Instead, human evolution has been throughout its long history a matter of experimentation, with new species being constantly spawned and thrown into the ecological arena to compete and, more often than not, become extinct.
Viewed this way, is simply the last surviving twig on a vast and intricately branching bush, rather than the sole occupant of a summit that has been laboriously climbed and, by extension, somehow earned.
These fossils, along with the slightly older trails of footprints found at Laetoli, Tanzania, prove that early hominins were upright bipeds when on the ground.
However, they also retained many reminders of their tree-dwelling ancestry, especially their rather long arms, short legs, narrow shoulders, and long grasping extremities.
Announced in 2002, this specimen is dated to the period between 7 and 6 mya.
The molecular clock concept is based on an assumed regularity in the accumulation of tiny changes in the genetic codes of humans and other organisms.
Use of this concept, together with a reanalysis of the fossil record, moved the estimated time of the evolutionary split between apes and human ancestors forward to as recently as about 5 mya.
No consensus has developed on exactly where this find fits into the human family tree (or, more appropriately, “family bush”), but, even if it is a hominin, it is highly unlikely to be a direct ancestor of , then, emphasizes an evolutionary pattern that seems to have been a characteristic of the tribe Hominini from the very start—a pattern that aligns it with what is observed in most other evolutionarily successful groups of mammals.
Human evolution, it appears, has consistently been a process of trial and error.
Fossils found since the early 1990s have begun to hint at just how complex the hominin bush was in the three million years or so following the time of , both known from South and East African sites.