The Earth is currently the only place where life is known to exist and prevailing opinion suggests that it emerged rapidly within the first billon years following planetary accretion. Complex and intelligent life is the result of a long history of biological evolution that has developed in tandem with coupled atmosphere-ocean-deep Earth processes throughout the geological record. These billion-year timescales, culminating in the modern advanced society that we have today may or may not be typical for the development of comparable and potentially habitable planets elsewhere in the Universe. Delivering a full picture of the co-evolution of the Earth and life, and their interdependence, requires integration of data and research from diverse disciplines including astronomy, astrobiology, (micro)biology, (prebiotic) chemistry and the earth- and planetary sciences. Here we identify three important steps, all based on deep understanding of both planetary and biological evolution, necessary to provide new breakthroughs in constraining the conditions necessary for the development of habitable Earth-like planets and in understanding how life originated and evolved:
- Determining the starting point for life on Earth. Constraining the processes under which Earth-like planets accreted and evolved and investigating the role of their composition. Detection and identification of abiotic sources of organic molecules that can serve as building blocks of life. Demonstrating how life can begin from a mixture of organic molecules and minerals that may have acted as templates, and establishing the environments in which this was possible. These areas all relate to defining the boundary conditions under which life could begin and unveiling the process through which life emerged.
- Identifying the earliest life forms and their metabolisms. Determining reliable biosignatures to find traces of life in ancient rocks. Tracking and understanding the evolution of life from primitive single celled organisms to communities of more advanced multicellular life. Resolving the persistence and development of life in interplay with planetary evolution and across global catastrophic events such as impacts, climate change, magnetic field excursions, large-scale volcanism, or global climatic changes. These research areas both trace the composition and extent of the biosphere and constrain the geological record back through time, from the present day to the earliest preserved materials on Earth, aiming to understand how early life and its geological environment evolved through the complex interplay between life and environment.
- Determining large-scale links between the biosphere, atmosphere, hydrosphere and geosphere throughout the geological record to the present day. Resolving the role of geological and deep geophysical processes versus shallow environmental processes in controlling near-surface environmental conditions and the evolution of life. These areas aim to better constrain the interdependency between the physical-chemical planetary and biological evolution across a range of timescales.
Understanding the interplay between life and its planetary environment on earth will allow for a more informed search for life on other planets, while understanding the origin of life on earth will answer a very profound question that resonates strongly with the general public: “Where do we all come from?”.