5,000 years ago: Egyptian pyramids.
10,000 years ago: Domestication of plants and invention of agriculture.
20,000 years ago: Ice aged hunters paint on cave walls.
6 million years ago: Our ancestors went on the path from ape to human.
 |
| The Skull of Toumai |
Fossils of the species Sahelanthropus Tchadensis, discovered in Northern Chad in 2001 is 6-7 million years old. It may be a common ancestor of apes and humans. Toumai, the name of the fossil skull, may have walked on two legs but scientists don't know for sure.
What began the switch to bipedalism? Before Selam and Lucy's time, two fossils of the species Australopithecus Afarensis, who walked on two legs around 3.3 - 3.2 million years ago, East Africa was a large tropical rain forest. When they were alive, however, their environment began to dry out. As the forest began to disappear, our ape ancestors needed to walk longer distances than before. Walking upright saves energy which is how our ancestors evolved to walk on two legs. As energy demands changed, so too did our ancestors. (Chimps consume 4 times as much energy as modern day humans).
Brains of chimps are fully matured at the age of three while human brains take 2 decades to fully mature. Selam's brain, at age three, was only 75% formed which proves that her childhood was more prolonged, becoming more human and less ape.
Ape brain size remained relatively stagnant for over 4 million years.
 |
| Homo Habilis |
The first tool-makers were Homo Habilis (Handy Man), 1.6-2.5 million years ago, judging by the cuts in animal fossils and the tools themselves, which preserve better than bones. Homo Habilis has an increase in brain size from Lucy and Selam's kind as the former has an elevated forehead while the latter do not. Homo Habilis no longer had the projected snout of an ape.
What jump started human evolution 2 million years ago? Wild climate fluctuation and lots of environmental change. Areas in Africa went from lake, to drought, to lake, to volcanic ash to grassland etc. The tendency of the environment to change made our ancestors more adaptable. While brain size was stagnant, so too was the climate. As climate instability began 2 million years ago, those who could not adapt died out and more intelligent species, like Homo Habilis survived. Variability was the driving force of human evolution. We are creatures of climate change.
 |
| Homo Erectus |
Homo Erectus (Set Upright) 1.8 - 1.3 million years ago - were tamers of fire, hunters, world travelers, toolmakers, and creators of the first human societies. They showed displays of creativity, intelligence, and caring for their species. Turkana boy was discovered in 1984 and is the most complete early human skeleton ever found. He was 5 feet 3 inches tall, and by looking at his fossil teeth, only 8 years old. A human skull is 1400 cubic centimeters; Turkana boy: 900 cubic centimeters; and chimps: 400 cubic centimeters. His skull is primitive with a smaller brain capacity but it is much more similar to modern human skulls than an apes skull. Homo Erectus created hand axes. Turkana boy had an abscess in his lower jaw that would have caused unbearable pain without knowing what was wrong with him. Evidence suggests he died from an infection and that he died in water, which explains his preservation. H. Erectus recognized flaws in stone tools and made decisions on which tools to keep and which tools to discard. With a bigger brain and body, Homo Erectus needed more meat. Endurance running and high activity in the middle of the day gave H. Erectus an advantage in hunting. They had lost their thick coat of body hair and had the ability to sweat unlike the other animals in the Savannah. The strategy of hunting was to run after an animal until it tired out then butcher it with a stone ax. This is called persistence hunting. Other animals pant when in hot climate and cannot pant when sprinting. Humans cool down as sweat evaporates off their hairless bodies, giving them an advantage in the animal kingdom allowing them to run long distances. Homo Erectus became more social around the fireplace when they were cooking. They went extinct around 50,000 years ago.
 |
| Homo Sapien and Neanderthal Migration |
When did humans leave Africa and why? They left around 1.8 million years ago and migrated around modern day Georgia (country). The first humans to leave Africa were very primitive early Homo Erectus. They had smaller brains than Turkana boy, but used stone tools. Homo Erectus left Africa as soon as they showed signs in Africa. They didn't know they were leaving Africa, but followed the game. The migration was very slow, possibly 1 mile per year.
Homo Floresiensis (Hobbit) fossils were discovered in 2004 on the island of Flores in Indonesia. They may have existed only 12,000 years ago and they used stone tools with a brain size of only 400 cubic centimeters. Some scientists have suggested they were dwarfed Homo Erectus due to disease, but others suggest the more probable theory of island dwarfism and that they were evolved from Homo Erectus or a more primitive ancestor.
 |
| A mother orangutan with her baby |
A mother orangutan will not let another animal to touch their baby for 6 months and are in constant contact with their child while human mothers share their baby with many others and abandon their infants much more often than any other higher ape.
As recent as 50,000 years ago, there would have been 4 different human species coexisting at the same time.
Homo Heidelbergensis (Heidelberg Man) fossils were discovered a half million years ago in modern day Germany and Northern Spain and were 6 - 7 feet tall. They later evolved into Neanderthals in Europe and Homo Sapiens in Africa.
 |
| Homo Neanderthalensis |
Homo Neanderthalensis (Neanderthal Man) lived in Europe for 300,000 - 400,000 years. Neanderthals were the most advanced humans on Earth until Homo Sapiens arrived. Their parietal lobe and temporal lobe were a bit smaller than homo sapiens. Homo Neanderthalensis were carnivores with a diet closely related to a wolf despite having berries and plants nearby. Hunting was risky business as they did not use projectile weapons but stone axes and stabbing spears. Very few Neanderthals lived beyond the age of 30. They went extinct around 25,000 years ago. Neanderthals were most likely able to speak.
 |
| Sexy Modern Homo Sapien |
Homo Sapiens (Wise Man) arrive while vast ice sheets cover the African continent around 200,000 years ago. Homo Sapiens came from 600 breeding individuals. Modern humans are 99.9 percent DNA identical to each other because of the bottleneck effect. Many humans died out when homo sapiens came into existence. 4-6 areas in Africa were safe enough for survival during these severe climate changes and humans almost went extinct. Homo Sapiens are descendant from these small populations. Homo sapiens encountered Homo Neanderthalensis in Europe. With our smaller bodies, we had less energy demands than the neanderthals, who consumed as much energy as a bicyclist riding the Tour de France every single day. Homo Sapiens invented projectile spears with bone tips which meant less risk and wider range of game. When Homo Sapiens arrived in Asia and Europe, the cave lion and the hairy mammoth went extinct along with many other mammals. In Australia, large animals became extinct within three thousand years of our arrival. Neanderthals were pushed to extinction and Homo Sapiens became the only homo genus on the planet. We are the most adaptable species and the only ones to conquer Europe, Africa, Asia and the Americas at one time.
Note: most of the information I've gathered is from the "Becoming Human" 3-part Series on PBS and from other credible internet sources. All of this is written in my own words.
