Eric Karsenti DE
Sunday, 23 September, 18:00-19:00
A forgotten world: The living ocean
The first forms of life (bacteria-like particles) date back to 3.8 billions years, 1.3 billion years after the birth of our planet. Since then most forms of life have been found in the oceans for billion years before appearing on land. In fact, most of the important evolutionary steps that led to complex mammals on land later on, like multicellularisation, bilateralisation, skeleton formation body plan genes, first appeared in organisms living in the oceans. This Oceanic life, in turn changed the chemistry of our atmosphere, removing most of CO2 (the original earth atmosphere was anoxic and contained more than 90% CO2) and producing oxygen through photosynthesis, allowing the eventual emergence of placental organisms. Natural selection is but one of the many parameters that drove evolution of life on earth, especially in the oceans where the whole thing started. Symbiosis, altruism, collaborative and collective behaviors, genome exchanges and complex adaptations within large ecosystems are as important. Over billion years, the chemistry, climate, geology of earth have been co-evolving with living organisms and most of this happened in the Oceans. I will show what we know today of all this beautiful story and how we are trying to better understand it, using the modern tools of molecular biology and large scale expeditions.
