Archaeologica.org

Scientists long have focused on how climate and vegetation allowed human ancestors to evolve in Africa. Now, University of Utah geologists are calling renewed attention to the idea that ground movements formed mountains and valleys, creating environments that favored the emergence of humanity.

“Tectonics [movement of Earth’s crust] was ultimately responsible for the evolution of humankind,” Royhan and Nahid Gani of the university’s Energy and Geoscience Institute write in the January, 2008, issue of Geotimes, published by the American Geological Institute.

They argue that the accelerated uplift of mountains and highlands stretching from Ethiopia to South Africa blocked much ocean moisture, converting lush tropical forests into an arid patchwork of woodlands and savannah grasslands that gradually favored human ancestors who came down from the trees and started walking on two feet – an energy-efficient way to search larger areas for food in an arid environment.

an energy-efficient way to search larger areas for food in an arid environment.

Digit wrote:Pass! What's concealed ovalation?

At least one recent study has argued that men are more likely to initiate sex with fertile women[

CHICAGO (AFP) - French fossil hunters have pinned down the age of Toumai, which they contend is the remains of the earliest human ever found, at between 6.8 and 7.2 million years old.

The fossil was discovered in the Chadian desert in 2001 and an intense debate ensued over whether the nearly complete cranium, pieces of jawbone and teeth belonged to one of our earliest ancestors.

Critics said that Toumai's cranium was too squashed to be that of a hominid -- it did not have the brain capacity that gives humans primacy -- and its small size indicated a creature of no more than 120 centimetres (four feet) in height, about the size of a walking chimp.

In short, they said, Toumai had no right to be baptised with French researcher Michel Brunet's hominid honorific of Sahelanthropus tchadensis -- he was simply a vulgar ape.

Toumai's supporters used 3D computer reconstructions to show that the structure of the cranium had clear differences from those of gorillas and chimps and indicates that Toumai was able to walk upright on two feet, something our primate cousins cannot do with ease.

If Toumai is truly an early human, that means that the evolutionary split between apes and humans occurred far earlier than previously thought.

Beagle wrote:This pushes the curtain back quite a bit.

Approximately 100 species of apes lived during this time. They occupied much of the Old World and ranged in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominoid clade, but molecular evidence indicates this ape lived from between 15 to 12 million years ago.

CHICAGO (AFP) - French fossil hunters have pinned down the age of Toumai, which they contend is the remains of the earliest human ever found, at between 6.8 and 7.2 million years old.

Newswise — 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.

An analysis of six-million-year-old bones from an early human ancestor that lived in what is now Kenya suggests that the species was the earliest known hominin to walk, a new study says.

"This provides really solid evidence that these fossils actually belong to an upright-walking early human ancestor," said study lead author Brian Richmond, a biological anthropologist at George Washington University in Washington, D.C.

Orrorin tugenensis, known by only a handful of bones, has generated controversy since its discovery in the hills of northwest Kenya in 2000.

The species existed during a critical period in the human evolutionary timeline. The genetic differences between human and chimpanzee lineages point to divergence from a common ancestor that lived somewhere between five and eight million years ago.

A University of Arkansas professor and his colleagues used a combination of microscopy and fractal analysis to examine marks on the teeth of members of an ancient human ancestor species and found that what it actually ate does not correspond with the size and shape of its teeth. This finding suggests that structure alone is not enough to predict dietary preferences and that evolutionary adaptation for eating may have been based on scarcity rather than on an animal's regular diet.

"These findings totally run counter to what people have been saying for the last half a century," said Peter Ungar, professor of anthropology in the J. William Fulbright College of Arts and Sciences. "We have to sit back and re-evaluate what we once thought