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🔗 Biology 🔗 Genetics 🔗 Computational Biology 🔗 Evolutionary biology 🔗 Human Genetic History

The last universal common ancestor (LUCA), also called the last universal ancestor (LUA), or concestor, is the most recent population of organisms from which all organisms now living on Earth have a common descent, the most recent common ancestor of all current life on Earth. (A related concept is that of progenote.) LUCA is not thought to be the first life on Earth but only one of many early organisms, all the others becoming extinct.

While there is no specific fossil evidence of LUCA, it can be studied by comparing the genomes of all modern organisms, its descendants. By this means, a 2016 study identified a set of 355 genes most likely to have been present in LUCA. (However, some of those genes could have developed later, then spread universally by horizontal gene transfer between archaea and bacteria.) The genes describe a complex life form with many co-adapted features, including transcription and translation mechanisms to convert information from DNA to RNA to proteins. The study concluded that the LUCA probably lived in the high-temperature water of deep sea vents near ocean-floor magma flows.

Studies from 2000 to 2018 have suggested an increasingly ancient time for LUCA. In 2000, estimations suggested LUCA existed 3.5 to 3.8 billion years ago in the Paleoarchean era, a few hundred million years after the earliest fossil evidence of life, for which there are several candidates ranging in age from 3.48 to 4.28 billion years ago. A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean.

Charles Darwin first proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." Later biologists have separated the problem of the origin of life from that of the LUCA.

🔗 Biology 🔗 Women's History 🔗 Anthropology 🔗 Human Genetic History 🔗 Molecular Biology 🔗 Molecular Biology/Molecular and Cell Biology 🔗 Molecular Biology/Genetics

In human genetics, the Mitochondrial Eve (more technically known as the Mitochondrial-Most Recent Common Ancestor, shortened to mt-Eve or mt-MRCA) is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman.

In terms of mitochondrial haplogroups, the mt-MRCA is situated at the divergence of macro-haplogroup L into L0 and L1–6. As of 2013, estimates on the age of this split ranged at around 155,000 years ago, consistent with a date later than the speciation of Homo sapiens but earlier than the recent out-of-Africa dispersal.

The male analog to the "Mitochondrial Eve" is the "Y-chromosomal Adam" (or Y-MRCA), the individual from whom all living humans are patrilineally descended. As the identity of both matrilineal and patrilineal MRCAs is dependent on genealogical history (pedigree collapse), they need not have lived at the same time. As of 2015, estimates of the age of the Y-MRCA range around 200,000 to 300,000 years ago, roughly consistent with the emergence of anatomically modern humans.

The name "Mitochondrial Eve" alludes to the biblical Eve, which has led to repeated misrepresentations or misconceptions in journalistic accounts on the topic. Popular science presentations of the topic usually point out such possible misconceptions by emphasizing the fact that the position of mt-MRCA is neither fixed in time (as the position of mt-MRCA moves forward in time as mitochondrial DNA (mtDNA) lineages become extinct), nor does it refer to a "first woman", nor the only living female of her time, nor the first member of a "new species".

🔗 Anthropology 🔗 Palaeontology 🔗 Extinction 🔗 Indonesia 🔗 Archaeology 🔗 Mammals 🔗 Evolutionary biology 🔗 Human Genetic History 🔗 Primates 🔗 Southeast Asia

Homo floresiensis ("Flores Man"; nicknamed "hobbit") is a pygmy archaic human which inhabited the island of Flores, Indonesia, until the arrival of modern humans about 50,000 years ago.

The remains of an individual who would have stood about 1.1 m (3 ft 7 in) in height were discovered in 2003 at Liang Bua on the island of Flores in Indonesia. Partial skeletons of nine individuals have been recovered, including one complete skull, referred to as "LB1". These remains have been the subject of intense research to determine whether they represent a species distinct from modern humans; the dominant consensus is that these remains do represent a distinct species due to genetic and anatomical differences.

This hominin had originally been considered remarkable for its survival until relatively recent times, only 12,000 years ago. However, more extensive stratigraphic and chronological work has pushed the dating of the most recent evidence of its existence back to 50,000 years ago. The Homo floresiensis skeletal material is now dated from 60,000 to 100,000 years ago; stone tools recovered alongside the skeletal remains were from archaeological horizons ranging from 50,000 to 190,000 years ago.