Transcript Lecture 2 - Organic Origins Debate

Life As We Know It
Genetics and the Origins of
Humankind
Humble Beginnings
Life (4000 mya)
 Bacteria (3900 mya)
 Algae (1600 mya)
 Plants (1300 mya)
 Vertebrates (510 mya)
 Mammals (114 mya)

Hominids
Primates evolved ~95 mya
 Great Rift Valley:
 separates African animal populations
 diverse ecological conditions
 Hominids diverged from Apes on border of
forested and savanna environments
 Homo sapiens sapiens ~150,000 ya

Bipedalism
Inefficient means of travel (except in
savanna)
 Knuckle-walking
 Adapted for arboreal lifestyle
 Predator avoidance
 Availability of hands
 Cooling and birthing

Origins of the Mind
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Rapid encephalisation of the brain:
 1 to 3 lb. brain in only 2 m years
Machiavellian intelligence
Climate change
Ballistic hunting
Language and group size
Sexual selection
Genetics: The Machine at Work

DNA & base pairs:
 Adenine & Thymine, Cytosine & Guanine
 Shared among all life

Genes are sequences of DNA
Build specific proteins
 Different forms of a particular gene are
called alleles

Chromosomes
Strings of genes
 23 pairs:
 23 paternal copies
 23 maternal copies
 Ordered by size (imperfectly)
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Sex Chromosomes
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X chromosome:
 All humans have at least 1 copy
 Females have 2 (homogametic)
Y chromosome:
 In humans, only males have a copy
 Males have 1 X and 1 Y (heterogametic)
 Little genetic information, “SRY”
Mendelian Heredity

Chromosomes separate (segregate) during
gamete formation

Dominant & recessive genes
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Exception: Mitochondrial DNA
Mathematics of Inheritance
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Punnett squares:
Female gametes
T
t
T
TT
Tt
t
Tt
tt
Female gametes
T
T
T
TT
TT
t
Tt
Tt
The Wrap-Up
Evolution of life on Earth
 Great Rift Valley
 Arboreal & savanna environments
 Bipedalism
 Encephalisation & origins of the mind
 DNA, genes, chromosomes (incl. sex
chromosomes)
 Mendelian heredity & Punnett squares
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Things to Come
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Problems of survival:
 Food acquisition & selection
 Habitat & environmental preferences
 Predators & environmental dangers
 Senescence