Humans are members of the genus Homo click this icon to hear the preceding term pronounced. Modern people are Homo sapiens click this icon to hear the preceding term pronounced. 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 click this icon to hear the preceding term pronounced, is sufficient reason to place us both into the same biological tribe (Hominini click this icon to hear the preceding term pronounced). Both genera are bipedal and habitually upright in posture. Humans have been somewhat more efficient at this mode of locomotion. Like australopithecines click this icon to hear the preceding term pronounced, 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.
The closest distance between the orbits of these two planets is about 24 million miles. But the actual distance between the two is constantly changing because they orbit the sun at different speeds. At the farthest, these two planets are 162 million miles apart.
