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 boundaryWhere we left off on our discussion of evolution of life on Earth…

1. Eukaryotes evolved with symbiont prokaryote-organelles (2.1 b.y.a.);

2. 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;

3. Life invaded land (475 m.y.a.);

4. Organisms developed the resistance to desiccation, and invaded the land (400 m.y.a.);

5. 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

What had happened?

Summary:

Plants and animals: 75% species loss

Plant and animal kill: 99% by individual!

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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 extinctionsOrdovician-Silurian periods

440-450 MYA: 2nd largest; claimed 27% (families), 57% (genera). Likely due to climate changes; not an impact.

Late Devonian period360-375 MYA: Part of a series, claimed 19% (families), 50% (genera), 70% (species). Instigated the arrival of amphibians.

Permian-Triassic periods251 MYA: Largest; 57% (families), 83% (genera). Opened the way for dinosaurs by removing amphibians and mammal-like reptiles.

Triassic-Jurassic periods205 MYA: 23% (families), 48% (genera).

Cretaceous-Tertiary periods65 MYA: 75% (species).

Current times1900s to 2100: 50% (species). Caused by humans. 5

The extinction that takes us outCauses:

More asteroids/comets Magnetic field reversalsSupernovae Gamma-ray burstsEcological 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 process—the techniques that have created vaccines, ipods, and spacecraft—and study the evolution of our own species.

Some basic misconceptions on (hominid) evolution– “It’s 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 evolutionAn 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 speciesT1, A. africanus, 2.6 MyT2, A. africanus, 2.5 MyT3, H. habilis, 1.9 MyT4, H. habilis, 1.8 MyT5, H. rudolfensis, 1.8 MyT6, H. erectus, 1.75 MyB1, H. ergaster (early H. erectus), 1.75 MyB2, H. heidelbergensis, 300,000 – 125,000 yB3, H. sapiens neanderthalensis, 70,000 yB4, H. sapiens neanderthalensis, 60,000 yB5, H. sapiens neanderthalensis, 45,000 yB6, H. sapiens sapiens, Cro-Magnon, 30,000 y

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We are all AfricansThe 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: EuropeH. erectus: AsiaH. 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 evolutionCultural 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 processesGenetic engineering of plants and lower organisms commonplace;Creation of artificial life in progress (Craig Venter’s 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 evolutionImpending crises approach (we shall see)

– Resource exhaustion?– Technological singularity?

Moore’s law—the # 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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