Richard Leakey: Human

“[Fred] Spoor's observations are truly startling, In all species of the genus Homo, the inner ear structure is indistinguishable from that of modern humans. Similarly, in all species of Australopithecus, the semicircular canals look like those of apes. Does this mean that the australopithecines moved about as apes do—that is, quadrupedally? The structure of the pelvis and lower limbs speaks against this conclusion. So does a remarkable discovery my mother made in 1976: a trail of very humanlike footprints made in a layer of volcanic ash some 3.75 million years ago.”

“Natural selection operates according to immediate circumstances and not toward a long-term goal. Homo sapiens did eventually evolve as a descendent of the first humans, but there was nothing inevitable about it.”

“When our ancestors discovered the trick of consistently producing sharp stone flakes, it constituted a major breakthrough in human prehistory. …The modest flake… is a highly effective implement for cutting through all but the toughest of hides… the humans who made and used these simple stone flakes thereby availed themselves of a new energy source—animal protein.”

“Dots are just one example of an element in Lascaux art, and in all cave art… This is a profusion of nonrepresentational, geometric patterns. In addition to dots, there are grids and chevrons, curves and zigzags, and more. …The coincidence of these geometric motifs with representational images is one of the most puzzling aspects of Upper Paleolithic art. …images, six different kinds in all, are shimmering, incandescent, mercurial—and powerful. Called entoptic images—which means "within vision"—these phenomena are products of the basic neural architecture of the human brain.”

“Three revolutions mark the history of life on earth. The first was the origin of life itself… The second… was the origin of multicellular organisms… The origin of human consciousness… was the third… Life became aware of itself, and began to transform the world of nature to its own ends.”

“The neurobiologist Harry Jerison has made a long study of the trajectory of brain evolution since the advent of life on dry land. …the origin of new faunal groups is usually accompanied by a jump in the relative size of the brain, known as encephalization. …the first archaic mammals… were equipped with brains four to five times bigger than the average reptilian brain… primates are twice as encephalized as the average mammal. Within primates, the apes… are some twice the average size. And humans are three times as encephalized as the average ape.”

“People who pass from stage two hallucination to stage three often experience a sensation of a vortex or rotating tunnel around them, and soon have hallucinations filled with iconic images, not just signs. …It is here that "monsters" appear, part human, part beast, known as therianthropes.”

“Ever since Darwin tied knots between human beings and the rest of the animal world, many people have frantically attempted to untie them again, declaring that even though our roots are in the animal world we have left them so far behind as to make any comparisons utterly meaningless. To some extent this is true, because the quality that makes us unique in the biological kingdom is the enormous capacity to learn.”

“Rather than living as aggregations of families in nomadic bands, as modern hunter-gatherers do, the first humans probably lived like savanna baboons.”

“We are justified in calling all species of bipedal ape "human."… the adaptation of bipedalism was so loaded with evolutionary potential—freeing the upper limbs to be free to become manipulative implements one day—that its importance should be recognized in our nomenclature. These humans were not like us, but without the bipedal adaptation they couldn't have become us.”