10th millennium BC in the context of "Palaeolithic"

Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, sharing a maritime border with Ecuador to the south of Cocos Island. It has a population of around five million in a land area of nearly 51,180 km (19,760 sq mi); the capital and largest city is San José, home to around 350,000 residents and two million people in the surrounding metropolitan area.

Humans have been present in Costa Rica since between 7,000 and 10,000 BC. Various indigenous peoples lived in the territory before it was colonized by Spain in the 16th century. Costa Rica was a peripheral colony of the Spanish Empire until independence in 1821 as part of the First Mexican Empire, followed by membership in the Federal Republic of Central America in 1823, from which it formally declared independence in 1847. The country underwent gradual modernization under relatively stable authoritarian rule until the late 19th century, when it promulgated a liberal constitution and held the first free and fair national election in Central America.

The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as the time between c. 129,000 and c. 11,700 years ago. The late Pleistocene equates to the proposed Tarantian Age of the geologic time scale, preceded by the officially ratified Chibanian (commonly known as the Middle Pleistocene). The beginning of the Late Pleistocene is the transition between the end of the Penultimate Glacial Period and the beginning of the Last Interglacial around 130,000 years ago (corresponding with the beginning of Marine Isotope Stage 5). The Late Pleistocene ends with the termination of the Younger Dryas, some 11,700 years ago when the Holocene Epoch began.

The term Upper Pleistocene is currently in use as a provisional or "quasi-formal" designation by the International Union of Geological Sciences (IUGS). Although the three oldest ages of the Pleistocene (the Gelasian, the Calabrian and the Chibanian) have been officially defined, the late Pleistocene has yet to be formally defined.

The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time between 2.580 ± 0.005 Ma (million years ago) and 0.773 ± 0.005 Ma. The term Early Pleistocene applies to both the Gelasian Age and the Calabrian Age.

While the Gelasian and the Calabrian have officially been defined by the International Union of Geological Sciences (IUGS) to effectively constitute the Early Pleistocene, the succeeding Chibanian and Tarantian ages have yet to be ratified. These proposed ages are unofficially termed the Middle Pleistocene and Late Pleistocene respectively. The Chibanian provisionally spans time from 773 ka to 126 ka, and the Tarantian from then until the definitive end of the whole Pleistocene, c. 9700 BC in the 10th millennium BC.

A boomerang (/ˈbuːməræŋ/) is a thrown tool typically constructed with airfoil sections and designed to spin about an axis perpendicular to the direction of its flight, designed to return to the thrower. The origin of the word is from an Aboriginal Australian language of the Sydney region. Its original meaning, which is preserved in official competitions, refers only to returning objects, not to throwing sticks, which were also used for hunting by various peoples both in Australia and around the world. However, the term "non-returning boomerang" is also in general use. Various forms of boomerang-like designs were traditionally and in some cases are still used by some groups of Aboriginal Australians for hunting. The tools were known by various names in the many Aboriginal languages prior to colonisation. The oldest surviving Aboriginal boomerang, now held in the South Australian Museum, was found in a peat bog in South Australia, dated to 10,000 BC. Historically, boomerangs have been used for hunting, sport, and entertainment, and are made in various shapes and sizes to suit different purposes. Ancient "boomerangs", used for hunting, have also been discovered in Egypt, the Americas, and Europe, although it is unclear whether any of these were of the returning type.