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Human Evolution

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kristin lehner

on 4 March 2013

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Transcript of Human Evolution

Human Evolution Pan Troglodytes
What makes Chimpanzees so different than us? -shorter lifespan
-smaller body size
-smaller brain to body size ratio
-less intelligent
-Foramen Magnum is angled backwards
rather than beneath the skull http://www.thebigzoo.com/Animals/Chimpanzee.asp Sahelanthropus tchadensis 6 Million years Ago Chimpanzee lineage and our own split Sahelanthropus tchadensis is one of the oldest known species in the human family tree
Because of lack of fossil evidence some people believe they are not human ancestors Human Qualities Ape-like Qualities Small Canine teeth
Short middle part of the face
A spinal cord opening underneath the skull instead of towards the back as seen in non-bipedal apes. •Small brain
•Sloping face
•Very prominent brow ridge
•Elongated skull http://www.macroevolution.net/sahelanthropus-tchadensis.html#.USvXbB1flcw This caused us
to form into
two seperate
Pongidea Sahelanthropus tchadensis was found in Chad, Africa
It's known by some people as the first species to be bi-pedal
Due to the placement of the Foramen Magnum, the head was held on an upright body, associated with walking on two legs. Australopithecus anamensis 7-6 Million Years Ago They share many qualities of both humans and Apes 3.8 - 4.2 Million Years Ago Due to the structure of their tibia, it proved that they supported their weight on one leg at a time, just like humans
Marks on their wrist bones indicated they had strong hand tendons useful for tree climbing Thick enamal on their teeth showed they ate hard-to-chew twigs, plants, and nuts The divergence of man and chimpanzee
lineage Hypothesis: part of the population of the common ancestor became geographically isolated from the
rest of the population over a long period of time,
by a river or mountain. These geographic isolation's would prevent the process of gene flow from the population on one side of the barrier to the
population on the other side. Over time, different mutations would accumulate in the two populations, resulting in different evolutionary paths and an inability to interbreed. Once these two populations can no longer interbreed, there can be no gene
flow between them and each will follow
its own divergent evolutionary path Jaw remains suggest that this species was the direct ancestor of Australopithecus afarensis
Their fossils are significant because they represent the earliest evidence of bipedality in the human fossil record. Australopithecus Afarensis 2.8 - 3.9 Million Years Ago One of the longest-lived and best-known early human species—palaeontologists have uncovered remains from more than 300 individuals Aferensis's Children grew rapidly, resulting in early adulthood They had footprints similar to our own, as in their heel was the first part to strike the ground, their toes aligned, and central arches They were not very fast on two legs due to their short thigh bones They started walking because they were forced to spend more time on the ground due to the Earth changing Because they were able to stand taller, it was easier for them to see further. Which benefited them by seeing food or what was ahead of them Because of their long strong arms, and curved fingers they were able to climb trees Lucy Lucy is estimated to have lived 3.2 million years ago, and is apart of the Australopithecus Afarensis family Donald Johanson was the paleoanthropologist responsible for finding Lucy's remains They had collected several hundred pieces of bone, which represented 40 % of a single skeleton. They knew these bones belonged to one single individual because there was no duplication of any one bone Lucy had gotten her name from the Beatles song, "Lucy in the Sky With Diamonds" because it was playing at the time they discovered her Homo Habilis 2.3 - 1.5 Million Years Ago Earliest of our ancestors to show significant increase in brain size
They ate meat and due to the protein in the meat, their brains grew
They also ate bone marrow, which is very nutritious
Stone tools were found near its fossil remains so we know this species had developed the ability to modify stone into tools
Stone tools represented a change in mental capabilities and a shift toward new survival strategies
These tools allowed them to eat a variety of things
Finger-like bone proportions suggest the human-like ability to form a precision grip
They didn't have big teeth or muscular jaws so they struggled during dry season
Their savaging lifestyle made them inventive
If they saw vultures in the sky they knew that meant there was food near by
The Brocas area in their brain grew a little bigger so it was possible for rudimentary speech
Paranthropus Boisei 2.1 - 1.1 Million Years Ago Has a specialized skull for heavy chewing
Strong sagittal crest anchored the large chewing muscles
Large molars
Strong, flaring cheekbones
nick-named 'Nutcracker Man' because of its characteristics
They were primarily vegetarian
They had small brains
