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Human Evolution

91606Demonstrate understanding of trends in human evolution4 creditsExternal

Introduction to Human Evolution


Where did I come from? Well I don't want to think about that. However, I do want to know about where the human species came from. This topic covers how we have come to be over the last 170,000 years (modern H. sapiens) as well as looking at our divergence from the ape lineage around 7 million years ago. It answers those important questions of why our fingers go wrinkly when they get wet and why we no longer swing between trees and like to sit in front of computers and learn stuff.

This topic is all about patterns and trends, what were the patterns leading toward bipedalism, tool uses, culture and looking at the bigger ideas of our biological and cultural evolution as a species. Here are a couple of definitions to learn.
  • Biological evolution is the transmission / passing on / evolution of genetic information (from parent to offspring).
  • Cultural evolution is the transmission / passing on / evolution of learned behaviour / ideas / knowledge / non genetic information.
Biological evolution is fast while cultural evolution is slow.  cultural evolution can happen within a lifetime / generation.  Biological evolution can happen only once from generation to generation / occurs over many generations.


Thinking about the topic


Full notes from nobraintoosmall - this really is a great set of simple notes to use to start a mindmap or study notes. 
Polamar education - Good to read
Human evolution Prezi from Nayland College.
Interactive timeline (excellent link!)

The ultimate guide to this topic that beats any text book is the Waikato University website. Here is a link

If you want a basic introduction before learning the concepts of the standard read the following link Here Click on the begin the program link at the bottom of the page and it will start into the audio book.

This standard is about trends. What is a trend? Well its a A general direction in which something is developing or changing. That means our species has been developing or changing over time. It is your job to now find out and think about how this change has happened, what is the change and what world changes, both abiotic and biotic may have been driving it! Easy!



Thinking about the evidence for human evolution?



Content - Big picture


The groupings are important in human biology. The primates are the order containing the humans, apes, monkeys and lemurs. The Hominids (Hominidae) are the group containing humans, African apes and orangutans. The Hominins (homininae) are the tribe consisting of the genus Homo and several generations of early bipedal apes.


Before you start look at the following 2 power points (Alan Wilson centre)

Powerpoint 1

Powerpoint 2

Download the interactive software from http://www.becominghuman.org/ Its awesome.

Interactive timeline can be found here

An introduction to mammals and the primates


Mammals

Mammals have the following features

1. They suckle their young

2. They (generally) have hair and sweat glands

3. They (generally)give birth to live young

4. They are warm blooded

5. They have an external ear and 3 middle ear bones (this allowed for more efficient hearing – other vertebrates have only one)

6. They have four different kinds of teeth – incisors, canines, premolars and molars.

7. Larger brain, especially the fore-brain: cerebrum

Primates

Trends

  1. Relatively large cranium
  2. forward-facing orbits/binocular vision
  3. brow ridge
  4. walled off eye sockets
  5. generalised dentition.
  6. Strong social relationships. They often live in groups.
  7. 5 digits (fingers and toes) per hand or foot. Digits are long and mobile
  8.  Prehensile (grasping) hands and often feet.
  9. Nails rather than claws
  10.  Limbs are plantigrade (the entire foot is in contact with the ground)
  11. Clavicle (collarbone)is large as it helps strengthen the shoulder joint for hanging from branches.
  12. Hip and shoulder mobile
  13. Large brain and eyes
  14.  Usually only have single young – difficult to carry twins in the trees.
  15. Long term care of the young.
  16. Reduced olfactory centre of the brain (as vision became more important than smell)
  17. Orbit (eye socket) is closed off by bone
  18.  Colour vision – allows primates to tell when fruit is ripe
  19. Stereoscopic, binocular vision – eyes face forward so two fields of vision overlap.


Primate Locomotion

Some primates are arboreal, some are adapted to living on the ground and some spend time both in the trees and on the ground.


Arboreal locomotion

1.      Quadrupedalism – the arms and legs are of more or less equal length and importance eg lemurs.

2.      Modified quadrupedalism ie leaping and clinging, climbing. The animals trunk is vertical before and after each leap, as well as in the resting position eg tarsiers.

