Perhaps, human evolution began nearly 4.5 mln. years ago. It is believed that one of the the most ancient ancestors of humans was Ardipithecus ramidis. At the same time, it was not the ancestor of all ape species. Its fossils were discovered in 1994 and their age was estimated as 4.4 mln. years. Unfortunately, they are very fragmentary and we cannot say much about Ardipithecus. It might have had bipedal locomotion but climbed trees at the same time.

The following species was Australopithecus anamensis, belonging to genus Australopithecines. Family of humans, called Hominidae, is divided into two genera: Australopithecines and Homo. All Homo species, except for Homo sapiens sapiens, have become extinct. Last australopithecines disappeared about 1 mln. years ago. Thus, Homo sapiens sapiens is only human species to exist nowadays (I do not take into account the "Yeti", "Bigfoot", and other mysterious beings that could be last representatives of the extinct species ). Australopithecus anamensis lived about 4.2-3.8 mln. years ago. Its remains show that this species was bipedal. Consequently, it leaves no doubt that anamensis refers to humans. The following species, living slightly later, 3.9-3.0 mln. years ago, is named Australopithecus afarensis. The most famous find of this species was "Lucy", discovered by D. Johanson in 1974. It had more human features, especially in skull structure. Brain size was 400-500 cc. Both Australopithecines anamensis and afarensis are characterized by strong sexual dimorphism. It means that males were much taller than females. Height of males was about 150-160 cm, and that of females 100-120 cm only. One more species was Australopithecus africanus. It existed later than Australopithecus afarensis, 3-2.1 mln. years ago, and its features were similar to those of afarensis.

All three species, anamemsis, afarensis, and africanus refer to so-called gracile australopithecines. In general australopithecines can be divided into two groups: gracile (or early) and robust (or later). The groups have two main differences. First one is that gracile australopithecines were omnivorous, whereas the diet of robust australopithecines was only vegetable. Second one is that robust australopithecines were more heavily built. It especially concerns their head. It had a special crest on the top of the skull. That crest probably prevented from developing of the brain, while the advanced features of gracile australopithecines, such as large cranial capacity, bipedal walking, and adaptation to mixed diet, continued to evolve. Perhaps, gracile australopithecines just gave rise to Homo.

Three main species of robust australopithecines are known. Australopithecus aethiopicus is believed to be the oldest among them. It lived between 2.6 and 2.3 mln. years ago. Australopithecus boisei existed later, 2.1 - 1.1 mln. years ago. However, some scientists put them into one group, Australopithecus boisei, because both the species are very similar. Australopithecus boisei was the most heavily built among the other robust australopithecines. It had relatively short legs, a big crest on the skull, and massive molars. Australopithecus robustus lived about 2.0 -1.5 mln. years ago. Some features of this species resemble those of Australopithecus africanus, so some paleoanthropologists believe that robustus originated from africanus. Other scientists consider robustus as the direct descendant of Australopithecus boisei. Anyway, all the robust australopithecines disappeared from the face of Earth about 1 mln. years ago.

Possibly, the oldest Homo species was Homo habilis, "handy man", living between 2.4 and 1.5 mln. years ago. It was called so because some stone tools were discovered near its remains. Most likely, Australopithecines could not make tools systematically, so Homo habilis can be considered as the first "true man". However, some scientists believe that the first species to refer to Homo was Homo rudolfensis, whose brain (600 - 800 cc) was much bigger than that of australopithecines (400 - 500 cc). Later Homo species, Homo erectus, had even larger brain, varying between 750-1200 cc. This species existed 1.8 mln. - 300,000 years ago. It is noteworthy for the fact that it was the first human species to migrate to other continents. It occurred about 1.8-1.5 mln. years ago. As a result, somewhat different subspecies of Homo erectus appeared on different continents. For example, Sinanthropus (or Pithecanthropus) lived in South-Eastern Asia, Homo ergaster - in Eastern Africa, Homo heidelbergensis - in Europe.

The latter species, Homo heidelbergensis is often considered to be a separate species from erectus, and called Homo sapiens archaic, due to its close resemblance to modern Homo sapiens. This species appeared about 700,000 - 500,000 years ago. Homo sapiens archaic gave rise to the next sapiens species, Homo sapiens neanderthalensis, living between 300,000 and 30,000 years ago. Neanderthals were not tall, but were very strong. Their bodies were adapted to cold climate. Not only did Neanderthals have different appearance from that of first Homo species, but they also had quite different way of thinking. Their stone tools were much more perfect, than those of Homo erectus. Neanderthals were intelligent, they had rudimentary religion and buried their dead. However, Neanderthals became extinct about 27,000 years ago, left the planet to a new species, Homo sapiens sapiens, first appearing nearly 120,000 years ago. Human beings, belonging to this species, are none other than we, modern people. Unlike the other hominid species, we have not become extinct, but we have managed to create the weapon, that can wipe the humankind off the face of the Earth...