was optimally divided into three clusters through JEWEL analysis, with different intensities of Jomon influence detected in Okinawa (Jomon ancestry dominant), northeastern Japan (Northeast Asian ancestry dominant), and western Japan (East Asian ancestry dominant)[99]. This result strongly suggested that multiple waves of human migration from the Eurasian continent arrived on the Japanese archipelago during the Yayoi period, facilitating the transmission of wet rice agriculture and the introduction of domesticated species, including the domestic chicken. An examination of historical records shows that this phylogenetic result is consistent with the view that Japanese Shamo originated from Southeast Asia and mainland China independently, however, has been geographically mixed thereafter[100].
This review examined poultry in Japan from anthropological, ornithological, ritualistic, mythic, and artistic attributes of Japanese society. Recent advancements in molecular clock analysis and the detection of genomic modifications from fossil or body samples require the continual adaptation and refinement of existing theories of human and animal history across academic disciplines.
Future studies on the human–poultry relationship should integrate recent molecular-based anthropological and ornithological findings with the humanistic and social aspects of poultry that are deeply embedded in Japanese society.
I would like to express my sincere appreciation to the editorial board of the Journal of Poultry Science for the opportunity to prepare this manuscript.
The author declares that no AI or AI-assisted technologies have been used in the production of the submitted work.
The authors declare that there is no conflict of interest.
