Turning evolution upside down
In the study of human evolution, Australia has not traditionally believed to have much to offer; however, the skeletal record has thrown up a few spanners in the works that may one day transform beliefs about where humans came from.
One of these spanners is Mungo Man, who was discovered in 1974 in the dry lake bed of Lake Mungo in west NSW. Mungo Man
was a hominin who was estimated to have died 62,000 years ago and was ritually buried with
his hands covering his penis. Anatomically, Mungo
Man's bones were distinct from other human skeletons being unearthed in Australia.
Unlike the younger skeletons that had big-brows and thick-skulls, Mungo Man's skeleton
was finer, and more like modern humans.
The ANU's John Curtin School of Medical Research found that Mungo Man's skeleton's
contained a small section of mitochondrial DNA. After analysing the DNA, the school
found that Mungo Man's DNA bore no similarity to the other ancient skeletons,
modern Aborigines and modern Europeans. Furthermore, his mitochondrial DNA had become extinct. The results called into
question the 'Out of Africa' theory of human evolution. If Mungo Man was descended
from a person who had left Africa in the past 200,000 years, then his mitochondrial
DNA should have looked like all of the other samples.
Another spanner in the traditional theories are the Kow Swamp skeletons from northern Victoria, which are reminiscent of Homo erectus. Specifically, they have thick brow ridges, sloping foreheads and very large teeth. If the Kow Swamp skeletons had been found in Indonesia and dated at 100,000 + years, then they might have been categorised as Homo erectus but being found in Australia and dated at only 10,000 years was problematic. According to traditional theories, Homo erectus never reached Australia and was believed to have died out when Homo sapiens reached Indonesia in excess of 50,000 years ago. Even if the Kow Swamp people weren't Homo erectus, it was hard to explain why an ancient looking people occupied Australia after a more modern looking people. As explained by Professor Alan Thorne,
"The Kow Swamp people have thick brow ridges, very large faces and the biggest teeth that have ever existed in modern humans. And that creates a problem. They look ancient but at 10,000 years of age they’re much younger than the lightly built Mungo people. How could that be?"
One academic, Dr Tim Stone from the University of Melbourne, tried to argue the unusual skeletal shapes were the result of some kind of localised adaptation to the cold. (1) Stone basically argued that the Homo sapiens of the area evolved to look like Homo erectus because the body shape was better suited to the climate. In Stone's view, no other Australian population groups looked like them because the Kow Swamp people became geographically isolated for tens of thousands of years.
Stone's argument was an illogical considering that Kow Swamp was on a relatively flat area of land near the Murray River, which would likely attract high volumes of human traffic. As a point of comparison, a small population of humans in Tasmania were genetically isolated for at least 10,000 years in a very cold climate. Although paintings and photos show a slight divergence from some mainland Aborigines, their skeletons and features looked very similar to modern gracile humans.
Tasmanian Aborigines looked a lot like Africans but despite being isolated for perhaps 10,000 years in a cold climate, they still looked like modern humans.
Other academics have argued that the unusual head shapes of the Kow Swamp people were the result of cranial modification (3). In other parts of the world, this occurs due to mothers wrapping cloth around their infants' heads.
Like Stone's theory of climatic adaption, this was also an illogical explanation as body modification of infants tends to be a feature of agricultural societies that have developed hierarchical systems of status. Furthermore, it usually requires cloth to place sustained pressure on the child's skull and there is no evidence of weaving amongst Aborigines. Admittedly, it had been observed in Cape York where an adult pushed on the infants forehead using their hands to flatten the face, but it was extremely rare.
One academic defending the orthodox position, Dr Colin Groves, didn't even bother offering any explanations and simply said that those who did were racist because the explanations would interfere with contemporary activist campaigns. In his own words:
"But at the same time as one "pure-race" hypothesis was hitting the dust, another was rising. Ancient Australian skeletons were being discovered in Victoria and southern New South Wales, and they seemed to show great diversity. None of them were Negritos, Murrayians or Carpentarians, but those from Keilor and Lake Mungo were like modern Aboriginal people, whereas some (not all) of those from Kow Swamp had very flat, sloping foreheads, and some people even likened them to so-called "Java Man", Homo erectus, that had preceded modern humans (Homo sapiens) in the region to the Northwest of Australasia at least as late as 300,000 years ago. Unfortunately, although Alan Thorne, the describer of the Kow Swamp skeletons, never actually said that they were Homo erectus, the idea that an extremely primitive people preceded the present Aboriginal people in Australia, and was eliminated by them, seems to have seeped into some folks' consciousness just like the Negritos did. Negritos or Homo erectus - either way, the Aborigines were not the first possessors of Australia so the land doesn't really belong to them and the whites needn't feel too bad about dispossessing them. Really good fodder, this, for the One Nation Party, and the Prime Minister needn't feel he has to say "sorry".
If sarcasm and the need to conform to contemporary activist campaigns were highly valued qualities in academic inquiry, then it appeared as though Groves had made a powerful and compelling argument.