3.      Brachiation – this involves the use of the arms which become longer and are used to suspend the body during feeding and to move the body by arm swinging eg gibbons

Ground locomotion

1.      Quadrupedalism eg baboons

2.      Knuckle walking – walking on the backs of the middle parts of the third and forth fingers of each hand eg chimpanzee

3.      Bipedalism – walking on two legs eg humans

We are part of the group Primate. Here is an excellent video covering how scientists are looking for the first primate ancestors.





Trends in human biological evolution

Bipedalism

A good link covering the hominids - Dead Link

Skeletal changes linked to bipedalism




What was driving it? Selection Pressures/ environment

As the climate became warmer and dryer in Africa around 6 mya, the forests were receding and became scattered woodland. Hominins at the time would have to have travelled longer distances to gather resources. Being able to brachiate would become less important than being able to walk efficiently, as walking would be the most common mode of travel.

But why?

Early hominins that were able to take advantage of available food most efficiently would be selected for. One way of taking advantage is by carrying more food away at one time. The individuals that could do this by moving on 2 legs and using both hands to carry food would be selected for.




Normally here the question compares a type of ape with a Homin/ H. sapiens. It will be looking at the overall skeleton or a section such as the limbs (legs and arms), feet/hand, or skull. You will have to discuss both species in relation to if they are bipedal or quadrupedal. For this you will have to learn/ memorize all the differences.

Important Bones to know


An awesome site can be found here where you can compare and contrast skeletons of the primates/ humans - Link

Compare Hominid skulls here - Dead Link

Foramen magnum - the large whole the spinal cord goes through in the bottom of the skull.
Occipital condyles - sides of the FM, smooth, rounded surfaces where the atlas vertebra rest. (these are rearward in quadrupeds and central in bipeds)

vertebral column - The backbone of chimps and gorillas is a simple curve. Bipedals have a S shaped backbone.
Hip girdle - Long hip bone in quadrupedal animals (to support abdominal organs). Humans have a bowl shaped girdle to reduce the stress on the part of the hip that transmits body weight.

Femur and knee - Knees directly underneath the centre of the hip girdle.

Below the feet, chest, hands and teeth/ jaw will be covered in more depth.

Great Apes vs. Hominin


Early Hominin vs. Current

Apes (quadrupedal)

H. sapiens (bipedal)

Reason for change

Curved spine


S- shaped spine


Absorbs shock of bipedal motion

Flat foot

Arched foot

Absorbs shock – smoother motion & “spring” 

in step

Opposable big toe

Big toe separated from other

toes in chimpanzee

Big toe in line

/ big toe in

line with other toes in hominin

Promotes linear motion (not side to side

“waddle”) – more efficient

Toes in line  improved locomotion as big

 toe acts as a pivot for thrust.

Pelvis is long and narrow

Pelvis short and wide

Supports organs above, also must allow 

for bigger head during birth

Changed shape of the hominin pelvis

beneficial in locomotion:

Changes position of muscle attachmen

more efficient locomotion;

Carrying angle – more efficient

locomotion because movement

notside to side (or implied) /

balance /stability when walking.

Bottom of femur smaller

Bottom of femur buttressed

Increased support of vertical mass (directly weighing down on knee joint)

Femur attaches to knee vertically

Femur angled to lower leg (valgus angle)

Allows better weight distribution; balance (Centre Of Gravity above knee), therefore more efficient motion

Long arm: leg ratio

Shorter arms

Not needed for brachiating (moving in trees)




Now this question often links to other living hominids. Here are all the hominids in power-point form (animated). - Dead Link

Gorilla

Foramen magnum at back,– gorilla is quadrupedal and relies on nuchal crest / neck muscles to keep head upright



Australopithecus

Foramen magnum more forward –Australopithecus is mostly bipedal but relies on nuchal crest / neck muscles to keep head upright.

Homo Sapiens (us!)

