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SOC111 
Introduction to Anthropology 
EVOLUTION AND 
GENETICS
Evolution and Genetics 
• What is evolution, and how does it occur? 
• How does heredity work, 
and how is it studied? 
• What forces contribute 
to genetic evolution?
Evolution 
• Humans have uniquely varied 
ways—cultural and biological—of 
adapting to environmental stresses 
• Many scholars became interested in 
biological diversity and our position 
within the classification of plants 
and animals during the 18th century
Evolution 
• Creationism: biological similarities and 
differences originated at the Creation 
• Linnaeus (1707–1778) developed 
the first comprehensive and still 
influential classification, or 
taxonomy, of plants and animals 
• He grouped life forms on the basis of 
differences and similarities in physical 
characteristics. 
– Fossil discoveries during the 18th and 19th 
centuries raised doubts about creationism
• If all life originated at the same 
time, why aren’t ancient species 
still around? 
• Why weren’t contemporary plants 
and animals found in fossil 
records?
• Catastrophism: a modified 
version of creationism that 
accounts for the fossil record by 
positing divinely authored 
worldwide disasters that wiped 
out creatures represented in the 
fossil record.
Theory and Fact 
• Evolution (descent with modification): an 
alternative to creationism and 
catastrophism was transformism 
• Species arise from others through a long 
and gradual process of transformation. 
• Charles Darwin is the 
best known of evolutionists
• Darwin influenced by 2 people: 
– Grandfather, Erasmus Darwin, who 
proclaimed a common ancestry of all animal 
species 
– Lyell’s principle of Uniformitarianism: 
The present is the key to the past; 
explanations for past events should be sought 
in the long-term action of ordinary forces that 
still operate today.
• Natural forces (rain, earthquakes, volcanic 
eruptions) have gradually built and modified 
geological features (such as mountain ranges). 
• Cappadocia
– Uniformitarianism cast doubt on the 
belief that the world was only 6000 
years old. It would take much longer 
for ordinary forces such as rain and 
wind to produce major geological 
changes. 
– Theory of evolution 
• Theory: a set of ideas formulated to 
explain something 
Darwin applied uniformitarianism and 
long-term transformation to living 
things and argued that all life forms are 
related and the number of species 
have increased over time.
• Natural selection: the process by which 
the forms most suited to survive and 
reproduce in a given environment do so in 
greater numbers. 
• More than survival of the fittest, natural 
selection is differential reproductive 
succes.
• When there’s a food shortage, 
those with longer necks have 
an advantage 
• If this feeding 
advantagepermits longer-necked 
giraffes to survive and 
reproduce more effectively, 
then they will transmit more of 
their genetic material to future 
generations than will those with 
shorter necks.
Evolution 
• Physical development of the individual, not 
species. (babies of weight lifters) 
• Evolution works as the process of 
natural selectiontakes advantage 
of the variety that is already 
present in a population.
Genetics 
• Genetic science helps us understand the 
causes of biological variation 
– Mendelian genetics: studies the 
ways in which chromosomes 
transmit genes across generations 
– Biochemical genetics: examines structure, 
function, and changes in DNA 
– Population genetics: investigates 
natural selection and the causes of genetic 
variation, stability, and change
Mendel’s experiments 
• Austrian monk Gregor Mendel 
began a series of experiments that 
revealed the basic principle of 
genetics in 1856 
– Studied inheritance of seven 
contrasting traits in pea plants 
– Discovered that heredity is determined 
by discrete particles or units
Mendel’s experiments 
• Concluded that a dominant form 
could mask another form in hybrid 
individuals, without destroying the 
recessive trait 
• Basic genetic units Mendel described were 
factors (now called genes or alleles) that 
are located on chromosomes
Mendel’s experiments 
• Chromosome: a paired length 
of DNA, composed of multiple genes 
• Gene: a place (locus) on a 
chromosome that determines a 
particular trait 
• Allele: a variant to a particular gene
Mendel’s experiments 
• Independent Assortment and Recombination 
– Independent Assortment: chromosomes 
are inherited independently of one another 
– Recombination: the combination of genetic 
traits in an offspring; this process creates new 
types on which natural selection can operate
Biochemical, or Molecular, 
Genetics 
• Mutation: changes in the DNA 
molecules of which genes and 
chromosomes are built 
• Gametes: sex cells that 
make new generations
Biochemical, or Molecular, 
Genetics 
• DNA: initiates 
and guides the construction of 
hundreds of proteins necessary for 
bodily growth, maintenance, and 
repair.