Some theories based on the skeletal record have proposed that the first humans in Australia were the "negrito" Tasmanian people, who were displaced by "Murrayans", who were in turn displaced by "Carpentarians". Academics like Dr Colin Groves have proposed that the theories are racist and that there was only one migration and all Aborigines are the descendents from that one migration.
of Africa Theory
theory proposes that 1.4 million years ago Homo erectus left Africa
and spread throughout Europe and Asia. In Europe, Homo erectus evolved into the Neanderthals. In Asia, most Homo erectus
stopped evolving - with the exception of a small group in the Indonesian archipelago
that branched off to become Homo floresiensis (aka the Hobbit). Unlike most of the Homo erectus in new Asian environments, which stagnated,
the Homo erectus that stayed in Africa continued to evolve and eventually became Homo sapiens.
About 200,000 years
ago, Homo sapiens left Africa. They spread throughout the globe and conquered
or out-competed Neanderthals and Homo erectus. The
last Neanderthal died out around 30,000 years ago. The last Homo erectus died
out somewhere between 200,000 and 30,000 years ago. The last Hobbit is believed
to have died out in a volcanic eruption around 10,000 years ago. After
conquering Homo erectus in Indonesia, Homo sapiens moved to Australia. If Homo
erectus had made it to Australia first, then they too would have been conquered.
In a nutshell, 200,000 years ago an African
tribe, either through superior food gathering ability or open war, started the
extinction of all hominin species living throughout Eurasia.
the Out-of-Africa theory was work by Allan Wilson who provided evidence in 1987 that
all modern humans share a single female ancestor who lived in Africa approximately
200,000 years ago.
Interactive journey of humanity - http://www.bradshawfoundation.com/journey/
408, 7 Dec 2000, p. 653
Continuity or Multiregional Evolution
Man is a huge spanner in the works for the Out-of-Africa theory because it can't explain
how Mungo Man looked liked modern humans, yet was not related to any human that
had left Africa in the last 200,000 years. A
'Multiple-Regions' theory was held up as the answer. If Out-of-Africa is a theory
of war, then Multiple Regions is a theory of sex. The
theory proposed that Homo erectus was not conquered; rather, once Homo erectus
left Africa 1.4 million years ago, it kept evolving on migration lines between
Asia and Africa (and possibly Australia). Interbreeding among nomadic tribes kept
most of the different groups on a relatively constant evolutionary track and ensured they remained the same species.
proponents of the Multiple-Regions theory argue that the Neanderthals in Eurasia and
the Hobbit in Indonesia were not unique species and therefore must
have contributed DNA to modern Homo sapiens.
Testing of Neanderthal DNA has produced mixed evidence. Repeated testing of mitochondrial DNA of modern humans found no evidence of Neanderthal DNA. Because mitochondrial DNA is passed on by women, the lack of it indicated that Homo sapiens do not have a female Neaderthal ancestor. Even though sapiens don't have female Neaderthal ancestors, they do have male Neandethal ancestors. In 2010, 60 per cent of the Neaderthal had been mapped and was subsequently compared to modern humans from Papua New Guinea, Europe, Asia and Africa. It found that 1-4% of modern human DNA, in populations outside of Africa, was Neanderthal in origin. While the results found evidence of male Neanderthal in non-African Homo sapiens, there was no evidence of Homo sapien DNA, either male or female, contributing to Neaderthal DNA.
The results suggested that Neanderthals had the ability to breed with Homo sapiens (so were not a unique species) but breeding was minimal. Furthermore, the one-way flow of genes, and the absense of Neaderthal mitochondrial DNA in modern humans, would suggest it was only a few Neanderthal men breeding with Homo sapien women. On the whole, the two Hominins bred very little.
Perhaps the small flow of genes could also be attributed to migration routes. The Neanderthals may have evolved independently
because they were an ice age people living in caves. Ice age Eurasia was just
too inhospitable for nomadic Homo erectus. Likewise,
in the Indonesian archipelago, the ancestor of the Hobbit may have been cut off
from migration routes due to changes in sea levels or volcanic activity. Consequently,
they also become a unique species.
from the Neanderthals and the Hobbits, all other Homo erectus keep migrating,
keep breeding and kept evolving on a constant track. Eventually they evolved into
At some stage in the last
850,000 years (or longer), either Homo erectus or Homo sapiens made the crossing from Java to Australia.
These hominins were the ancestors of Mungo Man. It would not have been a difficult crossing to make. Rats are believed to have made the crossing 2 million years ago.
200,000 years ago, females from an African tribe started spreading their genes
through the entire arc between Australia and Africa. This
spreading of female genes could have occurred as a result of a nomadic African
tribe emerging from Africa and breeding throughout Asia. It could also have occurred
as a result of an Asian tribe going to Africa, and forcibly taking women back
to Asia. (*Although evidence indicates that all humans might have had a common female African ancestor 200,000
years ago, as yet there is no evidence to show a common male ancestor.)
