They find, first, fossilized jaw Homo habilis 2.8 million years ago; the other, more recent fossils seem to combine the H. habilis with Australopithecus .
The fossil jaw LD 350-1, found by graduate student Chalachew Seyoum. Photo: Courtesy Science / Kaye Reed
For a long time scientists have tried to define when and how the genus Homo arose (to which we belong modern sapiens and could be translated as “human”); Today two published simultaneously by the journals Science and Nature works give an idea of time and space in which apparently inhabited the oldest known Homo so far, with 2.8 million years ago.
“A 50 years of the recognition of the species Homo habilis as the oldest representative of our genus, the origin of Homo remains nebulous. This uncertainty comes in part from the very limited fossil record does 2-3000000 years (ma) (…). Some species of this period, such as Australopithecus africanus (2.8 – 2.3 m) and less famous A. garhi (~ 2.5 m) and A. aethiopicus (~ 2.7 – 2.3 m), seem to be too different in their skulls and teeth You represent a probable ancestor of Homo species was in Africa some 2 m (H. habilis and H. rudolfensis). “
Read from the Science article signed by Brian Villamoare as lead author, the finding of a jaw of H. habilis 2.8 million years old found in Afar, Ethiopia is reported.
Moreover, jaw and skull fragments found at Olduvai, Tanzania, another specimen H. habilis, show a mixture with features of Australopithecus, suggesting the principal authors of the Nature paper (Fred Spoor and Phillip Gunz) that both genders diverged evolutionarily well before 2.3 million years, as confirmed by the finding of Villamoare .
The first human family
The analysis by Villmoare, University of Nevada, et al, explains that “the specialness of this jaw is not only the date, much older than any known Homo so far, but has a number of unique features, from the height of the mandible to the shape of the teeth, which makes a clear transition between Australopithecus and Homo.
“On one side are fine molars, premolars and a jaw symmetric uniform proportions that distinguishes early Homo species lineage, however, primitive features and a sloping chin guard closest thing also seen with Old Lucy “(the most complete skeleton of Australopithecus afarensis is discovered in 1974).
” Despite intensive search, fossil Homo lineage over 2 million years are very rare, so you can take a look at the earliest stage of the evolution of our lineage is particularly exciting, “said researcher at the international press conference.
The fossil found in 2013 by a international team of geoscientists and anthropologists in the research area called Ledi-Geraru even suggests many unknowns, so that authors do not dare to propose exactly what species and now I have called individual LD 350-1.
The geologist Erin DiMaggio, University of Pennsylvania, said in teleconference that “the hominid fossil record of chronologies between 2.5 and 3 million years is still very poor,” however, this finding is reliable “We have used various dating methods such as radiometric analysis of volcanic ash and measuring isotopes of argon, it appears that is between 2.75 and 2.8 million years,” thus determined that the eruption that originated the sample occurred in that period.
A combination of Homo and Australopithecus?
In the parallel research published in Nature, a team at the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University London, presented a new reconstruction of a jaw belonging to an individual of Homo habilis 1.8 million years found in Olduvai, Tanzania (called OH 7).
Here reconstruction presents an unexpectedly early portrait This Homo, more like Australopithecus that Homo erectus and H. sapiens, indicating that the species may have appeared before the face of the Earth (up to 2.3 million years).
Surprise it seems to coincide well with the fossil jaw LD 350-1; In addition, the analysis also indicates that early Homo were diverse and distinguished more by variations in facial features that differences in brain size.
“A sophisticated statistical analysis reveals differences in the way jaw between these early human species, sometimes the differences are as large as those between humans and chimpanzees, “says Philipp Gunz, in a statement of Max Planck and one of the lead authors of the study.
“Before -continued Gunz-, differences in brain size used to be considered important to characterize early Homo species, but these analyzes show that the three species can not be distinguished by the size of the brain but by their appearance facial “.
But more importantly, traces of 2.3 million years ago, which until this week were thought to be the oldest Homo habilis early and Tanzania, 1.8 million years ago, seem represent the lineage that separated well before 2.3 million years, “with a common ancestor that had remained hidden until this week,” reads the statement of the Max Plank.
The environmental context gave rise gender?
Moreover, researchers found the jaw 2.8 million years ago also located the remains of antelopes, prehistoric elephants, a type of hippo, crocodiles and fish, all with 2.84 and 2.54 million years.
These fossils suggest that at that time the area was a place open grassland and scrub surrounded by trees along rivers or wetlands, the landscape seems similar to the African places like the plains of the Serengeti or the Kalahari.
Responding to the theory of some scientists believe that global climate change that occurred at that time led to aridity in Africa and prompted many evolutionary changes . mammals, also caused the emergence and extinction of species and perhaps also the birth of Homo
Kaye E. Reed, professor at the Institute of Human Origins at Arizona State University, said: “You can see signal aridity 2.8 million years ago in the fauna of Ledi-Geraru, but it is too early to say that this means that climate change is responsible for the origin of Homo. We need a larger sample of fossils of hominids and will certainly continue looking into this area. “
nelly.toche@eleconomista.mx
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