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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 - PowerPoint PPT Presentation
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Life As We Know ItLife As We Know It
Genetics and the Origins of Humankind
Humble BeginningsHumble BeginningsLife (4000 mya)Bacteria (3900 mya)Algae (1600 mya)Plants (1300 mya)Vertebrates (510 mya)Mammals (114 mya)
HominidsHominidsPrimates evolved ~95 myaGreat 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
Inefficient means of travel (except in savanna)
Knuckle-walkingAdapted for arboreal lifestylePredator avoidanceAvailability of handsCooling and birthing
BipedalismBipedalism
Rapid encephalisation of the brain: 1 to 3 lb. brain in only 2 m years
Machiavellian intelligenceClimate changeBallistic huntingLanguage and group sizeSexual selection
Origins of the MindOrigins of the Mind
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
Genetics: The Machine at Genetics: The Machine at WorkWork
ChromosomesChromosomesStrings of genes23 pairs:
23 paternal copies 23 maternal copies
Ordered by size (imperfectly)
Sex ChromosomesSex ChromosomesX 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 HeredityMendelian HeredityChromosomes separate (segregate)
during gamete formation
Dominant & recessive genes
Exception: Mitochondrial DNA
Mathematics of InheritanceMathematics of InheritancePunnett squares:
Female gametes
Male
gam
ete
s T
T
T
Female gametes
Male
gam
ete
s T
T
t
t t
TT TT TT
tt
Tt
Tt Tt Tt
The Wrap-UpThe Wrap-UpEvolution of life on EarthGreat Rift ValleyArboreal & savanna environmentsBipedalismEncephalisation & origins of the mindDNA, genes, chromosomes (incl. sex
chromosomes)Mendelian heredity & Punnett squares
Things to ComeThings to ComeProblems of survival:
Food acquisition & selection Habitat & environmental preferences Predators & environmental dangers Senescence