Origin and Evolution of Life Origin and Evolution of Life on Terrestrial Planets by on Terrestrial Planets by

Brack, Hornet et al.Brack, Hornet et al.Cristina RetamozaCristina Retamoza

Richard-Jacob CoronaRichard-Jacob Corona

Overview of the Origin of Evolution Overview of the Origin of Evolution of Lifeof Life

• The paper addresses the question:

Is is possible for life to evolve on other Earth-like exoplanets that exist outside of

our Solar System?

The Precursors of LifeThe Precursors of Life

The Chemical Evolution of the The Chemical Evolution of the precursors of Lifeprecursors of Life

• Key ingredients are Organic Molecules (i.e. carbon) and Liquid Water

• Though only a small amount of amino acids are yielded

• An other possible theory is Hydrothermal vents

• A lot of Organic matter on Earth was extraterrestrial in origin.

Organic matter in the interstellarOrganic matter in the interstellarmedium and cometsmedium and comets

• Dust grains can form in to complex organic molecules or become carbonized through UV irradiation.

• Comets and Meteorites contribute to the Cosmic Dust Connection

The RNA world and RNA ancestorsThe RNA world and RNA ancestors

• Some people think that the first forms of life were cell-like in organization

• Others claim it is a step in the evolutionary process.

• PNA is a potential candidate for a prebiotic polymer.

Phylogenetic tree of lifePhylogenetic tree of life• 16s RNA Molecule diverges

into 3 domains, Archaea, Bacteria and Eukarya

• The common ancestor was likely to have been chemolithoautotrophic hyperthermophilic in nature.

• A hypothesis about life is that life appeared in a semi thermophilic environment that created catalytic reactions but was was cold enough to inhibit degradation.

Appearance of Life: Terrestrial Life Appearance of Life: Terrestrial Life as a Referenceas a Reference

for Habitable Exoplanetsfor Habitable Exoplanets

Oldest fossil recordOldest fossil record• Do to biosynthesis some scientist believe that

Earth may have been active 3.9 GYR.• These are the only places with sediments older

than 3.3 GYR

the greenstone belts of Isua in southwest Greenland,

The Barberton area east of South Africa,

The Pilbara area of northwest Australia.

The role of radiation and particle-The role of radiation and particle-induced stressinduced stress

on the evolution of lifeon the evolution of life• UV radiation can be

responsible for evolutionary processes– Selective factors against

UV– Mutations– Secondary Energetic

Particles

Environmental Limits to Extreme Environmental Limits to Extreme Life-FormsLife-Forms

• Most life forms are suited for normal environment conditions, while others can live in extreme environments.– Temperature– pH– Pressure

Points of InterestPoints of Interest• Life could of appeared as soon as there was a

stable body of water covering Earth. • Many planets are assumed to have similar

evolution to Earth, thus could have life too.

-No geodynamic process? Can live from underwater active volcanoes’ energy.

• Life had time to become complex and adapt to a diverse range of environments, so it should be hard to end it all, even if planets evolve to one extreme.

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