peter jay stein, md, ma
This 54 page synopsis of the evolution
of the Earth, the origin and progression of life, and the
emergence of humans as descendants of the hominin lineage, divides the last 4.57 billion years into progressively overlapping, imagistic, time segments, to outline our place in biological existence.
A Recent Hominin Discovery
adapted from PBS NOVA, Dawn of Humanity, 2015/2016 (youtube), and The New York Times, 9/10/2015
Paleoanthropologists seek to make sense of the evolutionary transition(s) from "ape" to human, i.e., from bipedal, ape-like hominins to our own genus, 'Homo'.
With the discovery and recovery of over 1500 fossilized bones, tentatively believed to be from 1.7-3.0 million years old, excavated from the Rising Star Cave in S. Africa in 2014/2015, a scientific team led by American paleoanthropologist Lee Berger, report the possibilities that this new species, named Homo Naledi, may illustrate rudimentary burial practices, in an early hominin clade, whose brain size is only slightly larger than a chimp (i.e., slightly >400cc).
Rituals, such as burying the dead, indicative of advancing social bonding, are of special significance to the understanding of the emergence and survival of human beings, i.e. modern Homo sapiens.
Early human-like apes, found to have a predominantly vegetarian diet, from microscopic examination of fossil tooth calculi (tarter)*, were more likely victims of predation, rather than murderous, meat-eating aggressors, as first surmised by Raymond Dart, in 1925, having examined the skull of the Taung Child, which he named Australopithecus africanus.
Also clearer among paleoanthropologists, is that earlier, differing hominins possessed varying mosaics of features, some features more advanced, as seen with more human-like lower limbs, posture and bipedalism, while retaining earlier, more primitive forms of cranial size and shape, in the same individual.
Humans, in their cooperative and bonding behavior, have developed the highest degree of relational complexity among terrestrial mammals, features selected by evolution. This suggests that complex, cooperative behavior promoted reproduction and survival in earlier, human-like groups, within the harsh environments of the African landscapes.
Such an historical perspective suggests that "survival of those who collaborate, cooperate, and work together," represents a more precise way of re-conceptualizing "survival of the fittest".
*Silica phytoliths (microscopic remains originating in plant tissues) have been identified on the enamel surface and dental calculus of a sample of teeth selected from well preserved skeletons...[the] study of phytoliths can provide direct information about the vegetable diet of past human populations, and could be applied to the study of human fossils.
from the Am J Phys Anthropol. 1996 Sep;101(1):101-13.