14. compare how do the skull and brain sizesof modern humans compare to the skulls ofearly primates, such as australopithecines?

Humans are members of the genus Homo .  Modern people are Homo sapiens .  However, we are not the only species of humans who have ever lived.  There were earlier species of our genus that are now extinct.  In the past, it was incorrectly assumed that human evolution was a relatively straightforward sequence of one species evolving into another.  We now understand that there were times when several species of humans and even other hominins were alive.  This complex pattern of evolution emerging from the fossil record has been aptly described as a luxuriantly branching bush on which all but one twig has died off.  Modern humans are that last living twig.  Complicating this evolutionary history even more is the realization that our ancestors very likely mated successfully with members of other closely related species from time to time.  As a consequence, our inherited gene pool was enriched by added genetic diversity.  This sort of genetic mixing has recently been documented for Neandertals and early modern Homo sapiens living 40-60,000 years ago.  It is also likely that there were genetic bottle necking events that periodically reduced our diversity.  That largely accounts for the fact that despite our huge human population today, we are remarkably similar genetically compared to other primate species.  It also explains why we are now the only surviving hominin species.

The striking similarities in appearance between the human genus Homo and our ancestors, the genus Australopithecus , is sufficient reason to place us both into the same biological tribe (Hominini ).  Both genera are bipedal and habitually upright in posture.  Humans have been somewhat more efficient at this mode of locomotion.  Like australopithecines , early humans were light in frame and relatively short.  They were only about 3 ft. 4 in. to 4 ft. 5 in. tall (100-235 cm) and weighed around 70 pounds (32 kg)  The evolution of larger bodies occurred later in human evolution.  The differences between australopithecines and early humans are most noticeable in the head.  Humans developed significantly larger brains and relatively smaller faces with progressively smaller teeth and jaws.  In addition, humans became ever more proficient in developing cultural technologies to aid in their survival, while the australopithecines did not.

  Late australopithecine  Early transitional human

The immediate ancestors of early humans were most likely late australopithecines.  At present, the leading contender for that ancestral species is Australopithecus garhi  or possibly Australopithecus africanus. 

There may have been one or possibly two species of the first humans living in East Africa--Homo rudolfensis  and Homo habilis .  The few rudolfensis fossils that have been found are somewhat earlier, dating about 2.4-1.6 million years ago, while the more common habilis remains are around 1.9-1.4 million years old.  Rudolfensis apparently was a bit taller and relatively larger brained on average.  However, many paleoanthropologists consider the differences to be too slight to warrant a separate species designation.  Some have suggested that rudolfensis were males and habilis were females.  As a result, they classify them both as a single species--Homo habilis.  That is the approach taken in this tutorial.

The answer is metamorphic.

Answer1800 million years ago;