There are two very different theories regarding the origins of modern Southeast Asians. The viewpoints about the origins of these peoples are entangled with the wider debate regarding the origins of all modern humans.
- The generally accepted theory, based on the 'Out of Africa' model, is that modern humans migrated from Africa and across to Asia about 50-70,000 years ago. The first Asian people, represented by the skulls from the Upper Cave at Zhoukoudian in China, more closely resemble contemporary Africans and Europeans than they do modern Asians.
- Some scientists believe that Southeast Asians are the direct descendants of Homo erectus that migrated from Africa and across to Asia about 1.8 million years ago. The physical features typical of modern Asians can thus be traced back to Homo erectus specimens such as Dali and Peking Man. The Dali skull plays a crucial part in the Multiregional model of human origins and hence of Southeast Asians. The adult male skull found in the Shaanxi Province in China in 1978, is classified as Homo sp (species uncertain). It is dated to 200,000 years. It is claimed by some that its more modern features provide a link between the older Homo erectus specimens from Zhoukoudian Locality 1 and the modern Chinese. However, most others dispute this because it lacks modern Asian facial characteristics.
The Southeast Asian fossil record
The fossil record is poor for dates from about 100,000 years ago to about 25,000 years ago - a key time span for the a presumed arrival, or evolution, of modern humans in this region. There are few to no archaeological sites or fossils in which provenance and date are securely established.
One possible exception is a skeleton recovered in 2003 from the Tianyuan Cave, Zhoukoudian, near Beijing City. It dates to 42,000 to 38,500 years ago, making it the oldest securely dated modern human skeleton in China and one of the oldest modern human fossils in eastern Eurasia. The specimen is a modern human, but it does have a few archaic characteristics, particularly in the teeth and hand bones. The discoverers believe this has implications regarding the spread of modern humans from Africa, suggesting that this may not be as simple as first thought and may involve more than one migration event.
The fossil record after 25,000 years ago is better represented and more securely dated, providing more opportunities to examine remains and make inferences about modern humans origins in this area.
The appearance of Southeast Asian features
Early humans in Asia lack the characteristic features of the skull and face that are found in modern Southeast Asians. Exactly when typical Southeast Asian features arose is difficult to ascertain, but there appears to be little evolutionary continuity between these modern Asians and the ancient populations that lived in Southeast Asia before 15,000 years ago.
Typical modern Southeast Asian physical characteristics include:
- an upward orientation of the cheek bones
- a broad face with limited projection
- flattened nasal bones and a broad nose
- shovel-shaped incisors
The earliest evidence of these Asian features in the fossil record is found in skulls from Baoji and Huaxian in China, dated to about 7,000 years old. Genetic studies support the recent origin of Asian features. They suggest that a significant population reduction occurred in Asia about 10,000 years ago. This was followed by a rapid expansion, linked with the spread of agriculture, of a population where Asian features were dominant.
Key early specimens that lack modern Southeast features:
- Liujiang skull, from the Guanxi province, South China. The remains of a middle-aged man found in a cave in 1958. The age is unknown but its similarities to Zhoukoudian 101 suggest a date of 25,000 to 10,000 years.
- Zhoukoudian skull from Upper Cave 101, China. Found in 1933 with 2 other skulls and bones from about 8 individuals. The inclusion of grave goods such as red ochre, body ornaments, bone implements and stone artefacts suggests a ritualistic burial. Dated to between 25,000 and 10,000 years.
- Minatogowa 1 skull from Japan. Male skeleton found in 1970. It shares more traits with the skull from Liujiang than is does with Neolithic and modern Asians. Dated to 17,000 years.
The first modern Indonesians
The Indonesian fossil record was once argued to provide evidence for a regional or localised evolution. A direct line of descent was claimed from Homo erectus people such as Java Man through to modern Indonesians and also to Indigenous Australians. The first humans to colonise Indonesia and Australia probably had their origins in a more recent movement of Homo sapiens through the Indonesian archipelago.
Attempts to prove this evolutionary continuity have been unsuccessful to date. The fossil record is fragmentary and the sample is limited for crucial periods such as that from 100,000 to 50,000 years ago. Many Indonesian fossils were found and extracted by locals without recording the exact location. This makes it almost impossible to create a well-dated fossil sequence. The anatomical features, which are supposed to demonstrate an evolutionary sequence, are also the subject of dispute.
- Solo Man skullcap from Ngangdong. This skulcap shares similarities with earlier Homo erectus specimens from Sangiran and is considered to be a late Homo erectus. Age is uncertain and, because its exact location is unknown, published dates have ranged from 50,000 to 500,000 years.
- Wadjak skull from Java. This is a Homo sapiens skull discovered in 1889 but not described until 1921. Its age is uncertain but it is probably less than 20,000 years old and may be as young as 8,000. The lack of certainty regarding Wadjak’s age and its relationship to other ancient remains reduces the importance of this specimen in discussions of Asian and Australian migrations.
- Java Man (Trinil 2) from Trinil, Java. This is the Homo erectus skull cap discovered by Dubois in 1891 and dated to 500,000 years.