Archaic Homo sapiens

Homo rhodesiensis "Broken Hill Cranium": dated to either 130,000 years ago (using amino acid racemization determination) or 800,000 to 600,000 years ago (within the same time as Homo erectus), depending on which dating method is used.

A number of varieties of Homo are grouped into the broad category of archaic humans, contrasted with modern humans (Homo sapiens), in the period beginning 500,000 years ago. This category typically includes Homo heidelbergensis, Homo rhodesiensis, Homo neanderthalensis, and may also include Homo antecessor.[1]

Modern humans are theorized to have evolved from archaic humans, who in turn evolved from Homo erectus. Varieties of archaic humans are sometimes included under the binomial name "Homo sapiens" because their brain size is very similar to that of modern humans. Archaic humans had a brain size averaging 1200 to 1400 cubic centimeters, which overlaps with the range of modern humans. Archaics are distinguished from anatomically modern humans by having a thick skull, prominent brow ridges and the lack of a prominent chin.[1][2]

Anatomically modern humans appear from about 200,000 years ago and after 70,000 years ago (see Toba catastrophe theory) gradually marginalize the "archaic" varieties. Non-modern varieties of Homo are certain to have survived until after 30,000 years ago, and perhaps until as recent as 10,000 years ago. Which of these, if any, are included under the term "archaic human" is a matter of definition and varies among authors. Nonetheless, according to recent genetic studies, modern humans may have bred with "at least two groups" of ancient humans: Neanderthals and Denisovans.[3] Other studies have cast doubt on admixture being the source of the shared genetic markers between archaic and modern humans, pointing to an ancestral origin of the traits originating 500,000 to 800,000 years ago.[4][5][6]

New evidence suggests another group may also have been extant as recently as 11,500 years ago, the Red Deer Cave people of China.[7] However, Chris Stringer of the Natural History Museum in London has suggested that these people could be a result of mating between Denisovans and modern humans.[8] Other scientists remain even more skeptical, suggesting that the unique features are within the variations expected for human populations.[9]

Terminology and definition

Anatomical comparison of the skulls of anatomically modern humans "wise men" (left) and Homo neanderthalensis (right)

The category archaic human lacks a single, agreed upon definition.[1] According to one definition, Homo sapiens is a single species comprising several subspecies that include the archaics and modern humans. Under this definition, modern humans are referred to as Homo sapiens sapiens and archaics are also designated with the prefix "Homo sapiens". For example, the Neanderthals are Homo sapiens neanderthalensis, and Homo heidelbergensis is Homo sapiens heidelbergensis. Other taxonomists prefer not to consider archaics and modern humans as a single species but as several different species. In this case the standard taxonomy is used, i.e. Homo rhodesiensis, or Homo neanderthalensis.[1]

The dividing lines that separate modern humans from archaic Homo sapiens and archaics from Homo erectus are unclear. The earliest known fossils of anatomically modern humans such as the Omo remains from 195,000 years ago, Homo sapiens idaltu from 160,000 years ago, and Qafzeh remains from 90,000 years ago are recognizably modern humans. However, these early modern humans do exhibit a mix of some archaic traits, such as moderate, but not prominent, brow ridges.

Brain size expansion

The emergence of archaic humans is sometimes used as an example of punctuated equilibrium.[10] This occurs when a species undergoes significant biological evolution within a relatively short period. Subsequently, the species undergoes very little change for long periods until the next punctuation. The brain size of archaic humans expanded significantly from 900 cubic centimeters in erectus to 1300 cubic centimeters. Since the peak of human brain size during the archaics, it has begun to decline.[11]

Origin of language

Main article: Origin of language

Robin Dunbar has argued that archaic humans were the first to use language. Based on his analysis of the relationship between brain size and hominid group size, he concluded that because archaic humans had large brains, they must have lived in groups of over 120 individuals. Dunbar argues that it was not possible for Hominids to live in such large groups without using language, otherwise there could be no group cohesion and the group would disintegrate. By comparison, chimpanzees live in smaller groups of up to 50 individuals.[12][13]

Fossils

Further information: List of human evolution fossils

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 Dawkins (2005). "Archaic homo sapiens". The Ancestor's Tale. Boston: Mariner. ISBN 0-618-61916-X.
  2. ↑ Companion encyclopedia of archaeology
  3. ↑ Mitchell, Alanna (January 30, 2012). "DNA Turning Human Story Into a Tell-All". NYTimes. Retrieved January 31, 2012.
  4. ↑
  5. ↑ http://www.theguardian.com/science/2013/feb/04/neanderthals-modern-humans-research
  6. ↑
  7. ↑ Amos, Jonathan (March 14, 2012). "Human fossils hint at new species". BBC. Retrieved March 14, 2012.
  8. ↑ Barras, Colin (2012-03-14). "Chinese human fossils unlike any known species". New Scientist. Retrieved 2012-03-15.
  9. ↑ James Owen (2012-03-14). "Cave Fossil Find: New Human Species or "Nothing Extraordinary"?". National Geographic News.
  10. ↑ Alone in the Universe
  11. ↑ http://phys.org/news187877156.html
  12. ↑ CO-EVOLUTION OF NEOCORTEX SIZE, GROUP SIZE AND LANGUAGE IN HUMANS
  13. ↑ Dunbar (1993). Grooming, Gossip, and the Evolution of Language. Harvard University Press. ISBN 978-0-674-36336-6.

External links