Test 2 study guide
Natural selection
-
-
Charles Darwin; had a trip to the Galapagos islands; he saw high levels of variety
He was curious; He believed that earth was old and was constantly changing
The traits that help an organism survive in a particular environment are “selected” in natural
selection; he concluded that living things also change or evolve over generation; all organisms
have evolutionary adaptation; descent happens with modification Inherit characteristics that
enhance their ability to survive and reproduce.
How does it apply to human evolution? Humans and apes share many biological features;
humans and apes share a common ancestor; humans and apes should share a high percentage
of their DNA; fossils with humans and ape-like features.
o Human evolution is the lengthy process of change by which people originated from
apelike ancestors.
o Physical and behavioral traits shared by all people originated from apelike ancestors.
Evidence of the theory
-
What determines a hominid? Any human-like species, including us: Bipedal (walks on two legs):
Intelligent (large brain)
What guided change? Evolution happens when population of organisms inherit variations when
exposed to environmental changes. (adaptation)
What led to change? Climate and environmental change
What were the adaptations by humans? Development of Upright walking, development of Bipedalism, brain size was changing, mouth and dental changes, hand manipulation changes.
-1. LUCY: Lucy was discovered by Donald Johansson in Hadar, Ethiopia in 1974, Skeleton eroding
from the ancient sediment. At the time of her discovery, Lucy became the oldest fossil found!
Australopithecine afarensis.
- 2. Trail of foot prints preserved in petrified surface of a mud pan; two adults and a juvenile walking
away from a volcanic eruption; Tanzania to Serengeti plains.
-3. Mitochondrial DNA: We find that all humans alive today, including us, descended from a SINGLE
FEMALE
Ramapithe
cus and
proconsul
Ramapithecus and Proconsul
- ramapithecus: 14-16 Million Years, Earliest Ape-like ancestor, Did not walk upright; Is closely related to
Orangutan
-Proconsul: Similar in size to the chimpanzee, but stockier
- Australopithecine: A. Ramidus, A. Unamensis, A. Afarensis, A. Africanus
- Lucy belongs to the species Australopithecus afarensis, and lived 3.2 million years ago; Stood around
1.1 metres (3.5 feet) tall; Walked upright on two legs, she walked with her legs bent.
- Homo-Habilis: Discovered in the 1960’s; skull with a brain volume of about 680 cubic centimeters;
Larger than the Australopithecines; First to handle tools
- 2 - 1.5 million years - Homo habilis "handy man"; Homo rudolfensis, H. Ergaster
- Homo-erectus: Larger than H. habilis; Larger brain; Smaller face; Allowed man to "break out" of Africa
into Europe & Asia
- Homo erectus was a serious toolmaker and a fine hunter. Evidence also indicates that they
were the first to use fire.
-Homo-erectus: java Man and Pekin Man
- Homo-Neanthertalis: Not a direct ancestor - an offshoot from H. erectus; Shorter, stockier, stronger
than modern man. Adapted to ice age; Larger brain size than modern man; Buried dead with flowers first evidence of religious/symbolic thinking.
- Discovered in Neander valley Germany; Found primarily in Europe; Created innovative tools
-Homo-Sapiens (cro-Magnum): Earliest fossils found in Africa (also in Ethiopia) but also found in Europe;
Developed advanced tools; Hunted; Development of language.
- Appears to have originated from H. erectus in Africa, then migrated outwards to Europe & Asia;
Replaced existing species H. erectus & H. neanderthalis.
-Changes leading to Homo-sapiens: Larger cranial capacity and brain size; Skeletal changes
(Pelvis, jaw and spine); Bipedalism- up-right waking; Hand changes; Development of language.
What caused human evolution
- The majority of northern Africa was rainforest; Ramapithecus and Proconsul, were full arboreal apes
living in these forests.
-The great rift was created: 5 million years ago changes occurred! The great rift valley was created in
eastern Africa; What it caused? Isolate the ape population from their peers in the west; the rift also
created a “rainshadow desert” to its leeward side.
-Changes in environment: Change in rain levels changed the landscape of the region from rainforest to
savannah; Develop a new form of transportation so they evolved the ability to walk upright.
- Change in climate and environment lead to competition for resources; Hunter-gatherers;
Animals migrated out of Africa; Due to climatic change, environmental changes and animal migrations
homo erectus and homo sapiens moved out of Africa.
-Migratory routes by Cheikh anta Diop: 1.Migrated through the Sahara into the Iberian peninsula
(Europe); 2) Isthmus separating the Mediterranean sea from the red sea.
-Due to environmental and geographical location changes occurred: They migrated into Europe which
was cold so they started to have several changes in skin color and facial characteristics.
•
•
•
Africanoid- Black, brown
Mongoloid- Yellow
Caucasoid- White
-
Changes that occurred: Change in skin color (Melanin a pigment in the skin)Genetic mutation
o Facial change
o
Nasal index- Narrower nose