Origins

Abiogenesis Origin of life from non-living components.

Louis Pasteur and the death of Spontaneous Generation 1822-1899 France Experiment in 1864

Darwin’s speculation Febr 1st My dear Hooker I return the pamphlets, which I have been very glad to read.— It will be a curious discovery if Mr. Lowne’s observation that boiling does not kill certain moulds is proved true; but then how on earth is the absence of all living things in Pasteur’s experiment to be accounted for? I am always delighted to see a word in favour of Pangenesis, which some day, I believe, will have a resurrection. Mr Dyers paper strikes me as a very able Spencerian production. It is often said that all the conditions for the first production of a living organism are now present, which could ever have been present.— But if (& oh what a big if) we could conceive in some warm little pond with all sorts of ammonia & phosphoric salts,—light, heat, electricity &c present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present day such matter wd be instantly devoured, or absorbed, which would not have been the case before living creatures were formed.— Henrietta makes hardly any progress, & God knows when she will be well. I enjoyed much the visit of you four Gentlemen, ie after the Saturday night, when I thought I was quite done for. Yours affecy | C. Darwin

Alexander Ivanovich Oparin The Origin of Life (1924) Life and nonlife not very different chemically and physically Necessary chemical components from early reducing atmosphere 1894-1980; Russia

J. B. S. Haldane The Origin of Life (1929) Early abiogenesis came about by solar energy together with carbon dioxide, ammonia, and water allowing the combination of organic molecules leading to life 1892-1964, UK and India

Organic molecules are easily destroyed in oxidizing environments. Because most molecules of life are biopolymers, how were the units made and then organized into chains? e.g. amino acids into proteins, sugars into carbohydrates, nucleotides into nucleic acids, and fatty acids into lipids At what point did chemical evolution become biological evolution?

Urey and Miller Stanley Lloyd Miller Chemistry 1930-2007, USA Harold Clayton Urey Physical Chemistry 1893-1981, USA

Urey-Miller Experiment and test of the Haldane-Oparin Hypothesis, 1953

Sidney Walter Fox and Proteinoid Spheres 1912-1998, USA biochemist

Age of the Earth and Traces of Early Life Earth-Moon system formed 4.5- 4.6 BYA Period of Great Bombardment ends 4.0 BYA Evidence of a liquid ocean soon after First evidence of life 3.7 BYA Stromatolite from Glacier National Park; 3.5 BYA

Atmosphere of early earth based on similar planets Mainly carbon dioxide and nitrogen Little or no methane or ammonia

Other sources of organics Could have been major source of water and organic matter on the planet

How did organics interact to form cells? The primordial soup would have been too thin for reactions to occur.

alternatives: On clay particles Under ice Wet-dry mud of a shallow ephemeral pond.

Black Smokers

White Smokers Cooler than black smokers Tubes in white smoker chimneys approximately same size as a cell Organics present in the smoker

Gunter Wachtershauser Iron-Sulfur world provided an inorganic form of metabolism 1938- German Chemist

RNA World Proposed by Francis Crick and others Experimental work by Cech on enzymatic activity of RNA molecules 1982- Attractive because one molecule can be an enzyme and information storage molecule 1947- US Chemist

Panspermia Occur in space feeding and moved by radiation pressure from stars Comets as sources and delivery mechanisms Life-carrying material ejected from near-by planets on which life has already evolved (e.g. ALH 84001)

LUCA Once established, life quickly sequestered energy compounds and food molecules Wiped out all other incipient forms of life All living things today had a last universal common ancestor