5 MILLION YEARS AGO

The African landscape is getting drier and with fewer trees to be seen across vast swathes of the continent. About the only remnants of this great African rainforest today may be found in difficult-to-reach places such as the Congo along Africa's central west coast.

Before sunlight was able to reach the ground and bake the soil, primates (including the evolutionary branch that would lead to humans) were naturally nocturnal creatures living in the trees. It would be rare to come down to the ground unless there were some tasty fruits that have fallen. Then the rest of the time would be spent sleeping during the hotest part of the day. However, as time passed, and with fewer trees on the African continent and more regular exposure to sunlight during the day, the primates slowly became specialists in gathering food during the day and sleeping at night. Later this would be supplemented with more foraging of food on the ground before running back to the safety of the trees should they see predators around. Certainly at some point, these inquisitive creatures with little to protect themselves from the predators have to make the journey from one tree to the next to find more food.

Thus the need to walk upright became increasingly more important for certain primates.

4.9 MILLION YEARS AGO

Our early ancestors were not yet crafty creatures in developing weapons and working together in a social group to fend off predators. Some might throw the occasional stones at some predators, but larger predators were another thing altogether. We were still highly vulnerable as a species, especially during relatively long walks between trees. In fact, it is believed we were still pretty much on the predators' menu thanks to sabretooths, giant carnivorous bears, lions, leopards, wild dogs and giant birds of prey.

Richard Coss, a psychologist at the University of California, argues that the transition from being hunted to the hunter stage has not been a particularly smooth one. He believes our ancestors had encountered numerous predators of which many were detrimental to humans in the early stages of our evolution. Nevertheless, as time went by, humans developed better muscle co-ordination, walked more often on two feet to constantly survey the land for potential threats and new sources of food, used a communicative language for organising whole groups of hominids to achieve a common goal, and eventually built a technology of tools to help deal with the predators.

Thus, as Coss has surmised, all our technology, socialisation, language, the aggressive behaviours displayed by males, our social values of trust and loyalty, our need to hoard as many tools as possible, and even many of our deepest fears and phobias are all part of our evolutionary hangovers from these ancient times when humans had to deal with the predators.

If this is true, such regular reinforcement of these difficult times including the presence of prehistoric drawings and some awesome stories handed down through the generations of various "monsters" seen in those days would be carried over in our genes and produce what we call instincts, which are essentially hardwired patterns stored in the brain. Richard Coss agrees. As Ken Grimes writes in his article Hunted!, published in the New Scientist magazine:

"[Richard] Coss is convinced that we still bear the marks of our time as a hunted creature. Inherited instincts and intuitions can remain hardwired into the brain for a very long time, he says, even once they have become obsolete. This might explain relic behaviours such as the Moro response - a reflex grasping action displayed by newborn babies when startled. It resembles the way in which an alarmed infant monkey clings to the furry belly of its mother. "This ancestral infant response, which disappears at about six months of age, is therefore at least six million years old," says Coss." (1)

As further evidence, many people are still likely to be startled to this very day whenever movies from Hollywood producers depict predators on the big screen despite the safety of our modern society. And what about the general tendency for males to be aggressive when solving problems? Could we have learnt this now instinctual behaviour in the males species over millions of years?

Whether or not our minds and everything that we have developed and acquired today is the product of millions of years of experiencing what it is like being attacked and "eaten alive" by predators on a regular basis, further research is still being carried out on this controversial idea. (2)

4.1 MILLION YEARS AGO

Nearly 4 million years ago, hominids called Australopithecus walked the Earth. They had a skull structure slightly more human than ape to be considered a likely early ancestor.

Two species have emerged with this genus: Australopithecus afarensis, and Australopithecus africanus. Either of them could be a contender for the lineage towards humans. What we do know is that these early hominids were small social creatures of 1.2 for earlier descendants and later 1.5 metres in height for the highly accustomed to life on the ground. While trees remain a useful place to seek protection, working together in a social group and in sufficient numbers helped to keep many of the smaller predators away. Only the largest predators, such as lions, would be willing to take on a human even in a group situation. At any rate, the number of fossils found for this species so far would suggest that they lived in eastern and southern Africa. They walked on two feet (with slightly bent legs) and had a brain no larger than a modern chimpanzee (or roughly one-third of a modern human). Although characteristically ape-like in appearance, primitive human-like features can be observed on the skull structure including a low forehead, a relatively large forward-jutting jaw, and small canines not projecting well above the other teeth. They also had widely-separated cheekbones but this could be due to the way the smaller skull size and larger jaw structure helped to exaggerate this feature.

