Christophe a écrit :dedeleco a décidé de pourrir tout le forum ou bien?
J'avais lu qu'on ne pouvait pas détecter le virus du sida directement: les photos de dédéleco c'est quoi alors?
The research is the first thorough quantitative analysis of the Orrorin tugenensis fossil – a fragmentary piece of femur – which was discovered in Kenya in 2000 by a French research team
A shape comparison of the most complete fossil femur (thigh bone) of one of the earliest known pre-humans, or hominins, with the femora of living apes, modern humans and other fossils, indicates the earliest form of bipedalism occurred at least six million years ago and persisted for at least four million years. William Jungers, Ph.D., of Stony Brook University, and Brian Richmond, Ph.D., of George Washington University, say their finding indicates that the fossil belongs to very early human ancestors, and that upright walking is one of the first human characteristics to appear in our lineage, right after the split between human and chimpanzee lineages. Their findings are published in the March 21 issue of the journal Science.
GWU’s Center for the Advanced Study of Hominid Paleobiology, completed a multivariate analysis of the proximal femora shape of a young adult O. tugenensis that enabled them to pinpoint the pattern of bipedal gait for this controversial hominin. Their analysis included a large and diverse sample of apes, other early hominins, including Australopithecus, and modern humans of all body sizes.
“This research solidifies the evidence that the human lineage split off as far back as six million years ago, that we share ancestry with Orrorin, and that our ancestors were walking upright at the time,” says Dr. Richmond. “These answers were not clear before this analysis.”
“Our study confirms that as early as six million years ago, basal hominins in Africa were already similar to later australopithecines in their anatomy and inferred locomotor biomechanics,” adds Dr. Jungers. “At the same time, by way of the analysis, we see no special phylogenetic connection between Orrorin and our own genus, Homo.”
In “Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism,” the authors articulate that the analysis and morphological comparisons among femora from the fossils showed that O. tugenensis is distinct from those of modern humans and the great apes in having a long, anteroposteriorly narrow neck and wide proximal shaft. Early Homo femora have larger heads and broader necks compared to early hominins. In addition to these features, modern human femora have short necks and mediolaterally narrow shafts.
The challenge ahead, explains Dr. Jungers, is “to identify what precipitated the change from this ancient and successful adaptation of upright walking, and climbing, to our own obligate form of bipedalism.”
Altogether, the evidence leans against the idea that our own bipedalism evolved from a knuckle-walking ancestor, the pair wrote. "Instead, our data support the opposite notion, that features of the hand and wrist found in the human fossil record that have traditionally been treated as indicators of knuckle-walking behavior in general are in fact evidence of arboreality."
In other words, a long-ago ancestor species that spent its time in the trees moved to the ground and began walking upright.
There are no fossils from the time of this transition, which likely occurred about seven million years ago, Kivell and Schmitt said. But none of the later fossils considered to be on the direct human line were knuckle-walkers.
dedeleco a écrit :Le virus du SIDA a été découvert, identifié et existe et est appelé VIH depuis les années 1980 !!
J'ai écrit " rares fossiles" !!!
janic ne voit que ses à priori négatifs, dans sa négation habituelle, et pas les éléments de preuves apportés !!!
et janic devrait lire positivement et pas négativement cette évidence oubliée, d'évolution, qui nous a mis sur nos pieds, pour trimballer notre nourriture, pour aller pécher fort loin et prendre des réserves d'eau et après suer au soleil :
dedeleco a écrit :Pur vocabulaire, typiquement humain (pour accepter ou se cacher la réalité),
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