Searching the island of Flores for archaeological evidence of the passage of Australia's Aboriginal ancestors
For the last 10 years Dr. Mike Morwood and his colleagues have been searching the island of Flores for archaeological evidence of the passage of Australia's Aboriginal ancestors as they passed along the Indonesian chain of islands towards the sub-continent where they arrived about 60,000 years ago, some 14,500 years after the super volcano eruption of Mt Toba on the island of Sumatra that annihilated the Homo sapiens inhabitants of India Peopling the World and plunged the world into a six year long winter followed by a 1,000 year long mini Ice Age.
Flores lies towards the eastern end of the chain of islands that make up Indonesia. As can been seen in the map below it is east of the Wallace Line that runs between Lombok and Bali and therefore was always separated from Asia by comparatively wide channels of sea water.
Morwood has failed to find evidence on the island of Homo sapiens earlier than 11,000 years ago, although he has found crude stone tools that show Homo erectus was there 840,000 years ago. Not only did Erectus manage to cross the Wallace line, but also a type of Elephant called Stegodons, similar to Mastodons. Elephants are good swimmers because they are so buoyant, so presumably Stegodons swam across from Bali via Lombok and Sumbawa to Flores. How Erectus made the sea crossing is an unanswered question, but they did because they left tools behind to prove it.
A giant carnivorous lizard, similar to but larger than the ones that now live on Komodo island, also reached Flores. Australian goannas are good swimmers so probably the lizards came from the east and are related to the super giants species that inhabited Australia until 40,000 years ago when they were exterminated by Homo sapiens, along with all the other megafauna like the two ton marsupial diprotodons, an elephant sized wombat, along with the meat eating kangaroos.
|What has rocked the scientific world is that the bones found show Floresiensis to be a dwarf, small brained hominin, just over three feet high. According to the scientific reports released so far the bones of six individuals are those of the Homo group that includes Homo sapiens and have been dated at between 95,000 and 13,000 years old.
The cave is named Liang Bua and is situated in the middle of the western end of the island.
There are still ten active volcanoes in the centre and eastern sections of Flores and Liang Bua does have volcanic ash deposits dated at 12,000 years ago so volcanic activity might be the cause of the extinction of Floresiensis and the elephants. The island is 8,870 square miles in area, 224 miles long and 37 miles wide, which makes it slightly larger than Wales, or 1/6 the size of Florida. It is very mountainous with peaks reaching 7,000 feet, and is heavily forested with jungle that includes coconut palms. There are no navigable rivers except the Reo that only reaches one mile inland. It is tropical with an average rainfall of 46 inches and a mean temperature of 77 to 80 degrees. Most of the interior of the island is unexplored.
The present occupants of the island are of a Papuan type, although there is a strong Chinese influence from shipwreck survivors. When the island was colonised by the Dutch in the 16th century they repeatedly heard stories of Little People having been seen in the jungle from the indigenous Homo sapiens Ngadha and Manggarai tribes, but none of these rumours appear to have been proven.
The limestone cave overlooks a river, is 1,500 feet above sea level and situated in the heart of the western end of the island. The cave was formed as an underground cavern whose northern end was exposed by the river that now lies 600 feet away and 90 feet below. Five river terraces at different elevations in the valley indicate a complex process of erosion over a very long period of time.
The best-preserved bones are those of a female dated at 18,000 years old and are not yet fossilised, and the scientists hope that they are young enough to contain extractable DNA. 'Flo', as she is called, was discovered 20 feet below the present surface in dark-brown silt covered by wash sediments and tuffaceous silt derived from volcanic eruptions. There was no evidence of deliberate burial, but the body indicates fine sediments rapidly buried it soon after death, when still partially fleshed. In comparison with adult Homo erectus skulls Floresiensis is extremely small. The volume of the skull is 380 cubic cm, well below Homo erectus at 900 to 1100 cubic cm, or the previously accepted range for the genus Homo, but equal to the minimum estimates for Australopithecus. On the other hand the cranial vault bone is thick and lies within the range of Home erectus and Homo sapiens. Flo had a lean and narrow body shape typical of tropical modern humans and weighed around 30 lbs.
Among modern humans, populations of extremely small average stature were historically found in predominately rainforest habitat in equatorial zones of Africa, Asia, Melanesia, including the Barrinean pygmies of Queensland's rainforests. The difference between Flo and these other pygmies is that she has a greatly reduced skull size. The location of Homo Floresiensis makes it far more likely that they are the end product of a long period of evolution on a comparatively small island, where environmental conditions placed small body size at a selective advantage. Insular dwarfing, in response to the specific ecological conditions that are found on small islands, such as Malta, is well documented for animals larger than a rabbit.
There are two possibilities concerning the first hominin immigrants to Flores 840,000 years ago. One, they may have had a similar body size to Homo erectus, or two, they are an unknown small-bodied and small-brained hominin that arrived from the Sunda Shelf. It is possible that the evolutionary history of Homo floresiensis is unique, but Dr Morwood and his colleagues consider it more likely that, following the dispersal of Homo erectus out of Africa, there arose a much greater variation in morphological attributes of this genus than has been previously thought, and therefore one of the last members of a long standing population that had evolved to dwarf size at least 95,000 years ago, from normal Homo erectus ancestors.
Found with Flo in the cave were small faunal remains including fish, frog, snake, tortoise, birds, and bats. Middle size faunal remains include giant rats that she may have hunted. Large faunal remains include Komodo dragon and 17 juvenile elephants with some of their bones charred, possibly indicating that Flo was able to control fire. Only thirty-two artefacts were found around Flo, but in another area of the cave at the same level 5,000 volcanic or chert artefacts per cubic yard were recovered. With the elephant bones were found points, blades and microblades that could be barbs that were fixed to a wooden shaft. The finds suggest that Flo and her people were selectively hunting juvenile elephants. All traces of elephants disappear above the 12,000 year level of tuffaceous silts derived from volcanic eruptions that coincide with the probable extinction of Homo Floresiensis.
Homo sapiens could have arrived on the island around 70,000 years ago if they were to reach Australia by 65,000 years ago, but no modern man artefacts have yet been found. The one heavy percussion artefact discovered in the Liang Bua cave was found at the 102,000 year old level. The 800,000 year old artefacts found by Morwood on Flores are similar to those of Javanese Homo erectus.
Is Homo floresiensis a dwarf Homo erectus, the product of local evolution that has taken place over a period of at least 840,000 years in a confined habitat?