In terms of the way this species lived in the environment, the Australopithecines probably retained their ancestral instinct to climb trees as observed in the curvature of the finger and toe (based on an analysis of the remains of a 40 per cent complete 3.18-million-year-old (3) skeleton nicknamed "Lucy" from Ethiopia, Africa).

Walking regularly on two feet became essential to this group of hominids for the following reasons:

• To gain a better view of the surrounding countryside as required to find a number of potential food sites and observe possible threats to one's survival such as a predator or uncontrolled fire;
• Africa at this time was losing its great forests and has now become a patchwork of forest and savanna. Hence for Australopithecines to migrate safely from one forest to the next, they definitely had to walk upright. As an incentive, the large wetlands in some parts of Africa may have forced the Australopithecines to walk upright to avoid drowning themselves in the water;
• To show leadership or aggression in a group, it is important to increase one's physical height by standing tall on two feet (and yet still be able to crouch down and keep a small size when hiding from predators). It is a bit like the way two male antelopes will come together in a fight. The antelopes would temporarily get up on two feet and come down on each other as a sign of greater aggression, strength and size;
• To reduce surface area of skin exposed to sunlight and so lower the rate of water loss that would otherwise reduce the primates ability to endure the heat of the day as they chased prey over long distances or wandered around from one tree to the next searching for food; and
• To allow primates to free two limbs - one to hold and the other to manipulate - so they may build and use tools needed to make the task of acquiring food and fending off predators and other primate groups easier to perform.

The success of these creatures can also be better understood thanks to the following statement by Professor Tim White from the University of California at Berkeley, USA:

"Australopithecus became a superior omnivore, able to eat tubers and roots with more fibre and grit, adapting it better to times of scarcity during periods of extended drought.

They may have been small-brained, but they stuck around a long time, fully half of our zoological family's six-million-year existence on the planet." (The Canberra Times: Latest fossil finds in Ethiopia will provide the missing link: scientists. 15 April 2006, p.13.)

Fruit and nuts remained a staple for these hominids and supplemented the diet with scavenging for meat. But later, tools would be developed and better co-ordination of a group of hominids to take down prey would turn them more into hunters and less into prey themselves for other predators.

UPDATE
15 April 2006

There is a belief among the scientists that the more human-like Australopithecenes evolved from some species of Ardipithecus (a more ape-like creature) sometime between 7 and 4.4 million years ago. But the further we go back, the harder it becomes to determine which ape-like species had been a member of the human family tree. At present, scientists believe Australopithecenes are a direct link to humans primarily because they walked upright. As Professor Travis Pickering at the University of Wisconsin said:

"We know [Australopithecenes] it is a human ancestor because we have indication that they walked upright like us."

But walking upright may not be a sufficient criteria to make this assumption. It is quite possible other upright walking hominids could have been a direct link to humans. Now that we know Ardipithecus also walked upright, it is logical to consider this early species to be a direct ancestor to the human lineage.

3.7 MILLION YEARS AGO

Scientists discover embedded in 3.7 million year old volcanic ash footprints in Tanzania during the mid-1970s. What makes these footprints special is how they were produced by human-like creatures walking on two feet (possibly our own ancestors). This has to be clear evidence of early hominid creatures (and certainly those leading to modern humans) already walking upright by this time.

3 MILLION YEARS AGO

The earliest signs of a changing climate in Australia is suggesting that the beginning of a drying up of the continent would commence at this time. Initially much of the continent was covered in a semi-tropical to tropical rainforest, except for the southern most tip and in what is called the Snowy Mountains, which is more temperate and/or alpine-like. How far the thick forests extended would depend on whether periods of intense cold known as Ice Ages would appear, the amount of tilt of the planet (the greater the tilt, the less rainfall across the continent), and later the height of the Blue Mountain ranges and, eventually, the appearance of humans arriving to the continent.

2.8 MILLION YEARS AGO

Professor Gunther Korschinek and his scientific colleagues at the Technical University of Munich, Germany, have found stardust deep beneath the Pacific Ocean dated to this time.

