The Origin and Maintenance of Life Nicolas Kosoy

Outline What is life? – John Maynard Smith on Life and Evolution Why living systems are important to us? Conclusions

What is Life? John Maynard Smith-Origin of Life –

Origin of Life (Theories, Oparin: 1924) Theory of Spontaneous Generation – “Maggots in rotting meat … are generated spontaneously from decaying materials” Theory of Panspermia – Cosmozoa cast off by celestial bodies carried germs of microorganisms Primordial Soup

Origin of Life (replication) Replication of molecules in the absence of proteins – How did it happen? Imagine a molecular quasi-species (replicating RNA without recombination but with mutation, leading to different traits) – If mutation is very high, then population is a random collection of sequences – If mutation is low, the population would be centred around optimal mutation

Hypercycles (Maynard-Smith, 1979) Replicate the message GSTQ Assuming a count of 5bits per letter, leading to 75 bits in total, a max of 25 bits per word and an error of 1/50 per bit

Hypercycles (cont.) Organisation will then arise by gradual differentiation of a single quasi-species into two or more; Selection process will favour mutations making the hypercycle more efficient Compartmentalization of hypecycles in membranes

Characteristics of Life (Maynard-Smith, 1999) Genotype and phenotype are clearly distinct, separating replication from development; The genetic system is capable of transmitting an indefinitely large number of different message; There is no one-to-one mapping between particular nucleotides, codons or genes and particular parts of the body; Heredity is digital and not analog; Development is symbolic

“It is tempting to argue that these features are necessary for the evolution of complex organisms, and will turn out to be true of any that have evolved elsewhere in the universe. But this may merely reflect the fact that we lack the ability to imagine a world fundamentally different from the one we know.” (Maynard- Smith, 1999: 398)

Why living systems are important? The economy grows within the finite and non growing ecosystem, there is an opportunity cost to growth; The costs arise because the economy is a dissipative structure sustained by a metabolic flow from and back to the environment – This flow, called “throughput”, begins with the depletion of low-entropy useful resources from the environment and ends with the return of high- entropy polluting wastes (Daly, 2006)

Why…? (cont) If the throughput remains within the natural capacity of the ecosystem to absorb wastes and regenerate resources, then the scale of the economy is considered “sustainable”; – Nonrenewable resources cannot be exploited in a sustainable- yield manner; – Uncertainty about what exploitation levels sustainable, gives rise to the “precautionary principle”

Why…? (cont) As growth pushes us from an empty world to a full world, the limiting factor in production will increasingly become natural capital The identity of the limiting factor changes from manmade to natural capital – economizing efforts and policies must change accordingly – becomes more important to study the nature of environmental goods and services

Conclusions Life is an evolutionary process taking place over hundreds of millions of years and whose main characteristics are function and natural selection; Information is passed from on generation to the other, but there is no matching between the information that passes and the information exhibited by one generation; Life is the origin of the economic process, degrading life also implies the degradation of value

Conclusions Living systems define a hard limit to our social metabolism; Non linearity and uncertainty are inherent conditions of all living systems; Managing living systems does not mean simplifying them but understanding the relationships between variables and trade-offs between outcomes.

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