Migrant Flora and Fauna
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Turning evolution upside down
"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?"
In 1974, the discovery of Mungo Man turned the conventional theory of human evolution upside-down. Mungo Man was a hominin who is 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.
Aside from undermining the Out of Africa theory of evolution, Mungo Man also undermined other migration theories relating to human colonisation of Australia. Early theories proposed that the first humans in Australia were the "negrito" Tasmanian people, who were displaced by "Murrayans", who were in turn displaced by "Carpentarians". For ideological reasons, these theories gave way to a single migration theory that proposed that there was only ever one migration to Australia and all Aborigines are the descendents from that one migration. It was difficult to reconcile this theory with Mungo's skeleton. Although Mungo Man was dissimilar to the 10,000-year-old robust skeletons being found in Australia, his bone structure was similar to modern day Aborigines. Multiple migrations helped explain the variance in skeletons.
Tasmanian Aborigines looked a lot like Africans.
Out of Africa Theory
The 'Out-of-Africa' 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 Asia, 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.
Supporting the Out-of-Africa theory is 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/
Regional Continuity or Multiregional Evolution
Mungo 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 is held up as the answer. If Out-of-Africa is a theory of war, then Multiple Regions is a theory of sex. The theory proposes 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.
Most 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 a female Neaderthal ancestor, they do have a male. 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. There was no evidence of Homo sapien DNA contributing to Neaderthal DNA.
The results suggest that Neanderthals had the ability to breed with Homo sapiens, 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.
Aside 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 Homo sapiens.
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 female African ancestor 200,000 years ago, there is no evidence to show a 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. The Robust soon came to dominate Australia. Either they killed most of the Gracile or they bred most of them out of existence. Many thousands of years later, more Gracile either migrated to Australia, or a group of Gracile that survived the Robust invasion starting dominating the Robust. 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 is not included.
Implications for Australia
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.
It 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 is 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.
Oldest living culture?
In Australia, it is a very common belief that Aborigines have the longest continuous culture in the world. Both the Out-of-Africa and Multiple-Regions Theory undermine the claim. If Out-of-Africa were true, then Africans have occupied their respective piece of land for up to 7 million years. This is far longer than the 60,000 years of occupation in Australia.
One group of these Africans left the continent sometime in the last 200,000 years and arrived in Australia around 60,000 years ago. If they were no longer considered to be culturally continous because they occupied different land, then their cultures were much younger than the Africans they left behind.
If Multiple Regions is to be believed, then the whole concept of “Continuous Culture” becomes a silly one. The theory proposes that humans have always been on the move, have always being mixing up their genetics with other groups, and have always been exchanging ideas. Such mixing is a strength, and naturally, trying to say one culture is continuous and old, while another culture is discontinuous and young, is really quite irrational.
Furthermore, if culture is merely defined on genetics alone, then again, the Aborigines are not necessarily 60,000 years old. If Homo erectus made it to Australia from Flores and became human, then potentially Aboriginal culture is around 850,000 years old, which is about the same age as Chinese culture if it too evolved from Peking Man, who died in Beijing 850,000 years ago.
Implications for human evolution
Survival of 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.
A Multiple-Regions theory indicates that Survival-of-the-Fittest is only half true. Physical weakness can aid promiscuity and therefore the proliferation of genes. The men in Eve's African tribe may have been unable prevent a stronger tribe carrying away its women and turning them into sex slaves. Although the tribe's men would have died out, the women would have survived to become the ancestors of all humans today. Alternatively, the African tribe may have traded its women to other tribes. The women could have resisted if they had been stronger, but the cost of being stronger would have been their genes being confined only to Africa.
Implications for the demise of the Neanderthals
In 2010, researchers provided evidence that 1-4% of DNA in modern human populations in Europe, Asia, and Papua New Guinea was Neanderthal in origin. However, there was no evidence of Homo sapien DNA in the Neanderthals. In other words, although Neanderthals could breed with Homo sapiens, Homo sapien populations were far more successful in ensuring their genetics survived.
There is little evidence of Neanderthals being absorbed into the Homo sapien population. If absorbtion had occured, Homo sapiens in Europe should have more Neanderthal DNA than those in Asia and PNG, which they do not. It seems that Neanderthals infused some DNA into early Homo sapien populations that passed through the middle-east, but otherwise contributed very little.
Because there is no evidence of female Neanderthal DNA in the mitochondrial DNA of Homo sapiens, it appears that breeding was between Neanderthal men and Homo sapien women. There was no breeding between Homo sapien men and Neanderhal women. Because the flow of genes was one way, it is unlikely that Homo sapien tribes and Neanderthal tribes were exchanging women. Instead, it appears as though some Neanderthals raped Homo sapien women, but the reverse did not occur.