The discovery suggests that the Earth was showered by this stardust material and higher levels of cosmic rays for up to a period of 300,000 years (4). The consequence of this is that any increase in cosmic rays reaching the surface of the Earth can affect the genetic material of early humans more readily. With this in mind, scientists have suggested the possibility that such rays could have assisted in the evolution of humans during this time. Or it could have been detrimental to humans. What probably happened is that those humans born with deformities most likely died through natural selection, whereas those humans born with unusually good characteristics were more likely to breed, resulting in the modified genes being transferred to future generations of humans.

Either way, the importance of radiation from various sources in modifying our genes cannot be underestimated. Radiation has, and will always, shape human evolution.

Did humans gain any new characteristics soon after being exposed to the cosmic rays from an ancient supernova?

1 TO 3 MILLION YEARS AGO

A scientific study of the fossilised bones of 324 baboons and 140 australopithecines uncovered during this period have confirmed that many did bear the marks of encounters with predators. The marks look typical of tooth and claw damage, especially of the big cats and predatory hyenas variety (5). It would appear our ancestors were more prey than predator during this time.

The group structure of Australopithecus is most interesting. Apparently, Australopithecus males would often stick in one group for all their lives. Females, on the other hand, were more likely to move to different groups. Could be a case of "the grass looks greener on the other side" when it comes to more food, although occasionally a prettier looking male may entice the female to make the move to another group. Whatever the decision, this ensured inbreeding within the species was minimised in order to produce a stronger species.

Australopithecus were scavengers of dead animals to help supplement their standard plant diet of leaves, roots and fruit. An increase in meat consumption would go hand-in-hand with an increase in brain size because of the extra nutrients (e.g. protein and fats) in the meat needed for the brain to develop and grow.

It would be another 2 million years before humans would learn to speak in a highly sophisticated and rational way and hence develop the necessary level of social organisation and technology capable of defending itself against virtually all great predators. Of course, this does not mean australopithecines could not make grunting noises and other forms of primitive verbal communication. It is just that the benefits of shaping and creating sounds to represent various object, events and action had not been seen as a benefit as yet.

2.5 MILLION YEARS AGO

Africa was experiencing a 10,000-year drought during the Pliocene epoch at around this time. According to some scientists, it was enough to devastate the gorilla population in southern Zaire and so allow a new breed of tough and brutal chimps to carve out an existence.

Some scientists believe it could also have affected early humans causing our bodies to adapt and find ways to get through periods of famine until the next period of abundance.

The drought is thought to be a natural cataclysmic event.

2.3 MILLION YEARS AGO

The great drought in Africa may have seen the emergence of the stone tool-wielding hominid known as Homo Habilis. By 2.3 million years ago, the numbers of these mostly meat-eating hominids were enough for scientists to pick up enough bones to make an analysis and finally put a name to this new species. It is unclear whether Homo Habilis invented fire for themselves and used the heat to cook the meat. We must assume the species ate mostly raw meat with limited amounts of plant materials unless bushfires provided some of the natural means of cooking the meat for these hominids. But the fact that this species began experimenting and coming up with useful tools, such as sharp-edged stones for use to carve meat and probably saw the benefit of attaching the stone to the end of a stick to throw at animals and a few more manageable predators that tried to make a meal of these hominids meant that it is possible a few may have worked out a way to create their own fire. Until spots where charcoal layers can be seen and dated to this time, we must assume Homo Habilis was not yet adept to creating fire.

The number of bones found of this species could also suggest its genes may have formed a part of modern humans given its advanced intelligence and ability to create and manipulate tools.

2 MILLION YEARS AGO

Africa continues to get drier. At this time much of the northern and eastern continent looked like grassland peppered with trees. No longer do we have the thick forests of the past as early hominids enjoyed for a very long time. And now some scientists believe they may know why. Apparently the tilt of the Earth was different at this time compared to today and was such that the polar ice caps could not melt properly in the summer time. The result was a locking up of more water as polar ice caps reduced the humidity in the air and with it the general rainfall in continents like Africa.

Despite the drier conditions, at least half a dozen different species of hominids appeared at this time. The large variety of hominids would coincide with a great diversity of animal life especially on the African continent, both of the familiar and unfamiliar types.

