Destruction and creation

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Destruction and creation

• Goals
• Learn about the K-T boundary
• Asteroid impacts and mass extinctions
• Hominid evolution
• Ethics of artificial life

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The K-T boundary

• Where we left off on our discussion of evolution
  of life on Earth
• Eukaryotes evolved with symbiont
  prokaryote-organelles (2.1 b.y.a.)
• Oxygen levels and other stresses had encouraged
  the Cambrian Explosion of multicellular life (545
  m.y.a.)Biodiversity was extraordinary the
  Burgess Creek Shale (post Cambrian Explosion)
  shows arthropods from about 25 subphyla, only 4
  of which persist today
• Life invaded land (475 m.y.a.)
• Organisms developed the resistance to
  desiccation, and invaded the land (400 m.y.a.)
• Dinosaurs and mammals (245 m.y.a.).

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The K-T boundary

• 245 MYA, terrestrial biodiversity was high.
• 65 MYA, a major extinction event occurred on a
  global basis, at the end of the Cretaceous
  Period, and beginning of the Tertiary Period.
• Examples of effects

Heavy losses Microbes significant losses Marine
inverts 60 losses (genera) Terrestrial inverts
major losses Terrestrial plants huge
losses Dinosaurs extinct Ancestral birds heavy
losses Mammals moderate losses
Moderate losses Fish only 10-20 losses Fungi
benefits! Amphibians minor losses Reptiles
minor losses
Summary Plants and animals 75 species
loss Plant and animal kill 99 by individual!
What had happened?
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K-T boundary characteristics

• Global in occurrence
• High in iridium and other rare metals (osmium,
  gold, etc)
• Quartz in layer shows shock characteristics (high
  P, T)
• It contains rock droplets that were once molten
• Its carbon layers suggest soot once occurred at a
  global scale.
• Evidence suggests a gigantic meteoric impact
• Impact site Yucatán Peninsula (200 km Chicxulub
  crater)
• Object a comet or asteroid 10 km in diameter
• 100,000,000 megaton bomb (most massive human bomb
  was 50 megatons)
• Glowing debris on global scale
• Global tsunami events
• Months of smoke and ash, resulting in global
  winter
• Subsequent possible greenhouse phase
• Possible oceanic poisoning by nitrites.

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The big five mass extinctions

• Ordovician-Silurian periods
• 440-450 MYA 2nd largest claimed 27 (families),
  57 (genera). Likely due to climate changes not
  an impact.
• Late Devonian period
• 360-375 MYA Part of a series, claimed 19
  (families), 50 (genera), 70 (species).
  Instigated the arrival of amphibians.
• Permian-Triassic periods
• 251 MYA Largest 57 (families), 83 (genera).
  Opened the way for dinosaurs by removing
  amphibians and mammal-like reptiles.
• Triassic-Jurassic periods
• 205 MYA 23 (families), 48 (genera).
• Cretaceous-Tertiary periods
• 65 MYA 75 (species).
• Current times
• 1900s to 2100 50 (species). Caused by humans.

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The extinction that takes us out

• Causes
• More asteroids/comets Magnetic field reversals
• Supernovae Gamma-ray bursts
• Ecological collapse Global volcanism
• What about the next impact event? Global kill
  rate ??? ?? (families), ?? (genera).
• Our space and military programs would be unable
  to respond effectively.

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Hominid evolution

• We now take the audacious step of applying the
  same techniques throughout the scientific
  processthe techniques that have created
  vaccines, ipods, and spacecraftand study the
  evolution of our own species.
• Some basic misconceptions on (hominid) evolution
• Its just a theory
• There are no missing links
• We did not evolve from monkeys, orangutans,
  gorillas, chimpanzees, or bonobos
• Anthropologists are not in huge disagreement on
  the basic concepts of biological evolution
  (Project Steve).

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Hominid evolution

• An extensive record now exists of the development
  of humans over the last several million years.
  There are many players, and new fossils are being
  discovered frequently.
• Most new fossils are simply repeat findings of
  previously known hominids.
• Some fossil Australopithecus and Homo species
• T1, A. africanus, 2.6 My
• T2, A. africanus, 2.5 My
• T3, H. habilis, 1.9 My
• T4, H. habilis, 1.8 My
• T5, H. rudolfensis, 1.8 My
• T6, H. erectus, 1.75 My
• B1, H. ergaster (early H. erectus), 1.75 My
• B2, H. heidelbergensis, 300,000 125,000 y
• B3, H. sapiens neanderthalensis, 70,000 y
• B4, H. sapiens neanderthalensis, 60,000 y
• B5, H. sapiens neanderthalensis, 45,000 y
• B6, H. sapiens sapiens, Cro-Magnon, 30,000 y

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We are all Africans
The prevailing (but not only theory) is that
while the Earth has had a number of species of
hominids, three entities were widespread until
recently
H. sapiens neanderthalensis Europe H. erectus
Asia H. sapiens Africa It seems that Homo
sapiens sapiens emigrated from Africa, and
displaced the other species/subspecies. Note we
did not evolve from existing apes!
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Critical future mileposts in our evolution

• Cultural evolution modifies evolutionary
  processes
• Rise of agriculture
• Rise of easy transportation modifies gene flow
• Rate of cultural evolution dwarfs biological
  evolution.
• Technological evolution rules evolutionary
  processes
• Genetic engineering of plants and lower organisms
  commonplace
• Creation of artificial life in progress (Craig
  Venters Mycoplasma mycoides)
• 2014 insertion of dNaM-d5SICS (called XY)
  artificial base pair into E. coli
• Genetic engineering of humans is inevitable
• Ilya Ivanov inseminated female chimps with human
  sperm in 1927.
• He prepared to inseminate five human females
  with orangutan sperm in 1929.
• He was interrupted only by changes in Soviet
  politics.

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Critical future mileposts in our evolution

• Impending crises approach (we shall see)
• Resource exhaustion?
• Technological singularity?Moores lawthe of
  transistors on a chip doubles every two
  years.When CAD-facilitated computer
  construction reaches a point comparable to human
  intelligence, machine evolution will exceed human
  evolution.And we all know what that means

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