Rusinga Island, with an elongated shape approximately 10 miles (16 km) from end to end and 3 miles (5 km) at its widest point, lies in the eastern part of

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after ...

at the mouth of the Winam Gulf. Part of Kenya, it is linked to Mbita Point on the mainland by a

causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet Tra ...

Demography

The local language is Luo, although the ancestors of the current inhabitants were Suba people who came in boats several hundred years ago from Uganda as refugees from a dynastic war. Many Rusinga place names portray Suba origins, including the island's name itself and its central peak, Lunene. There was an extinct language of Uganda called Singa, alternatives Lusinga and Lisinga, spoken only on Rusinga Island (which, of course is in Kenya). It belonged to the same group of Niger–Congo as Suba. As of 2006, estimates of Rusinga's population range between 20,000 and 30,000. The entire island is part of the Homa Bay County. Most residents of Rusinga make their living from subsistence agriculture (maize and millet), as well as fishing. The native tilapia is still caught, though this species (like all others native to the lake) has been decimated by the voracious Nile perch that was introduced into the lake in 1954. Constant onshore winds cool the lakeward side of the island and provide clean beaches with ideal swimming and boating conditions, but poor roads between Rusinga and the nearest town, Homa Bay, inhibit trade and tourism. The brightly glittering black sands of the beaches are made of crystals of melanite garnet, barkevikite hornblende, and magnetite eroded from the uncompahgrite lava fragments in the

agglomerate Agglomerate (from the Latin ''agglomerare'' meaning "to form into a ball") is a coarse accumulation of large blocks of volcanic material that contains at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records flui ...

s that overlie the fossil beds. The island is also notable as the family home and burial site of Tom Mboya, who before his assassination in 1969 was widely pegged as

Jomo Kenyatta Jomo Kenyatta (22 August 1978) was a Kenyan anti-colonial activist and politician who governed Kenya as its Prime Minister from 1963 to 1964 and then as its first President from 1964 to his death in 1978. He was the country's first indigenous ...

's successor as President of the new nation of Kenya.

Palaeontology

Rusinga is widely known for its extraordinarily rich and important fossil beds of extinct Miocene mammals, dated to 18 million years. The island had been only cursorily explored until the Leakey expedition of 1947-1948 began systematic searches and excavations, which have continued sporadically since then. The end of 1948 saw the collection of about 15,000 fossils from the Miocene, including 64

primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

called by

Louis Leakey Louis Seymour Bazett Leakey (7 August 1903 – 1 October 1972) was a Kenyan-British palaeoanthropologist and archaeologist whose work was important in demonstrating that humans evolved in Africa, particularly through discoveries made at Olduvai ...

"Miocene apes." All the species of '' Proconsul'' were among the 64 and all were given the name ''africanus'', although many were reclassified into ''nyanzae'', ''major'' and ''heseloni'' later. Mary Leakey discovered the first complete skull of Proconsul, then considered a "stem hominoid", in 1948. Excavation of the fossil was completed by Louis' assistant, Heselon Mukiri (whence Walker's 1993 name heseloni). Many thousands of fossils are now known from five major sites, with abundant hominoids including an almost complete skeleton of a second species of ''Proconsul'', as well as ''Nyanzapithecus'', ''Limnopithecus'', ''Dendropithecus'' and ''Micropithecus'', all of which show arboreal rather than terrestrial adaptations. The first true

monkeys Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, which constitutes an incomple ...

do not appear until around 15 million years ago, so it is widely supposed that the diverse Early Miocene African catarrhines like those found on Rusinga filled that adaptive niche. The phylogenetic position of these primates has been debated. It has been theorized that ''Proconsul'' is a stem catarrhine and therefore ancestral to both Cercopithecids (Old World monkeys) and hominids (great apes and humans), rather than a stem hominoid.

', Harrison T. 1987. "The phylogenetic relationships of the early catarrhine primates: a review of the current evidence." ''Journal of Human Evolution'' 16(1), 41-80 Pleistocene mammal fossils, including an extinct

antelope The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia. Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...

called

Rusingoryx ''Rusingoryx'' is a genus of extinct alcelaphine bovid artiodactyl closely related to the wildebeest. It contains only one species, ''R. atopocranion'', that lived on the plains of Kenya during the Pleistocene. It was originally named as a speci ...

, notable for its nasal dome hypothesised to produce loud calls, known nowhere else, are also common in former shoreline deposits around the edges of the island, left behind as Lake Victoria has slowly subsided over the centuries due to erosion in its outlet.

Geology

The fossil beds are layers of volcanic ash produced by a succession of explosive eruptions during the earliest stages of a volcano that eventually covered an area 75 miles in diameter. The volcano is now eroded down to the frozen magma in its vent that makes up the Kisingiri hills on the mainland opposite Rusinga, and the surrounding remnants of the cone: the semicircular Rangwa mountain range, and the islands of Rusinga and neighboring Mfangano Island. This rift valley volcano on the southern flank of the now-inactive Winam Gulf tapped much deeper in the mantle than oceanic or

subduction zone Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

volcanos, and its lavas and explosive ash clouds thus contained much more carbonate and alkali than normal. This meant that even though the Miocene environment was a tropical rainforest, the chemistry of the successive ash beds was that of a desert dry lake, preserving everything from caterpillars and berries to apes and elephants in an unusual situation found only in a few other East African volcanos, notably

Menengai Menengai Crater is a massive shield volcano with one of the biggest calderas in the world, in the Great Rift Valley, Kenya. It is the largest volcano caldera in Kenya and the second largest volcano caldera in Africa. Volcanic formed rich loam so ...

and Homa Mountain in western Kenya,

Napak Napak is a town in Northern Uganda. It is the commercial, administrative and municipal headquarters of Napak District. The district is named after the town. Location The town is situated approximately , southwest of Moroto, the largest town in K ...

and

Mount Elgon Mount Elgon is an extinct shield volcano on the border of Uganda and Kenya, north of Kisumu and west of Kitale. The mountain's highest point, named "Wagagai", is located entirely within Uganda.

in Uganda, and the much younger Ol Doinyo Lengai in Tanzania, which created the fossil beds of

Olduvai Gorge The Olduvai Gorge or Oldupai Gorge in Tanzania is one of the most important paleoanthropology, paleoanthropological localities in the world; the many sites exposed by the gorge have proven invaluable in furthering understanding of early human ev ...

Notes

External links

GEF RUSINGA ISLAND Projects
United Nations Development Programmes.
Greening Rusinga Island
Africa Now site. *
Palaeoenvironments of Early Miocene Kisingiri volcano Proconsul sites: Evidence from carbon isotopes, palaeosols and hydromagmatic deposits
', article by Erick Bestland and Evelyn S. Krull, ''Journal of the Geological Society'', September, 1999. An extensive abstract of this highly technical article is displayed at no charge.
Living Waters Intl
Since 2006, Living Waters Intl, a faith based non-profit organization, has been providing clean water, medical care, a feeding center, orphan assistance and educational facility upgrades, sustainable vegetable gardens, to the people of Rusinga Island, Kenya, Africa {{Coord, 0, 24, S, 34, 10, E, region:KE_type:isle, display=title Homa Bay County Islands of Lake Victoria Lake islands of Kenya Miocene paleontological sites of Africa

Demography

Palaeontology

Geology

See also

Notes

External links