Cell Division 
• Mitosis: ordinary cell division, wherein 
one cell splits to form two identical cells 
• Meiosis: the special process by which sex 
cells are produced 
– Four cells 
produced from one 
– Each cell carries 
half the genetic 
material of the original 
cell 
– Fertilization allows the 
products of meiosis 
from one parent to 
recombine with those 
from the other parent 
– Chromosomes 
sort independently
Crossing Over 
• Crossing over: the process wherein 
homologous chromosomes exchange 
segments by breakage and 
recombination 
– Can occur with any chromosome pair 
– An important source of variety
Mutation 
• Base substitution mutation: substitution of 
one base in a triplet by another 
– If mutation occurs in a sex cell, the new 
organism will carry mutation in every cell 
• Chromosomal rearrangement: pieces 
of a chromosome break off and reattach 
someplace else on that chromosome
Mutation 
• Approximately three mutations will occur in 
every sex cell 
– Most mutations are neutral 
– Evolution depends on mutations 
– Variants produced through mutation 
can be especially significant if there 
is a change in environment
Population Genetics and 
Mechanisms of Genetic Evolution 
• Population genetics studies 
stable and changing populations 
– Gene pool: alleles and genotypes 
within breeding population 
– Genetic evolution: the change in allele 
frequency in a breeding population
Natural Selection 
• Genotype: the genetic makeup of an 
organism 
• Phenotype: an organism’s evident 
biological traits 
– Natural selection acts only on phenotypes 
– Human biology has considerable plasticity 
– The environment works on 
a genotype to build a phenotype
3 Different Ways of Natural 
Selection 
1.Directional Selection 
2.Sexual Selection 
3.Stabilizing Selection
Directional Selection 
• After several generations of 
selection, gene frequencies change 
– Adaptive: favored by natural selection 
– Directional selection continues as long 
as environmental sources stay the same 
– Humans do not have to delay adaptation until 
a favorable mutation occurs
Sexual Selection 
• Selection also operates 
through competition for mates 
• Sexual selection: based on 
differential success in mating; a selection 
of traits that enhances mating success
Stabilizing Selection 
• Balanced 
polymorphism: the 
frequencies of two or 
more alleles of a gene 
remain constant from 
generation to generation
Random Genetic Drift 
• Random genetic drift: loss 
of alleles from a population’s 
gene pool through chance 
– Lost alleles can reappear in the 
gene pool only through mutation 
– Fixation, the replacement, for example, 
of blue eyes by brown eyes, 
is more rapid in small populations
Gene Flow 
• Gene flow: exchange of genetic material 
between populations of the same species 
– Alleles spread through gene flow even when 
selection not operating on the allele 
– Species: group of related organisms whose 
members can interbreed to produce offspring 
that live and reproduce 
– Gene flow tends to prevent 
speciation: the formation of new species
RECAP OF LAST CLASS 
• In the 18th century, Carolus Linnaeus developed 
biological taxonomy. He viewed similarities and 
differences among organisms as part of God’s 
orderly plan rather than as evidence for 
evolution. 
• Charles Darwin proposed that natural selection 
could explain the origin of species, biological 
diversity and similarities among related life 
forms. Natural selection requires variety in the 
population undergoing selection.
RECAP OF LAST CLASS 
• Through breeding experiments with peas in 1856, 
Gregor Mendel discovered that genetic traits 
pass on as units which are known as 
chromosomes. He also formulated the law of 
independent assortment. Each of seven traits he 
studied in peas was inherited independently of all 
others. Independent assortment of chromosomes 
and their recombination provide some of the 
variety needed for natural selection. But the 
major source for such variety is mutation, an 
alteration in the DNA molecules of which genes 
are made.
RECAP OF LAST CLASS 
• Genetics studies structure, function and changes in 
genetic material-DNA. 
• Genetic changes that provide variety within a 
population include base substitution mutations, 
chromosomal rearrangements and genetic 
recombination. 
• Natural selection is the most important mechanism of 
evolutionary change. Others include random genetic 
drift and gene flow. 
• Natural selection work for characteristics already 
present in a population. If variety is insufficient for 
adaptation to environmental change, extinction 
happens.
The Modern Synthesis 
• Currently accepted view of evolution: 
– Microevolution: small-scale changes in 
allele frequencies over just a few 
generations 
– Macroevolution: large-scale changes in 
allele frequencies in a population 
over a longer time period that result in the 
formation of new species.
The Modern Synthesis 
• Punctuated equilibrium: long 
periods of stasis may be 
interrupted by evolutionary leaps 
– Sudden environmental change 
offers possibility for the pace of 
evolutions to speed up 
– Although species can survive 
radical environmental shifts, 
extinction is more common
Extinctions of Earth 
• The earth has witnessed several mass 
extinctions. 
