REVIEWS for two independent migrations, one towards Taiwa and the other towards Polynesia. The latter would have occurred through island Southeast Asia, which was by far the fastest and widest expansion of humans during rehistoric times. The Austronesian languages of the Pacific spread across 10,000 kilometres of coastline and sea within a span of only 1, 500 years Interestingly, a repeated analysis of the published mtdna data by richards et al. is more in line with the hypothesis based on the Y-chromosome data8 The genetic relationship between East Asians (including Austronesian-speaking Pacific Islanders)and Australoids still remains a question. However, data from both y chromosomes and autosomes have indicated eparate migrations from Africa, one to East and the other to oceania 4.36, 0 Conclusions Figure 3 The putative migratory routes of East Asians On the basis of the genetic evidence generated so far of African origin. Migrations that have occurred in the past particularly from Y-chromosome data, modern humans 60,000 years are indicated by the red arrows. The first entry in East Asia have a recent common origin in Africa. It is of modern humans into the southern part of East Asia suggested that the first entry of modern humans into occurred about 18,.000-60,000 years ago, followed by a the southern part of East Asia occurred about northward migration. A southern route also started from 18,000-60,000 years ago, and was followed by a north mainland Southeast Asia, through Malaysia and Indonesia. eventually continuing eastwards to the Pacific lslands. The ward migration that coincided with the receding glaci- blue arrows indicate a contribution from Central Asia that ers in that area. a southern route also started from arrived in East Asia at a later time mainland Southeast Asia, through Malaysia and Indonesia, eventually continuing eastwards to the 6》 Animated online Pacific Islands(FIG 3). It should be noted that the con- clusions made on the East Asian-specific haplotypes. The dominating Y- humans in East Asia are definitely not the end of the A hypothesis that claims a rapid chromosome haplotypes found in the Pacific story. Many questions are unresolved. Future studies slanders, including Polynesians and Micronesians, will be directed towards: revealing any genetic contribu- constitute a small subset of haplotypes found in tion from local populations by studying a larger sample and the associated outheast Asian populations. More interestingly, the of East Asians; delineating the local migratory routes in aplotypes found in Taiwanese aborigines are general- East Asia that led to the diversified languages spoken in Pacific islands about 4,000 to ly absent in Polynesia, whereas a specific type found in this area( six language families and almost 2,000 indi 5,000 years ago. Melanesian populations(H17) is also missing in the vidual languages, see LINKs); evaluating the genetic influ- Polynesian populations. These findings are contrary to ce of Central Asia on East Asian populations, such as the two prevailing hypotheses of Polynesian origins. YAP*and M89T: and reconstructing migratory routes First, it negates the Taiwan-homeland theory of from East Asia to the New World implicated by the Polynesian origin that is based on mtDNA studies -3. CT transitions at the RPS4Y locus. Finally, we should The Y-chromosome data, however, do not entirely assess the relationship between East Asians and refute the EXPRESS TRAIN MODEL, which contends the Australoids. Resolving these questions will lead to a spread of Austronesian language and Lapita culture more complete understanding of the evolutionary his- rom Southeast Asia5. Second, the Y-chromosome tory of our own species. data challenge the Melanesian origin of the Pacific Islanders that is supported by a-globin data.57. Links Interestingly, all of the Y haplotypes found in Taiwan DATABASE LINKS MXI and in Polynesia were detected in the mainland FURTHER INFORMATION The Ethnologue: Languages of Southeast Asian populations. These findings have led the World to an alternative model for the origins of Polynesians, ENCYCLOPEDIA OF LIFE SCIENCEs Human evolution: in which Southeast Asia provided the genetic source Overview 1. Cann, R L, Stoneking. M.& wilson, ochondrial 03-150701991) igrs. Science271.1380-138701996) 2. Stringer, C B. Andrews, P c-e 32 cock, A M. ef a. High resolution of hur evidence lutionary trees with polymorphic microsatellites. China. Proc. Naf Acad. Sci. USA 95.11763-11768 origin of modern humans. Science 239. 