Thursday, July 5, 2012

Top 10 Discoveries in Human Evolution


10.  Sahelanthropus Tchadensis

sahelanthropus-tchadensis
This extinct hominid species dates back to around 7 million years ago, although its exact location on the human evolutionary tree is controversial, since it pre-dates the divergence of human and chimpanzee species and there is only one reliable specimen: a cranium known as Toumai.  Discovered in the Djurab desert of Chad between 2001 and 2002 by a team led by Michel Brunet, the enigmatic Toumai skull suggests that the species had a head similar in size to that of a chimpanzee, and was bipedal like Homo Sapiens, but had far flatter facial features.

9.  Australopithecus Afarensis

lucy
The best known individual example of this species, which lived between 3.9 and 2.9 million years ago, was discovered in 1974 at Hadar in the Awash Valley in Ethiopia by Tom Gray and Donald Johanson.  A female, the remains were christened “Lucy’” because the Beatles song, “Lucy in the Sky with Diamonds” was playing repeatedly on a tape recorder as they subsequently celebrated at their camp.  Lucy has a valgus knee, which indicates that she walked upright, a pubic arch similar to modern human females, and probably had ape-like facial features.

8.  Neanderthal Infants

neanderthal-baby
Recent research directed by the University of Oxford and the University of Cork, alongside the University of St. Petersburg, suggests that Neanderthals probably died out much earlier than had been previously thought.  The Oxford Radiocarbon Accelerator Unit allowed scientists to directly date the fossil of a Neanderthal infant found in the Mezmaiskaya cave in the northern Caucasus to 39,700 years ago, making it 10,000 years older than original research suggested.  It is now believed that any interaction between modern humans and Neanderthals would have lasted a few hundred, rather than a few thousand years, and that, in some regions, Neanderthals may have been completely extinct before modern humans moved out of Africa 65,000 years ago.

7.  Sex With Neanderthals!

sex-with-neanderthals
DNA evidence discovered by a team of scientists, led by Professor Peter Parham at Stanford University School of Medicine, suggests that modern humans who left Africa 65, 000 years ago, mated with Neanderthals and Denisovans from Europe and Asia.  This interbreeding caused genetic changes, which can still be traced in the DNA of all living humans, and also boosted our immune systems considerably.  Neanderthal and Denisovan immune system-related HLA genes represent half of such DNA in modern European and Asian populations, but only around 7 % of such DNA in modern African populations, which suggests that some modern humans carrying the new genes then returned to Africa much more recently, perhaps around 10,000 years ago.

6.  Ardi

ardi
Ardi is the moniker given to the skeletal remains of a female Ardipithecus Ramicus, who lived around 4.4 million years ago.  The oldest known and most complete hominid specimen, Ardi was discovered at Aramis, Ethiopia in 1994.  She stood four feet tall and weighed 50kg, a significantly larger specimen than Lucy.  Her remains suggest that the most recent common ancestor of chimps and humans was more human-like than previously thought, and that her society featured more pair bonding and increased involvement from parents in the lives of their offspring.

5.  Homo Rudolfensis

homo-rudolfensis
Discovered by Bernard Ngeneo in 1972 at the east side of  Lake Turkana in Kenya, this skull specimen is around 1.9 million years old, and was first thought to be representative of the Homo Habilis species.  However, its reconstructed characteristics suggested that it was actually an example of a separate contemporary species.

4.  Turkana Boy

turkana-boy
This almost-complete skeleton dates back 1.5 million years, was discovered by Kamoya Kimeu near Lake Tirkana in Kenya in 1984, and is the most complete early human skeleton ever unearthed.  Turkana Boy was around eight years old when he met his demise, and is classified as a member of the Homo Erectus or Homo Ergaster species.  At 5’3” tall, he may have reached an impressive 6’1” in adulthood and weighed in at a substantial 68kg.  He would have been capable of running to hunt prey, and had a human-like protruding nose!

3.  Peking Man

peking-man
Discovered between 1923-1927, this group of Homo Erectus skeletal specimens is dated at almost 800,000 years old, and was discovered by Johann Gunnar Andersson and Walter W. Granger.  The Peking Man remains were classified as Sinanthropus Pekinesis by Canadian Anatomist Davidson Black, but further excavations to the site finished with the Japanese invasion of 1937.  The fossils disappeared in 1941, en route from China to the USA for safekeeping, but parts of another skull were discovered at the site in 1966, and excavations re-started in 2009.

2.  Cheddar Man

cheddar-man
Discovered in 1903 in Gough’s Cave in Cheddar Gorge, Somerset, these remains date to around 7150 BC, and have a hole in the cranium which suggests that he may have met a gruesome demise.  In 1996 Brian Sykes of Oxford University successfully sequenced the mitochondrial DNA from a sample from Cheddar Man’s tooth and compared it to that of 20 living residents in nearby Cheddar Village.  One match with a single mutation was discovered, as well as two exact matches.  The mutated match was, appropriately enough, a History teacher named Adrian Targett, whilst the exact matches were two unnamed schoolchildren.  All three, in the same area, share a common ancestor in Cheddar Man.

1.  Otzi the Iceman

otzi-the-iceman
AKA Simalaun Man, Otzi is actually the well-preserved, naturally mummified remains of an individual who lived 5,300 years ago.  Found in 1991 at the Oztal Alps on the border of Austria and Italy by Helmut and Erika Simon, two German tourists from Nuremberg, Otzi was approximately 45 at the time of his demise.  He stood five-and-a-half feet tall, weighed 50kg, and analysis of the contents of his intestines revealed that his last meal consisted of red deer and herb bread.  He was also found with a copper axe, sported several carbon tattoos, and probably died as a result of a violent confrontation with rival tribesmen.


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