The origin of life
About 4.6 billion years ago, the Earth was a sphere of molten rock without a single form of life. Today, a walk along the Mississippi River or through Yellowstone shows an immense biological diversity. Between one moment and the other, a decisive transition had to take place: the step from inert matter to living matter, one of the great open problems in science.
The early Earth
Describe what early Earth was like at the time life emerged: its atmosphere, its oceans and its geological activity.
Describe what early Earth was like at the time life emerged: its atmosphere, its oceans and its geological activity.
From spontaneous generation to prebiotic synthesis
Look at the diagram of the apparatus with which Miller and Urey carried out their famous experiment in 1953. Identify what the parts labeled ?1 to ?4 represent (the gas…
Look at the diagram of the apparatus with which Miller and Urey carried out their famous experiment in 1953. Identify what the parts labeled ?1 to ?4 represent (the gas mixture, electrical discharges, boiling water and the collection trap), explain what conditions of early Earth they simulated in the laboratory and what type of molecules they obtained.
For centuries, it was believed that living organisms could arise from non-living matter: worms from decaying meat or mice from dirty clothes. Describe what the…
For centuries, it was believed that living organisms could arise from non-living matter: worms from decaying meat or mice from dirty clothes. Describe what the hypothesis of spontaneous generation consisted of, and explain how it was experimentally disproved by Redi with his jars of meat, Spallanzani with boiled broths and, above all, Pasteur with his swan-neck flasks.
Hypotheses on the origin of life
Current hypotheses on the origin of life include chemical synthesis in the "primordial soup", panspermia and hydrothermal vents on the ocean floor. Summarize them…
Current hypotheses on the origin of life include chemical synthesis in the "primordial soup", panspermia and hydrothermal vents on the ocean floor. Summarize them briefly and then order and explain the steps necessary to go from individual molecules to the first cell: appearance of hereditary material capable of copying itself, formation of complex organic molecules, appearance of metabolism and formation of membranes.
Timeline of early life
Astrobiology: the search for life beyond the Earth
Looking at the night sky and wondering whether we are alone has stopped being just a philosophical question: space telescopes are discovering thousands of exoplanets and probes are analyzing water geysers on the moons of Jupiter and Saturn; how can science determine whether life exists, or has ever existed, on any of those distant worlds?
What is astrobiology? Explain what it studies and why searching for life outside Earth helps us understand the origin of life on our planet.
What is astrobiology? Explain what it studies and why searching for life outside Earth helps us understand the origin of life on our planet.
The geosphere: the Earth's solid layers
As the early Earth cooled, its materials sorted themselves into layers. Which part of the planet is the "geosphere", and what is it made of?
Why is the search for life on other worlds so focused on finding liquid water? Explain which properties of water make it so important for living things.
Why is the search for life on other worlds so focused on finding liquid water? Explain which properties of water make it so important for living things.
Back to the beginning: The step from molten rock to the biosphere first required the planet to cool enough to hold liquid water, the prebiotic synthesis of organic monomers from inert matter, and their progressive self-assembly into vesicles with metabolism and hereditary material.