Foramen magnum is centred under the skull – H sapiens is fully bipedal with head balanced on spine.
  • The valgus angle in her femur to bring feet / knees beneath hips/ directly below the centre of gravity thus indicating bipedalism.
  • The valgus angle – greater stability when walking bipedally
  •  Foramen magnum under skull showing spine was vertical indicates bipedalism
  • Reduced nuchal crest means less neck muscles to hold head up indicates bipedalism
  • Broad & shallow (cupshaped) pelvis supports (not 
    protection)internal organs / 
    better attachment for large leg 
    muscles.
  • Non-divergent toe allows 
    “thrust” in walking (NOT 
    balance). 

Skull

Human 

rounded brain case (enlarged brain) with reduced sites for muscle attachment, especially those used for chewing and aggressive facial displays which are no longer called for.

Ape

Flatter brain case (smaller brain) which allows for greaternmuscle attachment sites needed for aggressive facial displays.


• bipedal as foramen magnum underskull / more centralise• bipedal as reduced nuchal
crest.
• not bipedal as foramen magnum islocated at the rear.

More detail

foramen magnum underskull /more centralised suggests that skull is balanced on top of vertical spinal column, implying bipedalism.
Note: Pivot and lever not accepted – must be thrust / push

The change to bipedalism


A fantastic podcast can be found here.

As the climate changed and less forest was available, Ardi would have had to walk further to gather food. Longer legs and straighter spine for bipedalism gave a height advantage, allowing Ardi to be able to see further, allowing her to find  resources more easily. However, being taller might have made her more visible to predators. In addition having hands free means that she could carry items such as tools for gathering more food, or food from another place to consume at a later date. However, changes to bipedalism make Ardi less well adapted for arboreal life, potentially reducing protection and food gathering.

Read the following link - Dead Link

An excellent animation looking at the main areas.


Excellent animation covering bipedalism

What would be driving bipedalism to happen?

Environmental change brought new selection pressures. A Change of Environment
About 20 million years ago, the Indian plate  collided with Asia and thrust up the  Himalayan range. The climate became drier and the forests of what is now Africa and Asia contracted. – The result was an increased area of savanna habitat, with fewer trees. 
Bipedalism freed the hands which enabled hominins to develop tools, which have in turn enabled them to access meat, which is rich in protein and energy needed to increase brain development and therefore endocranial capacity, leading to development of speech, understanding and conceptual thought (Broca’s, Wernickes and increased cerebrum)

Bipedalism also freed the hands to allow for tool development and learning of more complex skills, and therefore selection for larger brains, requiring increased endocranial capacity. 

In both the savannah and
forest bipedal hominins 
would have been upright 
allowing them to see
predators. In the savannah 
they would have been less 
susceptible to heat exhaustion 
as less of their body surface is 
directly in the sun and they 
would be more exposed to c
ooler air breezes. In the
forest it would have been 
easier to reach food.In both 
habitats movement is more e
fficient.

Why bipedality? 


•can cover more distance to gather more resources as bipedal locomotion is more efficient. 
•height makes her more visible to predators(vulnerability implied)
• Upright: Less likelihood of overheating when walking in the open / doing other activities
•The changing climate means that the niche is diminished, forcing her to leave the trees. 
• As bipedalism leaves her hands free, can carry resources from place to place, giving her a survival advantage.

Thermoregulation- The upright posture exposed less surface to the tropical sun.
Efficient Locomotion- It is more economical than  knuckle walking used by the other great apes. In a more fragmented woodland the hominids would have to travel further per day for resources.

Child Birth


Most of the questions have related to the size of the pelvis opening.

Increased diameter of inlet in sapiens so modern infants are born  with a proportionally larger
head (cranial capacity) than erectus infants.

Trade-off between +ve and –ve;

• Ability to give birth to largerbrained babies
• Impact on locomotion – more efficient with smaller pelvic inlet

Summary of Adaptations for Bipedalism

 

Position of the foramen magnum

Moved from the back to the centre of the skull – this allows the skull to balance on top of the spine and less energy expenditure is required by the muscles in the neck to keep the skull upright.

