Ch22: Human Evolution

1
Ch22 Human Evolution
2
Evolution Vs. Intelligent Design

• Evolution
• Change in heritable traits within a population
  over successive generations
• Supported by scientific evidence

• Intelligent Design
• Concept that certain features of the universe
  and of living things are best explained by an
  intelligent cause
• Can not be supported or rejected by research

3
Geological Time
4
Chemical Evolution

• Atmospheric gases reacted and produces small
  organic molecules
• Stanley Miller performed an experiment to support
  this hypothesis
• Small organic molecules joined to produce organic
  macromolecules
• Organic macromolecules formed the first
  Protocell.
• Lipid-protein membrane
• Heterotroph takes in preformed food
• Fermenter- created energy without oxygen
• Protocells incorporated RNA ( then DNA) to
  create a True cell.
• Cell was able to reproduce pass on its genetic
  information.

5
(No Transcript)
6
Biological Evolution

• Biological evolution is a change in life forms
  between generations.
• Two aspects of biological evolution
• Common descent all living descended from a
  common ancestor
• Explains unity of all living things (i.e. all
  living things are made up of cells and have the
  same biochemistry)
• Adaptation modification in structure, function,
  or behavior to better suit the environment
• Explains the diversity of life

7
Charles Darwin

• A naturalist that formulated the theory of
  evolution based on the following evidence
• Biogeographical even though there were suitable
  environments for certain plants animals they
  were not distributed everywhere.
• Anatomical
• Homologous structures anatomical parts that are
  similar, but have different functions these
  anatomical similarities indicate common descent.
• Analogous structures have the same function,
  but are anatomically different thus, there is no
  common descent
• Fossils remains or traces of past life that has
  been preserved in the earths crust.

8
Homologous Structures
9
Additional Evidence

• Biochemical Evidence almost all living
  organisms use the same basic biochemical
  molecules.
• DNA genetic information
• Organisms that are closely related have a higher
  percentage of similar DNA
• Proteins same 20 amino acids
• ATP molecule for energy

10
Evolutionary Mechanisms

• Natural Selection - the process by which a
  species becomes adapted to its environment.
• Sexual Selection the process by which certain
  individuals are chosen to mate.
• Genetic Drift random changes in gene frequency
  in a population

11
Evolutionary Mechanisms

• Evolutionary Mechanisms are dependent on
• Mutations changes in chromosome structure
• Genetic Recombination changes in alleles
  combinations often due to crossing-over
• Gene flow movement of alleles of genes into or
  out of a population by migration and
  interbreeding.

12
Natural Selection

• Variation - physical variations can be passed
  from generation to generation
• Competition - the environment selects these
  better adapted members to have offspring and to
  pass on this characteristic
• Adaptation - subsequent generation include more
  individuals that are adapted in the same way to
  the environment.

13
Sexual Selection

• Intrasexual competition same sex individual
  fight to mate with females
• Intersexual competition females (or males)
  choose certain mates based on certain
  characteristics.

14
Human Evolution Humans are Primates

• Characteristics of Primates
• Grasping fingers and toes, some with opposable
  thumbs
• Well-developed brain
• Nails
• Single birth
• Extended period of parental care
• Emphasis on learned behavior
• Two Suborders
• Prosimianslemurs, tarsiers, and lorises.
• Anthropoidsmonkeys, apes, and humans

15
Evolution of Hominids

• Hominid humans Family branch
• Bipedal posture (walking on two feet)
• Flat face
• Brain size
• Australopithecines - a group of individuals that
  evolved and diversified in Africa.
• Hominids lived about 3 MYA
• Walked erect
• Small brain compared to us, but large brain
  compared to other primates
• Limb proportions are ape-like

Australopithecus africanus with its large brain
is the best ancestral candidate for early Homo
16
Evolution of Homo

• Homo habilis - may be the ancestor to modern
  humans (2.0-1.9 MYA)
• Made tools
• Large brain
• Dentition
• Omnivores (plant gatherers and hunters)
• May have had the rudiments of a culture
• Homo erectus may have evolved from Homo habilis
  (1.9 -.3 MYA)
• Large brain
• Striding gait
• Made well-fashioned tools
• Control of fire
• Migrated into Europe and Asia

17
Evolution of Modern Humans

• Multiregional Continuity Hypothesis evolution
  of modern humans was essentially similar in many
  different places.
• Out-of-Africa Hypothesis evolution of H.sapiens
  evolved from H.erectus only in Africa and then
  H.sapiens migrated to Europe Asia

18
We are one Species

• Biological definition of a species Any group of
  organisms able to interbreed and bear fertile
  offspring.