Homo sapiens

Homo sapiens is the modern human species. Homo sapiens is a name in binomial nomenclature. It means that modern humans belong to the genus Homo and the species sapiens. It is abbreviated H. sapiens.

Modern humans are the only living species of the genus Homo. There were other species in this genus (like Homo habilis and Homo erectus), but they are extinct.

Homo sapiens are sometimes called "anatomically modern humans".

Origin

370px|thumb|Schematic representation of the emergence of H. sapiens from earlier species of Homo. The horizontal axis shows geographic location; the vertical axis shows time in millions of years ago. Blue areas show presence at a given time and place.

Most scholars agree that modern humans originated in East Africa. This is the near-consensus position held within the scientific community.

The hypothesis that humans have a single origin was published in Charles Darwin's The Descent of Man (1871). Modern studies of mitochondrial DNA support this theory. So does evidence based on physical anthropology of fossil humans. 

According to genetic and fossil evidence, older versions of H. sapiens evolved only in Africa, between 200,000 and 100,000 years ago. Then members of one branch of H. sapiens left Africa by 90,000 years ago. Over time, it replaced earlier human populations such as Neanderthals and Homo erectus.

 Neanderthal genome 
Sequencing of the full Neanderthal genome suggests Neanderthals and some modern humans share some ancient genetic lineages. Some populations may have as much as 4% Neanderthal DNA, according to the authors of this study. The reason for this admixture is not known. 

This DNA overlap may exist because both Neanderthals and modern humans had a common ancestor, according to an August 2012 study.Study casts doubt on human-Neanderthal interbreeding theory, The Guardian, Tuesday 14 August 2012Anders Eriksson and Andrea Manica Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins PNAS 2012 : 1200567109v1-201200567. July 20, 2012

Evolution

The genus Homo evolved out of the last common ancestor roughly 10 to 2 million years ago. The species H. sapiens evolved from Homo erectus roughly 1.8 to 0.2 million years ago.

Scientific study of human evolution focuses mostly on how the genus Homo developed. However, it usually involves studying other hominids and hominines as well, such as Australopithecus. 

 Extinct subspecies 
Within the Homo sapiens species, modern humans belong to the only living subspecies: Homo sapiens sapiens. Homo sapiens idaltu, the other known subspecies, is now extinct.Human evolution: the fossil evidence in 3D, by Philip L. Walker and Edward H. Hagen, Dept. of Anthropology, University of California, Santa Barbara. Retrieved April 5, 2005. 

Homo neanderthalensis, which became extinct 30,000 years ago, has sometimes been classified as a subspecies, "Homo sapiens neanderthalensis". Genetic studies now suggest that the functional DNA of modern humans and Neanderthals diverged 500,000 years ago.

Similarly, some scientists have classified the discovered specimens of the Homo rhodesiensis species as a subspecies, but this classification is not widely accepted.

Earliest fossils of the species
Until recently it was thought that anatomically modern humans first appeared in the fossil record in Africa about 195,000 years ago. However, studies of molecular biology suggest that 200,000 years ago, modern humans diverged from the common ancestor of all human populations.The oldest Homo sapiens: – URL retrieved May 15, 2009 

A broad study of African genetic diversity found the ǂKhomani San people had the greatest genetic diversity among the 113 distinct populations sampled. This makes them one of 14 "ancestral population clusters". The research also placed the origin of modern human migration in south-western Africa, near the coastal border of Namibia and Angola.; the results were published in the online edition of the journal Science.

In the 1960s an archaeological site at Jebel Irhoud in Morocco was dated as about 40,000 years old. However, it was re-dated in the 2000s. It is now thought to be between 300,000 and 350,000 years old. The skull form is almost identical to modern humans,Ghosh P. 2017. First of our kind found in Morocco. BBC News Science & Environment.  though the jaw is different.

The forces of natural selection have continued to operate on human populations, with evidence that certain regions of the genome show selection in the past 15,000 years.

 Related pages 

 Evolution
 Natural selection
 Binomial nomenclature
 Homo
 Neanderthal genome project

References

Category:Hominins
Category:Humans