**5. Plastic behavior in the utilization of animal resources**

The behavioral plasticity of Paleolithic people is observable in their material culture and hunting-gathering actions. The Paleolithic people in Sakitari Cave mostly consumed freshwater crabs (Japanese mitten crab) and freshwater snails. They also ate small vertebrates such as mice, birds, lizards, snakes, frogs, and fish (freshwater and marine). The food waste in Sakitari indicates that small, nocturnal animals living in or near the river were dominant. As in the general example of island fauna, the fauna of Okinawa Island lacks large terrestrial mammals (**Figure 5**). At the first stage of human arrival, there were two species of middle- or small-sized deer and one species of a middle-sized tortoise [33], but they went extinct probably earlier than 30,000 years ago [42, 54]. Based on the limitedness of the terrestrial fauna, some researchers theorize that Paleolithic people were unable to maintain their population on the small island [61, 62]. However, research of the Sakitari remains revealed that the Paleolithic people maintained their population for nearly 20,000 years by consuming small, aquatic animals, which generally are highly reproductive and densely inhabited the area compared to large and middle-sized mammals. This unique, effective use of animal resources enabled the Paleolithic hunter-gatherers to live on relatively small islands for a long time.

The extensive consumption of marine resources was reported in ISEA [19, 23–26]. Paleolithic immigrants who came to this area developed diverse fishing and shellfishing

**141**

**6. Conclusion**

*The Migration, Culture, and Lifestyle of the Paleolithic Ryukyu Islanders*

other seasons, though we do not have any evidence at present.

uted throughout the Ryukyu Islands remain controversial.

by Paleolithic Ryukyu Islanders suggest the relation to the ISEA.

*sapiens* to migrate to various environments all over the world.

activity. The exploitation of variety of marine resources may be one of the factors that enabled Paleolithic migration to the variety of islands. As indicated by the studies on human remains and shell artifacts, relation between Okinawa and ISEA is suggested again in the viewpoint of aquatic resource usage. However, dominance of the freshwater animals is the unique point of Paleolithic Okinawa. One reason may be the limited terrestrial animals, and another reason may be seasonality. The oxygen isotope study on freshwater snails indicated that these freshwater animals were consumed mainly in autumn [16]. Paleolithic people of Okinawa may have used more marine resources in

Another notable behavior of Paleolithic Ryukyu Islanders is the possible translocation of wild pigs earlier than 20,000 years ago. Researchers have reported that the Pleistocene translocation of animals occurred in Cyprus around 11,000 years ago [63] and Manus Island around 13,000 years ago [64]. In the case of the Ryukyu Islands, after the extinction of the endemic deer between 30,000 and 35,000 years ago, wild pigs appeared and increased in number around 20,000 to 27,000 years ago [31, 39, 54, 65]. Because Okinawa Island was isolated from the Eurasia continent, mainland Japan, and the remaining Ryukyu Islands during the Pleistocene [27], the increase in the wild pig population might have resulted from people translocating pigs onto the islands from elsewhere [31, 54, 66]. However, one difficulty in this scenario is the recent analysis of the mtDNA of extant wild pigs which showed that the current Ryukyu wild pig population (*Sus scrofa ryukyuanus*) is a unique, endemic species of the Ryukyu Islands. It was separated from the Eurasian wild pig populations much earlier than the human arrival, probably during the middle Pleistocene [67]. Another difficulty is an ancient DNA study of wild pigs from Holocene archeological sites which suggests the possible translocation of pigs by Holocene prehistoric people [68]. We do not know the genetic relation between the Paleolithic and modern wild pig population of the Ryukyus, and how the Holocene prehistoric translocation of pigs affected the genetic traits of the Ryukyu wild pigs. Therefore, the details of when and how the endemic Ryukyu wild pigs were distrib-

Paleolithic people immigrated to the Ryukyu Islands more than 36,000 years ago. Morphological and genetic studies of Paleolithic human fossils from this area have indicated that they probably came through Southeast Asia in the course of the worldwide dispersal of early modern humans. The common use of shell tools including fishhooks and the remarkable consumption of aquatic resources as foods

However, Paleolithic Okinawan culture was unique in dominance of marine shell artifacts and biased consumption of freshwater animals. This unique lifestyle adapted to the stone-poor and shell-rich environment of the island, where there were limited terrestrial animals. The adaptive lifestyle on Okinawa, which is a relatively small oceanic island, suggests the plasticity of Paleolithic people's behavior. Their behavioral plasticity may be one of the driving forces that enabled *Homo* 

*DOI: http://dx.doi.org/10.5772/intechopen.92391*

**Figure 5.** *Terrestrial and freshwater animals of Okinawa Island.*

#### *The Migration, Culture, and Lifestyle of the Paleolithic Ryukyu Islanders DOI: http://dx.doi.org/10.5772/intechopen.92391*

activity. The exploitation of variety of marine resources may be one of the factors that enabled Paleolithic migration to the variety of islands. As indicated by the studies on human remains and shell artifacts, relation between Okinawa and ISEA is suggested again in the viewpoint of aquatic resource usage. However, dominance of the freshwater animals is the unique point of Paleolithic Okinawa. One reason may be the limited terrestrial animals, and another reason may be seasonality. The oxygen isotope study on freshwater snails indicated that these freshwater animals were consumed mainly in autumn [16]. Paleolithic people of Okinawa may have used more marine resources in other seasons, though we do not have any evidence at present.

Another notable behavior of Paleolithic Ryukyu Islanders is the possible translocation of wild pigs earlier than 20,000 years ago. Researchers have reported that the Pleistocene translocation of animals occurred in Cyprus around 11,000 years ago [63] and Manus Island around 13,000 years ago [64]. In the case of the Ryukyu Islands, after the extinction of the endemic deer between 30,000 and 35,000 years ago, wild pigs appeared and increased in number around 20,000 to 27,000 years ago [31, 39, 54, 65]. Because Okinawa Island was isolated from the Eurasia continent, mainland Japan, and the remaining Ryukyu Islands during the Pleistocene [27], the increase in the wild pig population might have resulted from people translocating pigs onto the islands from elsewhere [31, 54, 66]. However, one difficulty in this scenario is the recent analysis of the mtDNA of extant wild pigs which showed that the current Ryukyu wild pig population (*Sus scrofa ryukyuanus*) is a unique, endemic species of the Ryukyu Islands. It was separated from the Eurasian wild pig populations much earlier than the human arrival, probably during the middle Pleistocene [67]. Another difficulty is an ancient DNA study of wild pigs from Holocene archeological sites which suggests the possible translocation of pigs by Holocene prehistoric people [68]. We do not know the genetic relation between the Paleolithic and modern wild pig population of the Ryukyus, and how the Holocene prehistoric translocation of pigs affected the genetic traits of the Ryukyu wild pigs. Therefore, the details of when and how the endemic Ryukyu wild pigs were distributed throughout the Ryukyu Islands remain controversial.
