The protosterol biota is a group of

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s found in

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

ized fats that comprised aquatic protosterol-producing

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

and ancient deep-branching

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s from 1.6 to 0.8 billion years ago. These organisms were more complex than today's bacteria and they predate the last common ancestors of all modern eukaryotes. Perhaps they hunted their own species, since they were

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

, as they fed on other bacteria. They were present in large numbers in the aquatic environments of the seas and seriously affected the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

at the time. These

microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

s adapted to the much lower oxygen levels of the era and are also thought to have produced protosteroids. The experts from the

Australian National University The Australian National University (ANU) is a public university, public research university and member of the Group of Eight (Australian universities), Group of Eight, located in Canberra, the capital of Australia. Its main campus in Acton, A ...

and the

University of Bremen The University of Bremen () is a public university in Bremen, Germany, with approximately 18,400 students from 117 countries. Its 12 faculties offer more than 100 degree programs. The University of Bremen has been among the top 50 European rese ...

found fossils of fats that were formed 1.6 billion years ago. They found the fossils in the Barney Creek Formation in

Northern Australia The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26th parallel south, 26° and all of the Northern Territory. Those local government areas of Western Australia and Q ...

, near

Borroloola Borroloola () is a town in the Northern Territory of Australia. It is located on the McArthur River, about upstream from the Gulf of Carpentaria. Location Borroloola lies on the traditional country of the Yanyuwa people, on the coastal plain ...

, which was covered by

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

. In the findings, the researchers noticed chemical signals that suggested that the

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

s may have come from an ancestor of the last common eukaryotic ancestor from which

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s and

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

s all

evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

. The research revealed that eukaryotes already existed on Earth 1.6 billion years ago.

References

{{Reflist Precambrian paleobiotas Proterozoic life Precambrian fossils Paleoproterozoic Fossils of Australia