human evolution
...ore possible hominines. Because of variation in their teeth, jaws, and brain size, they modify enough among themselves to be divided into five species: Australopithecus anamensis, A. afarensis, A. africanus, A. robustus, and A. boisei. Genus Homo is also divided in five different spices: Homo erectus, H. habilis, H. sapiens, and H. sapiens sapiens. According to evolution theory, first human evolved from australopithecus afarensis. The recently popular sequence is Australopithecus afarensis to Homo habilis to Homo erectus to Homo sapiens to Homo sapien sapien or Modern human All primates have the following characteristics. Humans, apes, and other primates have grasping hands with opposable thumbs. Opposable thumbs can touch the tip of each finger, enabling primates to easily manipulate objects and use a variety of tools. Unlike human hands, the hands of gorillas and other apes are adapted for both walking and grasping. Presence of Finger nails, On the forward facing skull the eye sockets are both looking forward giving this type of animal the ability to judge depth. At a side view of a skull, size of the cranium tells us how big the brain was. Primates have very large forebrains. A similarity in the length of the gestation period is found. Fetal development in both humans and apes is between 250 and 280 days. The two species reach sexual maturity between the ages of 8 and 15 years due to the secreting of hormones. Many people do not like to consider Humans as primates. It is the physical differences that make human beings unique. The following list will describe some of the major differences. Human brain size averages 1,350 cm3, whereas a chimpanzees’ is only about 350 cm3. Human nose and mouth are almost straight down from our eyes, whereas that of other primates jut out. Humans have Small Jaw and Teeth: Even though Human beings have the same number of teeth as chimpanzees, their teeth are much larger. Foramen Magnum, the opening at the base of the Cranium that the spinal cord comes out of, is directly underneath the skull, which enables humans to walk upright. The foreman magnum of other primates is moved further towards the back of the skull. Human spine is curved which enables them to walk upright. Other primates have straight spines. There is a ratio between the sizes of the arms compared to the legs. A gorilla’s arms are much longer than his legs, while human arms are shorter than our legs. Human are the only primate who has his big toes in line with the other toes. The other primates have opposable big toes. Two-leg walking seems to be one of the earliest of the major hominine characteristics. In the course of human evolution the size of the brain has been more than tripled. The increase in brain size may be related to changes in hominine behavior. Genetic evidence, after comparing our DNA with that of apes has provided us with new information about our relation with apes. According to these genetic evidences, Asian apes, gibbons and orangutans are not closely related to us or to the African apes. But human DNA is surprisingly almost identical with the DNA of chimps and gorillas. Both chimps, and gorillas hav...