Position of the occipital condyles (the part of the skull that articulates with the vertebral column)

They have moved from the back of the skull to the middle of the skull to keep to keep the head above the centre of gravity

Rib cage

Flattened from front to back which moves the centre of gravity closer to the spine. This improves balance.

Spine shape

Changed from ‘C’ shape to ‘S’ shaped. This allows the weight of the chest to sit above the pelvis, rather than further forward. This improves both balance and it absorbs the shock of walking.

Pelvis shape

The pelvis has become more bowl shaped (broad and short). This results in:-

(a)    Improved balance

(b)   The support of the upper body

(c)    Enlarges the valgus angle.

The bowl shaped pelvis also increases the surface area for the attachment of large buttock muscles (gluteus maximus).

Femur length and shape

Femur is stronger, longer and angled inwards from the hip so that the knees nearly touch (increased valgus angle). This assists the upper body to be positioned above the centre of gravity for walking.

Overall the legs are longer than the arms in humans.

Knee joint

The bottom of the femur (the knee joint) has a buttress of bone called the lateral condyle, that stops the sideways deflection of thigh muscles during walking.

Shape of the foot

The foot has changed in two main ways:-

(a)    The foot has changed to become a platform. The toes are short, with the big toe beside the others and forward thrusting (ie it is non-opposable). The foot has lost all grasping ability.

(b)   The weight is placed on the outer edge with the inner side elevated into an arch. This provides a shock absorber effect and a spring that facilitates long distance travelling.


Changes in skull and endocranial features


A good animation

Fun activity on digging for fossils

Changes in the manipulative ability of the hand




Apes

H. sapiens

Reason for change

Long fingers

Shorter fingers

No longer need to grip branches (brachiate). Precision grip important for tool making and use.

Curved fingers

Straight fingers



Changes in skull/ endocranial (inside skull)


Apes

H. sapiens

Reason for change

Smaller cranial capacity (~450cc)

Bigger cranium (~1450cc)

Increased brain development

Sagittal crest

Large zygomatic arch

Large jaw

Teeth bigger

Brow ridge

No Sagittal crest

Small zygomatic arch

Small jaw

Teeth smaller

No brow ridge

More refined diet, no need for really strong chewing muscles, muscle attachment points, or teeth

Nuchal crest

No Nuchal crest

Head vertical on spine – less muscle attachment needed.

Foramen magnum on angle/back of skull

Foramen magnum central/bottom of skull

Vertical spine with skull on top

No Broca’s and Wernicke’s areas

Broca’s and Wernicke’s areas present

Used for language

Less folding of cerebral cortex

Cortex much more folded

Related to memory, attention, language, awareness, thought, etc… developed as social structure allows more time, and hands free to carry out abstract tasks

Cerebellum less developed

Cerebellum more developed

Needed for balance, as well as coordination and tool use


Trends in human cultural evolution


Remember the definition! 
Cultural evolution is the transmission / passing on / evolution of learned behaviour / ideas / knowledge / non genetic information.

Here is a quick overview.Here is a quick overview.

Evidence of our cultural evolution


Evidence that is biological
  • The cranial capacity and shape of the skull can indicate ability for speech / language / tool making ability / high intelligence (must have consequence of high intelligence).
  • The (reduction in) sagittal crest / zygomatic arch / jaw size / tooth shape or size can indicate dietary change / cooked food.
  • DNA analysis could indicate how closely related the bone / fossil is to other fossils
Evidence that is cultural
  • The way in which the skeleton has been buried can indicate the development of spititual beliefs / greater level of care / sign of respect.  The material used and the method used in making the tools can show that it had been produced at a different site.
  • ‘worked’fragments can indicate learned / cooperative behaviour / foresight / planning.
  • The presence of fire places can indicate a trend towards cooking food / dietary changes
  • The presence of large animal bones can indicate cooperative behaviour / communication / planning
e.g.
The way the skeleton has been buried can be compared to other burial sites of the same age to identify significant similarities in the evolution of spiritual beliefs and care for the dead. The production of and the material used in the ‘worked’ fragments can be compared to sites of the same age, to establish a broader understanding about a particular tool culture. Charcoal from the fire places and skeletal bone can be dated using radiocarbon techniques, as the site is 
likely to be Neandertal or archaic Homo sapiens and therefore not older than 50,000 years, for which radiocarbon dating can be used.The skull detail, such as cranial capacity, DNA and age can be analysed and compared to others of similar age and / or genus, to confirm existing evidence or identify new trends / variations in biological evolution of Neandertal.

Its over an hour but a good watch. Better than Shortland Street anyway and is based on the Neandertal

Use of tools (stone, wood, bone)


Hands 



Once the hands were freed from brachiating or knuckle walking, there would have been an adaptive advantage to being able to manipulate objects more carefully, such as food or simple tools. Fingers became less curved and the thumb fully opposable, there was an increase in dexterity

Finer / precision grasp / grip (NOT better grasp / grip)  Greater dexterity (not for 
fingers)  Fine motor control Opposable / dexterous thumb  Manipulate smaller objects

also

hand that allows greater 
precision and dexterity, 
eg.
• opposable thumb
• sensitive skin
• A longer thumb.

Examples of trends in tool manufacture


• length of cutting edge increases
• number of blows increases.
• more precise tools
• more refined tools
• more time taken making tools.


Tool periods



Oldowan - Oldowan tools are pebbles with a few flakes removed from one side. less sophisticated and fashioned on one side only.

Acheulean – bifacial, tear-drop shaped, flaked, hand axes for chopping / scraping (butchering food).
Acheulian tools appear to have a 
tear-drop shape, made with greater 
precision and many more finer blows 
to remove more flakes to produce 
specific shapes such as the hand axe. 
Acheulian tools required more 
planning to make and more stages in 
their manufacture.

H.erectus fossil sites show evidence of Acheulian tools.

Mousterian – made from flakes, resharpened edges, Levallois method; scrapers & spears, attached stone tools to handles, flint.

Palaeolithic – specialised, made from several materials(flint & bone), precision / refined / intricate, fine blades & points; spear thrower, bone needles, fish hooks, wide range of uses

Tools have progressed from the basic removal of stone flakes to create tear-drop shaped hand axes in the Acheulean culture. Next was the Mousterian culture where the Levallois method was used to remove a sharp-edged flake of stone. Lastly came the finer detailed Palaeolithic tools such as needles and hooks made from bone and flint.

How does this relate to the hominins?

Simplest tools made by earlier species

Habilis and Oldowan tools; erectus and Acheulean culture; Mousterian of neandertals and early sapiens
extremely complex tool kits of later sapiens.

H.erectus fossil sites show evidence of the use of fire. Fire would have encouraged groups to gather together and provided light at night for longer days where erectus could have spent more time in communication and thinking through the days problems. Fire allowed H. erectus to live in more northern communities affected by greater seasonal changes and colder nights and winters, improved longevity by killing microbes through cooking meat/fish, helped in cooperative hunting by herding animals away from fire.
Benefits of using fire
  • at night/in colder areas
  • anti-predator defences eg. fire scares away predators
  • easier to digest/destroy parasites/access greater range of food / more palatable / preserve food
  • for toolmaking/preparing food /planning
  • to get more food
  • harden points of wooden tools/weapons.
  • able to keep warm in cooler regions 
  • Use of fire lead to better / stronger tools more successful hunting and increased food 
  • Use of fire to cook food / meat to access additional protein / energy
  • Use of fire as protection from predatory animals. 

clothing


abstract thought (communication, language, art) 


Broca’s OR Wernicke’s area linked to development of language is important.


Communication

Facial expressions important 


Speech

Culture requires intelligence and communication
Areas of the brain essential for structure and sense of speech
Broca’s area – concerned with speech
Wernicke’s area – concerned with comprehension of language 
The lower the voice box, the more sounds can be articulated.
Singing and chanting 
Essential for remembering kinship lines and tribal history
Better hearing and listening skills as a result of speech

Art 

drawings of pictures and symbols on cave walls, bone carvings, clay statues

food-gathering

(hunter-gatherer, domestication of plants and animals) 

Domestication

• Domestication happened, using crops and animals from the local environment, and adapting them to provide regular food supply for a group of individuals.

•Climate warming meant that agriculture appeared suddenly in many places as crops could be grown there [change]. This meant that people did not need to move to gather food, so could conserve energy and support larger populations [advantage]. 

•With more food available, larger populations could be supported [advantage]. However, this meant that there was more waste to deal with, potentially bringing pests and diseases [disadvantage].

•With crops being harvested at one point in time, food supply would be erratic through the year [disadvantage]. New technologies such as pottery containers for food storage would have been one solution to this [solution].

•With domestication of crops came a reduction in the variety of food available compared to hunter gathering. {disadvantage}. Trading between different groups gave greater food variety {solution}


shelter


(caves, temporary settlement, permanent settlement).
What shelter brings
planning 
• communication 
• cooperative behaviour 
• division of labour 
• suggests a larger group (NOT just communities)
Home Base Theory
At some sites, concentrations of tools, stones from other areas and bones are found.
This suggests that early hominins were not just carrying things around, but were focusing on one site as a home base.
Adults hunted and left young behind, and then brought all produce back to be shared
Sharing of food lead to complex societies
Clearly defined by the time of Homo erectus


Spiritual / religious / afterlife beliefs


a concept of the afterlife is shown by the ivory beads left by the dead – a gift for them (in another life). the idea that death was not the end and the mammoth shoulder blade could be used for protection in the next life.

Being settled in one place


By being settled in one place only some people would be toolmakers which enabled better specialised tools for better hunting / opportunity for learning from specialists (specialisation of roles).


Hominin overview


Interactive timeline (excellent link!) - This covers many of the hominids

Dead link to Youtube


An excellent link to an animation on the "missing link". - Dead Link


Sahelanthropus tchadensis


Lived in wooded areas 

Most of cultural evolution is pure speculation


No bones below the skull have been discovered yet, so it is not known whether Toumai was bipedal or not. Brunet et al. say that it would be a not unreasonable inference that it was a habitual biped because it shares characteristics with other hominids known to be bipedal. Other scientists have pointed out the foramen magnum (the hole through which the spinal cord exits the skull) of Toumai is positioned towards the back of the skull as in apes, indicating that the skull was held forward and not balanced on top of an erect body.

Australopithecus group


Only debatable evidence that they made tools, and no evidence that they had home bases or shared food. Probably opportunist feeders.

Anatomy adapted to bipedal locomotion
High brachial index (forearm/upper arm ratio) relative to other hominids
Sexually dimorphic to a degree greater than Homo and Pan, but less than Gorilla or Pongo
Height: 1.2 m – 1.5 m; Mass: 30 kg – 55 kg (estimated)
Cranial capacity: 350 cc – 600 cc
Postcanine dentition relatively large, enamel thickened compared to contemporary apes and humans
Incisors and canine relatively small, little sexual dimorphism in canines compared to modern apes




Paranthropus genus




Some evidence they used bones or perhaps sticks to dig up roots (this would leave no fossil evidence though) 

Evidence suggests robustus ate course, tough food supplemented by small insects.

More information

Homo genus

YouTube Video


Development of speech 

 Enabled by Broca’s area of the brain. First seen in H.habilis. 

Development of tool-making 

 H. habilis was known as the Handy man and made Oldowan tools. 

 H. erectus used Acheulian tools and was known as the Fire maker. 


 H.Neanderthalis used Mousterian tools and began to attach stone tools to handles. 


 H. sapiens used advanced tools of flint and bone. Used blades and points. Called Upper Palaeolithic tools.

Homo genus



Development of speech 

Enabled by Broca’s area of the brain. First seen in H.habilis. 

Development of tool-making

 H. habilis was known as the Handy man and made Oldowan tools. 

 H. erectus used Acheulian tools and was known as the Fire maker. 

 H.Neanderthalis used Mousterian tools and began to attach stone tools to handles. 



 H. sapiens used advanced tools of flint and bone. Used blades and points. Called Upper Palaeolithic tools.

Homo genus



Development of group living and culture

H. habilis – successful hunters, made shelters and lived in bands of about 12 people

H. erectus - built shelters (huts) supported by wooden poles, serious co-operative hunters

H. heidelbergensis – able to hunt large prey (rich diet led to increased size), were cannibals, built shelters and used fire

H. neanderthalis – intelligent, lived in caves, built stone walls, dressed in hides, buried their dead, had strong social bonds.

H. sapiens – skilled hunters, lived in large groups, engraved and painted on walls, carved statues etc


Patterns of dispersal of hominins


An excellent into to this topic can be found here (animation).
A good PowerPoint can be found here

Hominins refers to living and fossil species belonging to the human lineage. This is a subgroup of hominids, a group which includes both humans and the great apes.

Lisa Matisoo-Smith presented a LENS seminar on 16 September 2011 focusing on using DNA to understand the settlement of the Pacific. For more details, seehttp://lens.auckland.ac.nz/index.php/Pacific_Migration

From the Alan Wilson Centre (direct link)

These presentations trace the story of how modern humans spread across the globe, beginning around 65,000 years ago with migrations out of Africa, and ending with the settlement of New Zealand 750 years ago. In part 1, students will learn how researchers are using genomics to address questions such as: How many migrations out of Africa were there? Did Homo Sapiens interbreed with Neanderthals and other ancient human lineages as they spread across Europe and Asia? What does “race” really mean? The PowerPoints are aimed at senior biology students (Years 12 and 13), and fit with the Nature of Science and Living World strands of the curriculum. The pdf file contains notes for teachers to accompany the presentation.

Africa to Aotearoa part 1 (5,829 KB)

 Africa to Aotearoa part 1 - Note (1,627 KB)




Out of Africa hypothesis

A good image showing the process. (Click to see full size)


  • H. Ergaster left Africa 1-2mya – different populations became geographically and reproductively isolated, evolving into variants through the old world.
  • Modern humans evolved in Africa from erectus then 160,000 years ago migrated out of Africa replacing the existing erectus populations with minimum interbreeding
  • Mitochondrial DNA evidence shows more variation in Africa than in the rest of the world – indicating that the rest of the world all came from a common ancestor who left Africa.
  • Multiregional is argues by fossil evidence showing transitional forms (subject to interpretation)
  • Molecular evidence is undeniable and shows a high degree of homogeneity.




A great video - listen and make notes, its great.

Excellent basic animation - Dead Link

 Intial migration of early Homo, such as H.erectus, H.heidelbergensis and H.neanderthalis, did not contribute to modern humans, but there was a second wave of new humans out of Africa approx 200 000 years ago.   It was a fully modern H.sapiens that then replaced whatever populations then occupied Asia and Europe.   Intial migration of early Homo, such as H.erectus, H.heidelbergensis and H.neanderthalis, did not contribute to modern humans, but there was a second wave of new humans out of Africa approx 200 000 years ago.   It was a fully modern H.sapiens that then replaced whatever populations then occupied Asia and Europe.   Transitional forms found mainly in Africa.  Modern traits found first in Africa and then later elsewhere as they spread.   Since the species is young there should be little diversity



Why would early Homo need to migrate away from Africa?

Habitat change with specific example of how this lead to greater survival, eg. new hunting / foraging areas to exploit

• Pressure to expand into new ranges; follow prey /food plants to reduce competition

• Potential for drop in sea level to expose new migration routes(land bridges)


Evidence

Multiregional (and others) a comparison.



Use of mitochondrial DNA

•mtDNA has been used because it is passed on from mother to child and is not changed due to meiosis. 

• Mutations occur at a steady rate in mtDNA and can be used to estimate how long ago two species shared a common ancestor.

How could they migrate so rapidly?

It would be possible to reach many areas via land bridges asit means a shorter /safer route. Straits between islands could be narrower – more likely to use boats/rafting to cross straits. Coastal travel would be easier on newly-exposed continental shelf with ready food supplies in shallow coastal 
waters.

Why was Europe slow to colonise?

Eropean climate much more severe than the more southerly coastal route, forcing more southerly travel /so harder to get food. 
• Neandertals were already present
in Europe creating competition.
• Too cold in Europe as adapted to
warmer climates so migrated further south.

MultiRegional

·        Asian fossils show a clear transition from older hominid to modern H.sapiens.  The oldest H.sapiens fossils outside Africa were in Australia, and are 60 000yrs old.  Northern china fossils show no evidence that African features ever replaced the ancient Chinese in this region.   Instead there is a smooth transformation of ancient peoples into the present populations of East Asia and the Americas.  Post-Neanderthal people in Europe show mixtures of modern and archaic African features.   Mitochondrial DNA analysis is flawed because;  Present-day patterns cannot show links that become extinct.   Whenever no daughters are produced the mitochondrial line dies out.

Evidence

Out of Africa

·        Mitochondrial DNA shows high degree of similarity between all modern human populations that most likely occurred with the past 150 000 – 200 000 years ago

·        The oldest H.sapiens fossils have only been found in Africa, 80 000 – 120 000 years old

·        Humans arrived in Europe late – about 80 000 years ago.  Fossil evidence shows that moderns humans appeared in Africa before the Neanderthals had disappeared in Europe so could not be descendants of the Neanderthals

Evidence that H Erectus could survive outside of Africa and the conflicting evidence that they did not.

Could survive.

H. erectus skulls show increased 
cranial capacity and fossil sites a more 
advanced Acheulian tool culture, 
which would have been better for 
hunting and scavenging. 
H. erectus skulls show increased 
cranial capacity indicating better 
communication / planning / 
cooperation leading to improved 
chances of survival.
H. erectus have more advanced 
Acheulian tools therefore would have 
had the ability to access meat as a 
supply of additional calories / energy.
H erectus used fire – able to keep 
warm in cooler regions / spend time 
making tools for hunting or 
processing meat at a home base / Use 
of fire lead to better / stronger tools 
more successful hunting and increased 
food.

Conflicting evidence about being the 
first hominin to leave Africa comes 
from Georgia (Europe / Asia) where a 
species, named H. georgicus, dated 
earlier than H. erectus 1.6-1.7 mya), 
with a cranial capacity of only 600-
780 cm
 and associated with Oldowan 
tools has been found. H. georgicus is 
not associated with fire or the ability 
to produce the more advanced tool 
culture for accessing high protein 
food, thought necessary to survive 
outside of Africa

Comparison


The greatest variability is found 
within African populations which are 
the oldest. There is less genetic 
diversity in Asian and European 
populations, which suggests they are 
not as old as African populations.
European / Asian populations 




Conclusion

Another excellent documentary to watch - Dead link to Youtube


The real hobbit - Homo floresiensis

Other information - Dead Link to Youtube


Dating Rocks, Fossils and Artefacts

Dating Technique

Counting

Method

Dating Range

(Years BP)

Datable Material

Carbon dating C14

(Carbon decays to Nitrogen)

Radioactive decay

100 – 60,000

Bone, charcoal

Potassium – argon

(Potassium decays to Argon)

Radioactive decay

10,000 – 100 million

Volcanic rocks

Uranium decay

Radioactive decay

1,000 – 1 million

Coral and shells

Fission track

Radioactive decay

3,000 -100 million

Volcanic rock, pottery

Thermoluminescence

(Sample is burnt)

Trapped electrons

1,000 – 200,000

Fired pottery, charred flint tools

Dendrochronology

Counting tree rings

0 – 12,000

Tree trunks

Earth magnetic polarity

Iron particles trapped in lava

700,000+

Undisturbed volcanic rock.

Index Fossils

(Relative date)

Find well known fossil species

Any time when fossils are found

Sedimentary layers

Amino acid racemisation

Light polarisation – handedness of molecules

Up to 200,000

Bone and teeth (containing protein)



The future of human evolution


An excellent podcast covering this idea.

Readings - Attached below
Ċ
Mike Wilson,
Sep 10, 2013, 8:20 PM
Ċ
Mike Wilson,
Sep 10, 2013, 8:20 PM
ĉ
Mike Wilson,
Sep 9, 2013, 8:17 PM
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