Homework Guided Reading Hominids Through Time (#12-21)
Learning Target I can explain how hominids evolved and what caused them to evolve.
What characteristics do they have in common? What characteristics are different?
Characteristics of All Primates Binocular vision: Eyes both on the front of the head. Each eye sees a slightly different view of the same scene and the brain merges them to allow depth perception. Flat finger nails Five flexible fingers (four fingers and an opposable thumb) Most primates (besides humans) also have opposable big toes Gorilla Foot
How are humans different from other primates? Bipedal (2 legs) skeleton is adapted for walking upright Human pelvis is vertical (holds skeleton upright) Gorilla pelvis tips ribcage, head, and neck forward Human spine is S shaped Gorilla spine is C shaped What else?
Make a prediction What are several advantages of being bipedal?
Which are bipedal advantages? A. Easier birth B. Less heat absorbed C. Walk further D. Can climb trees better E. Faster F. No back problems G. Use of hands for carrying H. Greater field of vision
Which are bipedal advantages? Bipedal Advantages 1. Walk further 2. Use hands for carrying 3. Greater field of vision 4. Less heat absorbed Bipedal Disadvantages 1. More difficult births 2. Slower 3. Back problems with age 4. Can not climb trees as well
What came first bipedalism or large brains? Originally thought that large brain size came first, followed by things like bipedalism, changes in diet, and changes in behavior The fossil evidence shows that bipedalism came first. The oldest fossils of hominids had cranium sizes similar to the size of apes but showed evidence of walking upright. Bipedalism ~4mya Big brains and tool use ~2.5mya
What is a hominid? Hominid Group of bipedal primates that includes humans and their extinct ancestors Missing links between humans and apes Homo sapiens Modern human species dating back to 100,000/200,000 years ago
We did NOT come from Chimps We share a common ancestor We share about 99% DNA with chimps, which means they are our closest PRIMATE relative. Common ancestor is predicted to have existed around 6-7 mya
From Lucy to us! Most hominins in the last 4 million years fit into one of two genera (plural of genus): Australopithecus or Homo. Homo sapiens Lucy was one of the first Australopithecines and her descendants eventually gave rise to other species of Australopithecus. Lucy At some point, around 2 million years ago, one of Lucy s descendant species gave rise to a new genus, Homo, with significantly larger and much more advanced brains. This is the branch that led to Neanderthals and modern humans!
Two Main Hominid Groups Genus: Australopithecus example: A. afarensis ( Lucy ) Earlier (4 1.5 MYA) More ape-like Brain size: similar to the size of chimpanzees First bipedal primates Found in Africa Genus: Homo example: H. erectus More recent (2 MYA present) More human-like Much larger brain Completely bipedal Found in Africa, Asia, and Europe
Two Main Hominid Groups Relative size of humans compared to the Australopithecine genus.
Australopithecus afarensis 3.9-3.2 MYA The Oldest of the bunch! This is LUCY
Homo neanderthalensis 200,000-28,000 years ago
Predate Homo sapiens Coexisted alongside humans Some paleo-anthropologists consider Neanderthals to be a sub-species of Homo sapiens Think they may even have been able to interbreed
Homo sapiens 100,000-200,000 to present
Homo sapiens evolved about 100,000-200,000 years ago 1 blade of grass To put that into perspective: Noon = 1 st hominids 11 pm = Neanderthals 11:30 pm = Homo sapiens
Where did hominids first evolve? East Africa
How did hominids evolve? 5-10 mya Eastern Africa becomes cooler and drier Unbroken tropical forests become a patchwork of woodland and savannah (grassland) Western and Central Africa remain more densely wooded Primates in Western and Central Africa remain in the trees **Some primates in Eastern Africa become
Bipedalism made it easier to Spot predators Travel long distances Pick fruit off trees Freed up 2 limbs *Carry food from one location to another **Use tools!
If bipedalism came first, what caused brains to increase in size? Use of 2 free limbs Constant climate change Had to be able to adapt quickly as a species or die Change in diet Early members of the Homo genus began to eat more meat Many more calories for the body than plant material Scientists propose Homo erectus was probably the first hominid to cook food using fire Helps unlock additional nutrients to be digested easier **The more calories and nutrients consumed, the more the brain can grow**
When and where did Homo sapiens evolve? Roughly 100,000-200,000 years ago, most likely in Africa
When and where did Homo sapiens evolve? So far fossil evidence also points to East Africa Genetic evidence also points to East Africa as our origin.
The Great Rift Valley Remember: There have been hundreds of fossilized hominin specimens found since the mid 1800s. The earliest hominins (Australopithecines) are only found in Africa, while members of our own genus (Homo) migrated into Europe and Asia.
Place events in order under their correct change: Geologic; Climate; Habitat & Species 1. Savanna grasslands form in East Africa 2. Central Africa is all tropical (apes are diverse) 3. East Africa became cooler & drier due to mountain range and change in ocean currents 4. West Africa remained a tropical rainforest 5. Bipedal primates evolve in East Africa 6. Great Rift Valley forms isolating East Africa & connection of North & South America