Of all the hominids present at this time, the oldest known artificially-made tools were definitely fashioned by Homo Habilis (although one could argue modern chimpanzees with less brain power than Homo Habilis can fashion a tool of their own and use it to affect the environment, such as picking out honey from a tree trunk with a stick or cracking the outer shells of nuts with a stone, suggesting hominids earlier than Homo Habilis should have had this tool-making and -wielding ability as well). From an abundant supply of stones and wood in certain parts of the European and African continent at this time, these hominids used their hands to create simple knifes and spear implements to improve hunting techniques and/or cut up meat scavenged from dead animals and later discovered a means of fending off invaders and predators from a prescribed territory.

Studies of skull and bone fragments suggested Homo Habilis were slightly taller and had a fractionally larger brain capacity than their predecessors, Australopithecus.

Did Homo Habilis develop the tools for gathering food first (e.g. scavenging meat) before using them as a defence against predators and eventually, with further refinement, for hunting? Some scientists believe it may have started from the latter. As Louise Barrett, a primatologist from Liverpool University, said:

"It is surely more reasonable to imagine that early humans discovered weapons as a means of driving away predators, then adopted them for scavenging [or gathering] and then hunting, than that we spontaneously "invented" hunting tools." (7)

Then again, this could end up being a "chicken or the-egg" situation. For example, a chimpanzee can quickly learn to cusp its hands into the shape of a bowl for temporarily holding food or water. Or why not a piece of bark for the same purpose? Some chimpanzees are even smart enough to select and even mould with its hands a piece of bark to gather food or water more efficiently. Since eating and drinking has to be performed more regularly and early in life compared to defending against predators (or even hunting), one could argue the tools were probably developed for gathering food first.

Whatever the truth, certainly by the time humans did start making tools, they would have eventually seen the value of using the tools both as a means of defending themselves against the predators and as a means of hunting and gathering food.

As these changes were taking place among the hominids in Africa, the original and thick gondwanic rainforests covering much if not all of Australia for literally many millions of years according to pollen records obtained from a number of sites around Australia, became only a minor part of Australia's vegetation by around 2 million years ago. More open and drier temperate forests would dominate this continent. The planetary tilt theory was likely to be the principal cause for this drying up of the continent. But there could be a deeper reason. We know that Australia is such a geologically inactive continent that regular rainfall and wind could have eroded the height of the Blue Mountains range along the eastern seaboard. Now looking more like large and rugged hills rather than mountains (as a person from Switzerland might describe them), a reduced mountain range would reduce the likelihood of cloud formation along these "hills" and with it a reduction in the amount of rain and how frequently it rains. Less water means there is likely to be a reduction in plant populations as they must adapt to drier conditions. Only a large inland sea at the centre of Australia could help to maintain any resemblance of reasonably reliable rainfalls on the mountain ranges. But with less and less rain falling on the mountains, we know the inland sea was shrinking.

It seems natural that a catch 22 would develop between the water cycle and plant populations. Plants can retain more water on the ground and help to keep the plants surviving for longer, but reduce the rainfall and it can get harder and harder to grab and retain the water for longer by the plants. Then the inland sea got affected by the reduced rainfall and through increased evaporation, not so many trees would grow. Even fewer trees over many summer seasons, resulting in less rain over the decades to replenish water on the ground. Then the inland sea would naturally shrink. Never enough to disappear completely. Even by 60,000 years ago, the inland sea was present despite the warmest summer conditions. However, something would change this situation. Another important event would help to accelerate the drying up of central Australia and further shrink the inland sea and eventually the unthinkable would happen: the inland sea would dry up. This was the time when the first humans walked the Australian continent and bringing with the the ability to create fire.

Should this inland sea disappear altogether for prolonged periods of time, new desert regions would appear. Any remaining trees would experience extreme bushfires. A high enough temperature can destroy seeds in the ground. Regeneration of plant growth gets much harder.

The continued and accelerated changes taking place on an increasingly wider scale would see Australia eventually turn into the driest continent in the world. No wonder Australians today find it hard to grow a decent crop when water becomes scarce (and then the occasional excessive amounts of rain on rare occasion during what is known as the El Nina event where warm Pacific waters reach the eastern coast of Australia can make growing plants in Australia a difficult proposition for many farmers unless they stick close to the eastern coast).