The demise of the Neanderthals has always been problematic for proponents of Survival-of-the-Fittest. The Neanderthals were far bigger and stronger than Homo sapiens. In bare-handed fight, no Homo sapien would have stood a chance against a Neanderthal. In terms of intelligence, the Neanderthal's brain cavities were on average 10-20 per cent larger than Homo sapiens. If, as Out-of-Africa proposes, one tribe emerged to conquer all other hominin species, why wasn't this tribe from the Neanderthals, which were the strongest, and potentially the smartest, hominins that have ever lived?
Perhaps the answer to the Neanderthals' demise was in the physical strength of their women and the lack of caring by their men. The absence of Neanderthal mitochondrial DNA in modern humans would suggest that the evolutionary line of Neanderthal women went extinct. Therefore, the Neanderthal DNA in modern humans probably came from Neanderthal men breeding with Homo sapien women. The one-way flow of genes is best understood by considering the violent nature of reproduction in paleolithic societies. In hunter gatherer societies, women were exchanged with other tribes and subsequently raped, or men attacked other tribes and raped the women. If a woman was very strong, and a man was very weak, he would struggle to rape her. Therefore, it was in the woman's interests to evolve a weaker body that could be raped. In addition to being impregnated, if she had a body significantly smaller than the male, then she could be carried off to another tribe where her children would survive if her tribe had been decimated in war. This may not have happened to Neanderthal women because they were too strong to be carried away. Admittedly, if Neanderthal men could have carried weaker Homo sapien women back to their own tribes, then some Homo sapien DNA should be found in Neanderthal DNA. The absence of such DNA would suggest that Neanderthal men raped women in Homo sapien populations, but left them in those populations. This would also suggest that Neanderthals probably never formed relationships with Homo sapien tribes to exchange women. They just raped and left the women. If the woman was not adopted by another tribe after her own was decimated by Neanderthals, she would die along with the Neanderthal baby that she was carrying.
Although their unborn children were at greater risk of dying, it would actually make sense for Neanderthal men to rape and leave the women. Because they largely lived in caves and ate meat (80% of their diet), if Neanderthals carried the woman back to their tribe, she would be an extra mouth to feed. Aside from caring for children, women didn't have much economic value in the Neanderthal society.
Contrasted to the Neanderthals, Homo sapien women held great economic value. Because meat was only 30% of the Homo sapien diet, the majority of food was supplied by women gathering food. The more women in the Homo sapien tribe the better.
Over time, the women most likely to be targeted, traded and taken back to tribes were those with smaller bodies. Larger bodied women, such as Neanderthals, may have died out because they were too strong for Homo sapiens to carry away. Furthermore, children were most likely to survive when fathers carried the mothers back to the tribe. Neanderthal men probably didn't do this so their children were less likely to survive. Homo sapien men did carry women back so their children were more likely to survive.
In summary, because Neanderthal women were strong, Neanderthal women were not impregnated by Homo sapiens. Furthermore, because Neanderthal men did not carry women back to their tribes, relatively few children of Neanderthal men survived. Even though Neanderthals and Homo sapiens could breed with each other, the Neanderthal women's evolutionary line became completely extinct. The Neanderthal men's line went mostly extinct.
Because they ate different food, potentially Homo sapiens and Neanderthals could have co-existed and for perhaps 15 mellenia they did. However, because Neanderthals were a small population, any warring with Homo sapiens, or any Homo sapien encroachment on their hunting sites, would have had an impact. Unable to pass on their genes as effectively as Homo sapiens, the Neanderthals were slowly replaced.
The alternative explanation is that Neanderthals suffered because they lacked genetic diversity and lacked the contact with other tribes necessary to foster change or develop culture. Because they lived in small family units, they may have become inbred in both genetics and ideas. On the other hand, the nomadic Homo sapiens kept breeding with other groups of humans, kept exhanging ideas and kept changing. While the Neandethals had more potential for intelligence, their insular ways resulted in them not using that potential.
Activity 1 - Politics and ancient history
Purpose - To understand how identity and politics influences the interpretation of facts
1) Ancient skeletons that seem to predate a wave of migration from Africa 200,000 years ago have been found in China, Indonesia, England, Israel and Australia. In the following tables, speculate how the theories could influence the identity of indigenous people and migrants the various regions around the world. For some ideas, consider the writing below:
Activity 2 – Sex and evolution
Purpose- A topic that is taboo in many respects, and one many of us would be uncomfortable thinking about due to its confronting nature, but one which could help illuminate humanity today and provide ideas on alleviating sexual deviance
For most of the last 200,000 years, human women have had little opportunity to chose their sexual partners. How might this have shaped evolution? For ideas, read below: