Life As We Know It

1
Life As We Know It

• Genetics and the Origins of Humankind

2
Humble Beginnings

• Life (4000 mya)
• Bacteria (3900 mya)
• Algae (1600 mya)
• Plants (1300 mya)
• Vertebrates (510 mya)
• Mammals (114 mya)

3
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

4
Bipedalism

• Inefficient means of travel (except in savanna)
• Knuckle-walking
• Adapted for arboreal lifestyle
• Predator avoidance
• Availability of hands
• Cooling and birthing

5
Origins of the Mind

• 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

6
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

7
Chromosomes

• Strings of genes
• 23 pairs
• 23 paternal copies
• 23 maternal copies
• Ordered by size (imperfectly)

8
Sex Chromosomes

• 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

9
Mendelian Heredity

• Chromosomes separate (segregate) during gamete
  formation
• Dominant recessive genes
• Exception Mitochondrial DNA

10
Mathematics of Inheritance

• Punnett squares

Female gametes
Female gametes
T
T
T
t
T
T
TT
TT
TT
Tt
Male gametes
Male gametes
t
t
tt
Tt
Tt
Tt
11
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

12
Things to Come

• Problems of survival
• Food acquisition selection
• Habitat environmental preferences
• Predators environmental dangers
• Senescence