A protocell is a self-organized, endogenously ordered, spherical collection of lipids proposed as a rudimentary precursor to cells during the origin of life. A central question in evolution is how simple protocells first arose and how their progeny could diversify, thus enabling the accumulation of novel biological emergences over time. Although a functional protocell has not yet been achieved in a laboratory setting, the goal to understand the process appears well within reach.
Surfactant molecules arranged on an air–water interface
In biology, abiogenesis, or the origin of life, is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to living entities on Earth was not a single event, but a process of increasing complexity involving the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. The transition from non-life to life has never been observed experimentally, but many proposals have been made for different stages of the process.
Stromatolites in the Siyeh Formation, Glacier National Park, dated 3.5 Gya, placing them among the earliest life-forms
Modern stromatolites in Shark Bay, created by photosynthetic cyanobacteria
The Cat's Paw Nebula is inside the Milky Way Galaxy, in the constellation Scorpius. Green areas show regions where radiation from hot stars collided with large molecules and small dust grains called "polycyclic aromatic hydrocarbons" (PAHs), causing them to fluoresce. Spitzer Space Telescope, 2018.
The earliest known life forms are putative fossilized microorganisms, found in white smoker hydrothermal vent precipitates. They may have lived as early as 4.28 Gya (billion years ago), relatively soon after the formation of the oceans 4.41 Gya, not long after the formation of the Earth 4.54 Gya.