• The biggest one Palezoic Period to 
Masezoic Period 
245 million years ago 
5 million species on earth 4.5 m. species died
Extinctions of Earth 
• The second biggest extinction 
– 65 million years ago 
– Extinction of dinasours 
– One explanation: long-lasting cloud of gas and 
dust arose from the impact of a giant meteorite at 
the end of the mesozoic period. The cloud blocked 
solar radiation and photosynthesis, ultimately 
destroying more plants and the chain of animals 
that fed on them.

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Evolution and Genetics

  • 1. SOC111 Introduction to Anthropology EVOLUTION AND GENETICS
  • 2. Evolution and Genetics • What is evolution, and how does it occur? • How does heredity work, and how is it studied? • What forces contribute to genetic evolution?
  • 3. Evolution • Humans have uniquely varied ways—cultural and biological—of adapting to environmental stresses • Many scholars became interested in biological diversity and our position within the classification of plants and animals during the 18th century
  • 4. Evolution • Creationism: biological similarities and differences originated at the Creation • Linnaeus (1707–1778) developed the first comprehensive and still influential classification, or taxonomy, of plants and animals • He grouped life forms on the basis of differences and similarities in physical characteristics. – Fossil discoveries during the 18th and 19th centuries raised doubts about creationism
  • 5. • If all life originated at the same time, why aren’t ancient species still around? • Why weren’t contemporary plants and animals found in fossil records?
  • 6. • Catastrophism: a modified version of creationism that accounts for the fossil record by positing divinely authored worldwide disasters that wiped out creatures represented in the fossil record.
  • 7. Theory and Fact • Evolution (descent with modification): an alternative to creationism and catastrophism was transformism • Species arise from others through a long and gradual process of transformation. • Charles Darwin is the best known of evolutionists
  • 8. • Darwin influenced by 2 people: – Grandfather, Erasmus Darwin, who proclaimed a common ancestry of all animal species – Lyell’s principle of Uniformitarianism: The present is the key to the past; explanations for past events should be sought in the long-term action of ordinary forces that still operate today.
  • 9. • Natural forces (rain, earthquakes, volcanic eruptions) have gradually built and modified geological features (such as mountain ranges). • Cappadocia
  • 10. – Uniformitarianism cast doubt on the belief that the world was only 6000 years old. It would take much longer for ordinary forces such as rain and wind to produce major geological changes. – Theory of evolution • Theory: a set of ideas formulated to explain something Darwin applied uniformitarianism and long-term transformation to living things and argued that all life forms are related and the number of species have increased over time.
  • 11. • Natural selection: the process by which the forms most suited to survive and reproduce in a given environment do so in greater numbers. • More than survival of the fittest, natural selection is differential reproductive succes.
  • 12. • When there’s a food shortage, those with longer necks have an advantage • If this feeding advantagepermits longer-necked giraffes to survive and reproduce more effectively, then they will transmit more of their genetic material to future generations than will those with shorter necks.
  • 13. Evolution • Physical development of the individual, not species. (babies of weight lifters) • Evolution works as the process of natural selectiontakes advantage of the variety that is already present in a population.
  • 14. Genetics • Genetic science helps us understand the causes of biological variation – Mendelian genetics: studies the ways in which chromosomes transmit genes across generations – Biochemical genetics: examines structure, function, and changes in DNA – Population genetics: investigates natural selection and the causes of genetic variation, stability, and change
  • 15. Mendel’s experiments • Austrian monk Gregor Mendel began a series of experiments that revealed the basic principle of genetics in 1856 – Studied inheritance of seven contrasting traits in pea plants – Discovered that heredity is determined by discrete particles or units
  • 16. Mendel’s experiments • Concluded that a dominant form could mask another form in hybrid individuals, without destroying the recessive trait • Basic genetic units Mendel described were factors (now called genes or alleles) that are located on chromosomes
  • 17. Mendel’s experiments • Chromosome: a paired length of DNA, composed of multiple genes • Gene: a place (locus) on a chromosome that determines a particular trait • Allele: a variant to a particular gene
  • 18. Mendel’s experiments • Independent Assortment and Recombination – Independent Assortment: chromosomes are inherited independently of one another – Recombination: the combination of genetic traits in an offspring; this process creates new types on which natural selection can operate
  • 19. Biochemical, or Molecular, Genetics • Mutation: changes in the DNA molecules of which genes and chromosomes are built • Gametes: sex cells that make new generations
  • 20. Biochemical, or Molecular, Genetics • DNA: initiates and guides the construction of hundreds of proteins necessary for bodily growth, maintenance, and repair.