263-126801988 try for human Y ntana-Murci, L. et al. Genetic evidence of an early populations and the disequilibrium at the CD4 locus and modern human 32 NOVEMBER 2000 VOLUME 1 Nnature. com/reviews/genetics M@ 2000 Macmillan Magazines Ltd132 | NOVEMBER 2000 | VOLUME 1 www.nature.com/reviews/genetics REVIEWS for two independent migrations, one towards Taiwan and the other towards Polynesia. The latter would have occurred through island Southeast Asia, which was by far the fastest and widest expansion of humans during prehistoric times. The Austronesian languages of the Pacific spread across 10,000 kilometres of coastline and sea within a span of only 1,500 years51. Interestingly, a repeated analysis of the published mtDNA data by Richards et al. is more in line with the hypothesis based on the Y-chromosome data58. The genetic relationship between East Asians (including Austronesian-speaking Pacific Islanders) and Australoids still remains a question. However, data from both Y chromosomes and autosomes have indicated two separate migrations from Africa, one to East Asia and the other to Oceania34,36,40. Conclusions On the basis of the genetic evidence generated so far, particularly from Y-chromosome data, modern humans in East Asia have a recent common origin in Africa. It is suggested that the first entry of modern humans into the southern part of East Asia occurred about 18,000–60,000 years ago, and was followed by a north￾ward migration that coincided with the receding glaci￾ers in that area. A southern route also started from mainland Southeast Asia, through Malaysia and Indonesia, eventually continuing eastwards to the Pacific Islands (FIG. 3). It should be noted that the con￾clusions made on the origin and migrations of modern humans in East Asia are definitely not the end of the story. Many questions are unresolved. Future studies will be directed towards: revealing any genetic contribu￾tion from local populations by studying a larger sample of East Asians; delineating the local migratory routes in East Asia that led to the diversified languages spoken in this area (six language families and almost 2,000 indi￾vidual languages, see LINKS); evaluating the genetic influ￾ence of Central Asia on East Asian populations, such as YAP+ and M89T; and reconstructing migratory routes from East Asia to the New World implicated by the C→T transitions at the RPS4Y locus. Finally, we should assess the relationship between East Asians and Australoids. Resolving these questions will lead to a more complete understanding of the evolutionary his￾tory of our own species. East Asian-specific haplotypes. The dominating Y￾chromosome haplotypes found in the Pacific Islanders, including Polynesians and Micronesians, constitute a small subset of haplotypes found in Southeast Asian populations. More interestingly, the haplotypes found in Taiwanese aborigines are general￾ly absent in Polynesia, whereas a specific type found in Melanesian populations (H17) is also missing in the Polynesian populations. These findings are contrary to the two prevailing hypotheses of Polynesian origins. First, it negates the Taiwan-homeland theory of Polynesian origin that is based on mtDNA studies50–53. The Y-chromosome data, however, do not entirely refute the EXPRESS TRAIN MODEL, which contends the spread of Austronesian language and Lapita culture from Southeast Asia54,55. Second, the Y-chromosome data challenge the Melanesian origin of the Pacific Islanders that is supported by α-globin data56,57. Interestingly, all of the Y haplotypes found in Taiwan and in Polynesia were detected in the mainland Southeast Asian populations. These findings have led to an alternative model for the origins of Polynesians, in which Southeast Asia provided the genetic source Figure 3 | The putative migratory routes of East Asians of African origin. Migrations that have occurred in the past 60,000 years are indicated by the red arrows. The first entry of modern humans into the southern part of East Asia occurred about 18,000–60,000 years ago, followed by a northward migration. A southern route also started from mainland Southeast Asia, through Malaysia and Indonesia, eventually continuing eastwards to the Pacific Islands. The blue arrows indicate a contribution from Central Asia that arrived in East Asia at a later time. Animated online EXPRESS TRAIN MODEL A hypothesis that claims a rapid eastward migration of humans starting in Southern China, spreading Austronesian language and the associated Lapita culture through the Pacific islands about 4,000 to 5,000 years ago. Links DATABASE LINKS MX1 FURTHER INFORMATION The Ethnologue: Languages of the World ENCYCLOPEDIA OF LIFE SCIENCES Human evolution: Overview 1. Cann, R. L., Stoneking, M. & Wilson, A. C. Mitochondrial DNA and human evolution. Nature 325, 31–36 (1987). 2. Stringer, C. B. & Andrews, P. Genetic and fossil evidence for the origin of modern humans. Science 239, 1263–1268 (1988). 3. Vigilant, L., Stoneking, M., Harpenden, H., Hawkes, K. & Wilson, A. C. African populations and the evolution of human mitochondrial DNA. Science 253, 1503–1507 (1991). 4. Bowcock, A. M. et al. High resolution of human evolutionary trees with polymorphic microsatellites. Nature 368, 455–457 (1994). 5. Hammer, M. F. A recent common ancestry for human Y chromosomes. Nature 378, 376–378 (1995). 6. Tishkoff, S. A. et al. Global patterns of linkage disequilibrium at the CD4 locus and modern human origins. Science 271, 1380–1387 (1996). 7. Chu, J. Y. et al. Genetic relationship of populations in China. Proc. Natl Acad. Sci. USA 95,11763–11768 (1998). 8. Quintana-Murci, L. et al. Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa. Nature Genet. 23, 437–441 (1999). 9. Wilson, A. C. & Cann, R. L. The recent African genesis of © 2000 Macmillan Magazines Ltd