60,000 years ago, Homo sapiens with African ancestors started migrating into Australia, and joined Mungo Man. The first group of Africans were known as Robust due to their
heavy-boned physique. This group was significantly different from the slender body shaped Gracile of Mungo Man that was already in Australia. The Robust soon came to dominate Australia. Many thousands of years later, perhaps more people with a Gracile body migrated to Australia. The similarity in shape probably stemmed from parallel evolution rather than recent common ancestors. Alternatively, the Robust Homo sapiens perhaps evolved a more Gracile shape due to climatic changes. (Robust shapes were more suited to cold climates and tackling megafauna. Gracile shapes were more agile and had better endurance.) Aborigines today have a Gracile body shape that is like the 62,000-year-old Mungo Man but unlike the 10,000-year-old Kow Swamp people.
Sites showing where Homo erectus was found. Debate exists about European sites. Some skulls have been found in Australia that show Homo erectus features but they have not been categorised as Homo erectus. Homo Flores (the hobbit) was found on the eastern side of the Wallace line, indicating that its Homo erectus ancestor had the capacity to make ocean crossings.
One view on human evolution. Note, overlap is only deemed to have occured in Europe where Homo sapiens and Neanderthals co-existed. Homo floresiensis was not included.
If Out-of-Africa is to
be believed, then human occupation of Australia has to be less than 200,000 years.
Exactly when humans arrived would have been determined by how long it took Homo
sapiens emerging from Africa to cause the extinction of the Homo erectus tribes
spread throughout Asia. If Multiple Regions is
to be believed, the length of human occupation of Australia can be greatly extended.
Homo erectus was known to be in the Indonesian archipelago 850,000 years ago.
If they had made the crossing to Australia, then hominin occupation of Australia
could be anywhere up to 850,000 years.
is generally believed that Homo erectus was not intelligent enough to make the
boats that would have been required to cross to Australia. Arguably though, making
a raft or a canoe is much much easier than making stone tools that can kill animals.
Furthermore, Homo erectus obviously had a degree of intelligence as it
had crossed rivers and adapted to diverse climates on its way from Africa to Java and Peking.
It should also be noted that the Hobbit was found on the Australian/Papua New Guinea side of the Wallace Line. In previous ice ages, Papua New Guinea was part of the Australian zooalogical regions and Flores showed signs of both Asian and Australian fauna. Stone tools on the island of Flores have been dated at 840,000 years, which proves that Homo erectus was capable of making a sea crossing. It also proves that after crossing the Wallace Line, Homo erectus gained the opportunity to migrate into Australia.
The Wallace Line - A stretch of deep water that separates the zoological regions of Asia from those of Australia and Papua New Guinea. 840,000-year-old Homo erectus tools have been found on the Australian New Guinea side.
Sahul – The land mass that comprised PNG and Australia during the last ice age. Australia was not as isolated as some people believe.
The possibility that Homo erectus made it to Australia was supported by archaeological excavations from 1968
to 1972 by Professor Alan Thorne at Kow Swamp, which found skeletons
showing Homo erectus features. The main problem with seeing them as Homo erectus was that they were between 10,000 and 13,000 years old. If they were Homo erectus, then it would suggest that either Homo erectus lived in Australia until very recently, or came in a migration wave after Homo sapiens and then died out or was bred out.
for human evolution
the Fittest proposes that the strongest and most intelligent will eventually
emerge triumphant. Out-of-Africa supports the theory because it proposes a smart and
strong African tribe was able to cause the extinction of all other hominin species
spread across the globe. It caused the extinction due to its superior food gathering
ability and/or superior battlefield might.
Multiple-Regions theory indicates that Survival-of-the-Fittest is only half true.
Physical weakness can aid promiscuity and therefore the proliferation of genes. In the case of the Neanderthals, the fact that male Neanderthals survives in the DNA of Homo sapiens but female Neanderthals DNA does not suggests that Neanderthal men probably raped Homo sapien women and the offspring was raised by Homo sapien tribes. It would have been easy for Neanderthals to rape the women because they were far stronger. (It is possible that Neanderthal boys/men were adopted by Homo sapien tribes but this would not explain why Neanderthal women were not adopted.) While Neanderthal men could rape Homo sapien women, Homo sapien men were too weak to rape the stronger Neanderthal women and to carry them back to the tribe as typically occurred in hunter gatherer communities. Ironically, by being strong, the Neanderthal women were not forcibly inducted into tribes that could survive.
Similar problems may have been experience by the women of Mungo Man’s tribe. If they were particularly agile or strong, other groups of Homo sapiens would not have been able to force them to join their tribes as was custom in hunter gathering. If the other tribes came to dominate, then the women’s evolutionary lines would have gone extinct like those of the Neanderthal.
1) Groves, Colin, (2002) Australia for the Australians http://www.australianhumanitiesreview.org/archive/Issue-June-2002/groves.html)
3)Susan C. Antón, Karen J. Weinstein (1999) Artificial cranial deformation and fossil Australians revisited Journal of Human Evolution Volume 36, Issue 2, February 1999, Pages 195–209