  • 21. Cell Division • Mitosis: ordinary cell division, wherein one cell splits to form two identical cells • Meiosis: the special process by which sex cells are produced – Four cells produced from one – Each cell carries half the genetic material of the original cell – Fertilization allows the products of meiosis from one parent to recombine with those from the other parent – Chromosomes sort independently
  • 22. Crossing Over • Crossing over: the process wherein homologous chromosomes exchange segments by breakage and recombination – Can occur with any chromosome pair – An important source of variety
  • 23. Mutation • Base substitution mutation: substitution of one base in a triplet by another – If mutation occurs in a sex cell, the new organism will carry mutation in every cell • Chromosomal rearrangement: pieces of a chromosome break off and reattach someplace else on that chromosome
  • 24. Mutation • Approximately three mutations will occur in every sex cell – Most mutations are neutral – Evolution depends on mutations – Variants produced through mutation can be especially significant if there is a change in environment
  • 25. Population Genetics and Mechanisms of Genetic Evolution • Population genetics studies stable and changing populations – Gene pool: alleles and genotypes within breeding population – Genetic evolution: the change in allele frequency in a breeding population
  • 26. Natural Selection • Genotype: the genetic makeup of an organism • Phenotype: an organism’s evident biological traits – Natural selection acts only on phenotypes – Human biology has considerable plasticity – The environment works on a genotype to build a phenotype
  • 27. 3 Different Ways of Natural Selection 1.Directional Selection 2.Sexual Selection 3.Stabilizing Selection
  • 28. Directional Selection • After several generations of selection, gene frequencies change – Adaptive: favored by natural selection – Directional selection continues as long as environmental sources stay the same – Humans do not have to delay adaptation until a favorable mutation occurs
  • 29. Sexual Selection • Selection also operates through competition for mates • Sexual selection: based on differential success in mating; a selection of traits that enhances mating success
  • 30. Stabilizing Selection • Balanced polymorphism: the frequencies of two or more alleles of a gene remain constant from generation to generation
  • 31. Random Genetic Drift • Random genetic drift: loss of alleles from a population’s gene pool through chance – Lost alleles can reappear in the gene pool only through mutation – Fixation, the replacement, for example, of blue eyes by brown eyes, is more rapid in small populations
  • 32. Gene Flow • Gene flow: exchange of genetic material between populations of the same species – Alleles spread through gene flow even when selection not operating on the allele – Species: group of related organisms whose members can interbreed to produce offspring that live and reproduce – Gene flow tends to prevent speciation: the formation of new species
  • 33. RECAP OF LAST CLASS • In the 18th century, Carolus Linnaeus developed biological taxonomy. He viewed similarities and differences among organisms as part of God’s orderly plan rather than as evidence for evolution. • Charles Darwin proposed that natural selection could explain the origin of species, biological diversity and similarities among related life forms. Natural selection requires variety in the population undergoing selection.
  • 34. RECAP OF LAST CLASS • Through breeding experiments with peas in 1856, Gregor Mendel discovered that genetic traits pass on as units which are known as chromosomes. He also formulated the law of independent assortment. Each of seven traits he studied in peas was inherited independently of all others. Independent assortment of chromosomes and their recombination provide some of the variety needed for natural selection. But the major source for such variety is mutation, an alteration in the DNA molecules of which genes are made.
  • 35. RECAP OF LAST CLASS • Genetics studies structure, function and changes in genetic material-DNA. • Genetic changes that provide variety within a population include base substitution mutations, chromosomal rearrangements and genetic recombination. • Natural selection is the most important mechanism of evolutionary change. Others include random genetic drift and gene flow. • Natural selection work for characteristics already present in a population. If variety is insufficient for adaptation to environmental change, extinction happens.
  • 36. The Modern Synthesis • Currently accepted view of evolution: – Microevolution: small-scale changes in allele frequencies over just a few generations – Macroevolution: large-scale changes in allele frequencies in a population over a longer time period that result in the formation of new species.
  • 37. The Modern Synthesis • Punctuated equilibrium: long periods of stasis may be interrupted by evolutionary leaps – Sudden environmental change offers possibility for the pace of evolutions to speed up – Although species can survive radical environmental shifts, extinction is more common
  • 38. Extinctions of Earth • The earth has witnessed several mass extinctions. • The biggest one Palezoic Period to Masezoic Period 245 million years ago 5 million species on earth 4.5 m. species died
  • 39. Extinctions of Earth • The second biggest extinction – 65 million years ago – Extinction of dinasours – One explanation: long-lasting cloud of gas and dust arose from the impact of a giant meteorite at the end of the mesozoic period. The cloud blocked solar radiation and photosynthesis, ultimately destroying more plants and the chain of animals that fed on them.