Gaia Hypothesis

Parto Siavosh

Signs of life in organisms:

• Eating

• Urination and defecation

• Motility

• Reproduction

• Ability to Response to stimulants

Lynn margulis

Is our planet alive?

1- WHAT IS “GAIA”?

2- WHAT DOES THE THEORY SUGGEST?

3- CRITICISMS

Headlines

• Gaia= land, mother

• Greek primal Greek primal goddessgoddess

• Mother nature, mother of earth

Gaia theory proposes that organisms interact with their inorganic surroundings on Earth to form a self-regulating, complex system that contributes to maintaining the conditions for life on the planet.

Gaia posits that the Earth is a self-regulating system involving : the biosphere, the atmosphere, the hydrosphere and the pedosphere, tightly coupled as an evolving system. This system as a whole -(called Gaia)- seeks a physical and chemical environment optimal for contemporary life.

The scientifically accepted form of the hypothesis :"influential Gaia” states the biota influence certain aspects of the abiotic world, e.g. temperature and atmosphere.

They state the evolution of life and its environment may affect each other. e.g. how the activity of photosynthetic bacteria during Precambrian times have completely modified the Earth atmosphere to turn it aerobic, and as such supporting evolution of life.

Evidence? Ocean salinity

Volcanic activity

Earth surface temperature

Regulation of oxygen in the atmosphere

Processing of carbon dioxide

Daisyworld model

criticism

Lack of scientific evidence

Gaia theory is a metaphor not a mechanism

Experiments with predictable results

Ice ages? High climate instability?

Gaia philosophy is a broadly inclusive term for related concepts that living organisms on a planet will affect the nature of their environment in order to make the environment more suitable for life. This set of theories holds that all organisms on a life-giving planet regulate the biosphere to the benefit of the whole. Gaia concept draws a connection between the survivability of a species and its usefulness to the survival of other species.

Gaia philosophy