Friday, October 18, 2013

Nothing but the Homo erectus with strong individual differences - Heise Newsticker

Andrea Naica Loebell 18/10/2013

In recent decades, the textbooks of anthropology have been constantly rewritten, because the human family tree looks much more complicated and branched out was long assumed. Many questions are still open, and now a group of scientists comes with a thesis that will surely trigger fierce debate is again: Two million years ago, it should not have been more different species of the genus Homo , but only one species earlier man with large individual differences.

all humans living today belong to the species Homo sapiens , and they vary greatly in appearance. This is, of course, for us and for all skeletal remains that are younger than 25,000 years, anthropologists as well as, of course, assuming that they have a right to anatomically modern humans.


the more violent the opposition as ten years ago on the Indonesian island of Flores, the very small human bones were found, which was arranged by their discoverers as a new species called Homo floresiensis . Just a meter tall were these “hobbits” who had very small brains, and lived until 18,000 years ago. Many experts declared the former tiny islanders immediately for malformed anatomically modern humans – as evidenced by other findings proved increasingly unlikely (hobbit ancestors)


In archaic human forms that lived millions of years, the classification is much more difficult because often only certain parts of skeletons are found, incomplete skull fragments. Assign the fossils to get an overall picture and to define from the different individuals of a species, is a major challenge for anthropology dar.

computer reconstruction of the five Dmanisi skull (Background: landscape in Dmanisi); Picture: Marcia Ponce de León and Christoph Zollikofer, University of Zurich, Switzerland

in Georgia and not in evolution Treasure Chest East Africa, where the human family tree ever expanding discoveries are made (Lucy slaughter), dig paleoanthropologists since the 1990s, nearly two million years petrified from human bone. In 85 km south of the capital Tbilisi Dmanisi lying alongside other skeletal parts also five skulls came to light. The fossils are indisputably dated 1.8 million years old, and they made from the first release of some sensation in the scientific world.

simply did not fit into the traditional schemes, for the Dmanisi people have characteristics that make them escape the usual categorization. They were small (1.5 meters), had small brains, but a physique, like that of anatomically modern humans allowed long marches, but this is not appropriate primitive arms and hands.

short, they look like a mixture of Homo habilis, Homo ergaster and Homo erectus from. This “human mosaic” presented stone tools and took care of her already obvious to toothless relatives (cf. Toothless in ancient times).

georgius or Homo erectus

The puzzle of morphological characters could not be put together so that the clear attribution to a kind of hominins would have been possible. So Georgian paleontologist suggested first, that the Dmanisi people in a new way called Homo georgius and classify it used to be regarded as the Homo habilis close. What the rest of the professional world but not convinced, the name did not prevail.


now represents an international group of researchers led by David Lordkipanidze from the Georgian National Museum in Tbilisi in the current issue of Science magazine on a new breakthrough: the fifth found, surprisingly intact skull of a Dmanisi people (from A Complete Skull Dmanisi, Georgia, and the Evolutionary Biology of Early Homo). The beautiful piece even adorns the title of the journal.

Portrait of Dmanisi skull No. 5, in profile. Image: Guram Bumbiashvili, National Museum of Georgia

The excavation team found close to each other skull and other bone-Dmanisi of five people who died around the same time. Three men, a young woman and a young ambiguous gender.

five skull probably belonged to the start of the ice age, 1.85 million years ago, an adult male Its cranial capacity is 546 cubic centimeters very small, drawn face long, strong ridges above the eyes resplendent, he had a protruding jaw and very large teeth.

has never been recovered from the earth such an age, so well-preserved skull. It combines the typical morphological features of the seemingly contradictory Dmanisi people in the most pronounced form. Already, he is referred to by colleagues as “fossils icon”.

But he will also trigger violent debates, because Skull 5, together with the other four at the same site excavated skulls, represents the prevailing view of the classification of human fossils in different ways according to the characteristics that they combine to radically question. Explains co-author Christoph Zollikofer, an anthropologist at the University of Zurich:

brain and facial skull of the Dmanisi specimen Had been found as individual parts, they were assigned with high probability two different ways. In the Dmanisi finds it are, first, the population of a single fossil human species. Second, the five Dmanisi individuals actually differ greatly from one another, but no more than any five people, or any five chimpanzees from a modern population.

The research group led by David Lordkipanidze suggests that the previously established subdivisions of simultaneously living two million years ago “Homo habilis”, “Homo habilis”, “Homo ergaster”, etc. and abandon all as “Homo erectus “to designate (see our relationship – a story that becomes more complicated, PDF), because individual differences, the representatives of a variety of different kind, then had been as big as it is today


departure from Africa

The previous species assignments have evolved from a variety of discoveries in Africa, and they are discussed to today is that in the professional world. Christoph Zollikofer explains: “It is mostly fragmentary individual finds that are scattered over large geographical distances, and also come from a period of at least 500,000 years, thus ultimately is not clear whether it is diversity among the African fossils or. to diversity within a species’

The Dmanisi discoveries offer a unique opportunity to analyze very different individuals from the era of Eizeit-onset, who lived in the same place and at the same time. And not only is it highly unlikely that representatives of different types of early humans 1.8 million years ago there met and lived together – they also combine in the features which individually had led to the classification of the different types

It sounds very likely that Homo erectus , two million years ago when he was on his way already in Africa at least as many individual differences exhibited in Georgia later . However, his brain was probably at least on average significantly smaller than assumed up to now. The paleoanthropologists had assumed that he already contributed to his departure from Africa and a brain of about 1,000 cubic centimeters inside his skull.

Aerial view of Dmanisi Archaeological Museum in the context of the medieval city, Photo: Fernando Javier Urquijo

The research group is clear that they have thrown a bomb expert and it is expected that soon violent reactions will follow. Not least because many experts in their self-introduced into the world trade names and classifications are reluctant to abandon. Co-author Marcia Ponce de Leon brings the problem to the point:

Currently there are just so many subdivisions in species as there are scientists who deal with this problem.

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