During the Pleistocene (approximately 1.75 million years ago to 10,000 B.C.), the lowering and rising of the world's sea levels have left the Philippine Islands alternately connected to and isolated from the nearby islands and via them to the mainland of Southeast Asia. Although some scientists claim to find stone tools made by Homo erectus as early as 500,000 B.C., most scholars believe that the first humans to move into the Philippines are Homo sapiens who come no earlier than about 38,000 B.C. For many thousands of years, these first Filipinos probably live somewhat isolated, their basic culture that of the hunters-gatherers and stone tools of this period. Then, starting about 3000–2800 B.C., new migrants begin to link the Philippines with developments in East and Southeast Asia, and the Philippines participate in the evolving cultural phases of Southeast Asia—the Neolithic, Bronze Age, and eventually the Iron Age. However, the first written references to the Philippines are not found until the eighth century A.D. and the coming of the first Chinese and Japanese.
38,000–28,000B.C.: People regarded as the ancestors of the present-day Negritos move into the Philippines. (It is assumed that they walk across land bridges from the southwest, accessible due to the low sea level.) Their exact origin is not known, but these people are distinguished by their relatively short stature, dark skin, and tightly curled hair; they are probably related to the peoples who are also settling the Melanesian Islands in this era. (The Negritos still live in coastal and inland locales in parts of the Philippines where they include such tribes as the Aeta; their most immediate modern relatives seem to be the Negritos of peninsular Malaysia.)
28,000–3000B.C.: The inhabitants of the Philippines probably do not differ much from the peoples and cultures elsewhere in Southeast and East Asia (although when the sea rises to its present level, between about 13,000 and 6000 B.C., the islands are physically isolated). They are primarily hunters, fishers, and food-foragers, with little material culture beyond their flaked stone tools; they