Turning back to the hominids in Africa, especially those that would eventually lead to the existence of humans, there existed another interesting hominid species from East Africa nearly 2 million years ago known as Homo Augasta. A creature with a more familiar human appearance compared to Homo Habilis, this one had a larger brain, were better adapted to a changing environment, produced the Rolls Royce of stone tools (e.g. axes), had greater social skills, developed the beginnings of a rudimentary verbal language for communicating with each other, and had the sophisticated tools and knowledge to reduce competition from other hominids and a number of predators.

We owe our large brains directly to Homo Augasta. In fact, the moment these prehistoric humans walked the earth and learned to develop important relationships with other people through language and getting together on a social level to achieve common goals and hence a chance to organise the group to perform specific tasks, the brains of Homo Augusta had to expand because of the range of extra patterns needed to be learnt through language and other skills as required to survive not only in the harsh environment, but also within the group itself.

Australopithecus may not have died out at the time Homo Augusta came on the scene, but there are indications that the former were on the decline. It is unclear whether natural events or competition with the new hominids was the cause for this.

1.77 MILLION YEARS AGO

Scientists discover a paleomagnetic reversal, an occurrence where the Earth's magnetic poles reverse positions, according to geophysical surveys of the magnetic patterns recorded in rocks on the sea floor. Between 1.77 and 1.5 million years ago, the north pole was actually over Antarctica and the south pole near the arctic region.

During a magnetic poles reversal, there is an increase in radiation and cosmic rays from space on the Earth's surface, including the equatorial regions. As the poles move to different positions, it can result in quicker death or extinction of some animal species and the sudden genetic mutation of other species. Could early humans have benefited from a change in their genetic material due to an increase in radiation levels during a brief period of magnetic pole reversal? (8)

1.8 MILLION YEARS AGO

A group of people known as the Neanderthals was known to have moved to Europe from the African plains at this time. Based on a combination of genetic, fossil, archaeological and other sources of information, scientists are now considering the high probability that the Neanderthals may already had the genes to support speech (and hence a communicative language). So when these people split from our ancestors in Africa during the emergence of Homo heidelbergensis and another group called the Denisovans, it is likely the Neanderthals and our original early ancestors living at this time already had the capability of speech and were communicating using a rudimentary language.

"Modern humans and Neanderthals and Denisovans are very similar genetically, and there are indications of interbreeding as well, strengthening this similarity," lead author of the study Dan Dediu said. He believes a gene involved in language and speech known as FOXP2 is present in all three groups..

As for the origins of human culture, Dediu further adds that the development of a language, no matter how primitive, would have seen the emergence of a culture among the group of people who prized speech and a language system. Furthermore, as language evolved so did the culture and vice versa. In other words, there was no need to wait for evolution in order to make the necessary changes in biology to allow for greater speech and a more sophisticated development of a culture. Humans probably forced the changes by seeing the advantages of speech and providing a basic language for communicating. Then culture just grew from there thereby paving the way for more sophisticated language and hence co-evolving over time to the state we see today.

As Dediu said

"Recent discoveries and reinterpretation of the Neanderthal archaeological record support its capacity for symbolic culture (including their) complex toolkit, complex social life and its capacity to persist in the harsh and fluctuating western Eurasian climate of the time.

The basic idea is that cultural change is not simply an effect of a better genetic background; culture does not have to wait for biology change, but culture generates new selective pressures to which our biology must adapt, changes in biology that might allow new cultural changes in a co-evolutionary cycle."

Dediu is a senior investigator in the Language and Genetics Department and is the principal leader for a project called "Genetic Biases in Speech and Language" aimed at determining how far back the gene for speech may have existed in humans. The study is based at the Max Planck Institute for Psycholinguistics.

What would the first speech have been like by early humans? Mark Sicoli, an assistant professor in Georgetown University's Department of Linguistics, suggested they probably whistled (an effective means of carrying basic information over reasonable distances) in a variety of different sounds to indicate different actions and behaviours to perform and/or to indicate what was needed, the remnants of which still exists among people in parts of Oaxaca, Mexico.

So far, all this work is not direct proof that humans did actually communicate and, if they did, whether the communication was through whistling nearly 1.8 million years ago. It is just that a number of key sources of information are certainly pointing in this direction. As Dediu concluded:

"If our proposal is correct, then we might not only carry some Neanderthal genes in our own genomes as traces of our past encounters, but also our languages might as well preserve some faint signature of their languages as well, but until rigorous testing is attempted, this must remain pure — even if exciting — speculation.