They are highly specialized, which is good in the short term but prevents adaptation and then leads to extinction
There brains can't think how to handle change
The disappearance of their foods (due to changes in climate or other factors) on which the Boisei specialized has been used to explain their extinction. When these foods disappeared the Boisei went extinct because they had evolved a specialization for a food that was no longer available
They are a gorillas direct ancestor so they are more of a human cousin Homo Ergaster 1.5 -1.9 million years ago First of our ancestors to look like modern humans
Tall, slender, relatively hairless
Flatter face
Projecting nose
Their pelvis shows women were broad hipped and short
Changes to their shoulders, chest, and waist improved their body's balance and allowed them to run Ergaster means "work"
We inherit our big brains from them
They understood the world around them
They could tell animal prints apart and which way they were going
They could tell a certain cloud meant rain
They could understand each other
They're the first to have a human voice and communicate with each other
Mandibular symphysis shows strong markings for the digastric muscle, which some interpreted as proof of language
Ergaster were able to make good stone tools
- Stone tools helped improve technology, they created more durable tools that maintained their sharpness longer. They mostly used it on meat, bone, and animal hines They also understood fires were used to be gathered around and prepare food, they also used it as a social gathering
They cared for sick/injured family members They were the first to see the whites of their eyes
-This is an important quality to have for communication They have the most sophisticated cooling system. Their hairless bodies let the heat escape them. Sweat controls their temperature, so this allowed them to be out in the sun for long periods of time while other animals would have to stay in the shade. They were also able to control their breathing, which helped them run after other animals. Homo Erectus 1.89 million - 143,000 years ago When Homo Ergaster left Africa to
explore Asia they turned into Homo
Erectus Homo Erectus shares a lot of common characteristics with the Homo Ergaster Modern human-like body proportions with relatively elongated legs and shorter arms compared to the size of the torso. These features are considered adaptations to a life lived on the ground, indicating the loss of earlier tree-climbing adaptations. Homo erectus was directly ancestral to the earliest members of living species Homo sapiens.
The first appearance of hominids outside of Africa.
First indication of extended childhood.
The cranial bone is thicker than in earlier hominids.
The development of a more barrel-shaped chest.
Reached modern human size in terms of height. Homo Neanderthalensis 230,000 - 30,000 Years Ago Brain was larger than modern humans
Angled cheek bones
Huge nose for humidifying and warming cold, dry air
Their bodies were shorter and stockier than our, which was an adaptation to living in cold environments
Their skeletons show signs of broken bones and other traumas
Bone injuries similar to rodeo riders
Bones are thick and heavy, and show signs of powerful muscle attachment They made and used a diverse set of tools
They controlled fires
Lived in cold climates
Lived in shelters to protect themselves from the cold weather
They were skilled hunters of larger animals
Made and wore clothing from animal hinds
Teeth show signs of heavy wear, suggesting they were used as tools to make clothing
They made symbolic objects
Neanderthals are our closet extinct human relative They lived in tight nit communities They buried their dead and even marked their graves with flowers. No other primates have ever practiced this behavior They survived two ice ages in Europe They individually didn't live very long, so it was hard to teach practices to the children Homo Sapiens (Humans) 200,000 - Present Humans descended from Homo heidelbergensis.
During a time of dramatic climate change, we evolved in Africa
We have very fragile skulls, that are a lot bigger in size than earlier primates
Less heavy brow ridges
Our jaws are less heavily developed, with smaller teeth.
How Did We Survive? We specialized tools and made a variety of smaller, more complex ones including composite stone tools, fishhooks and harpoons, bows and arrows, spear throwers and sewing needles.
Due to our large, complex brains, Humans found they could control the growth and breeding of certain plants and animals.
This lead to farming and breeding animals
Our bigger brains helped us survive by allowing us to communicate on a whole new level.
We could share our ideas, and make the world we are living in better by our creativity
A dilemma that our primates faced in the past was that their brains were growing too fast and their pelvis was too narrow, which caused problems while giving birth
What happend for us was we got born early, our brain isn't fully grown at birth and it triples the size after we are born. For most other primates the brian develops fully before they are born.
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