With the emergence of the genus Homo, we evolved from the stage of ape-man to that of humans. But do not think that we passed from one species to another and the final result is Homo sapiens. The genus Homo produced various species, of which only Homo sapiens survived till today. At a given moment, there were more than one species of Homo on the planet, till very recently, with the total extinction of the Neanderthals.
These are the fossil forms of Homo:

1. Homo rudolfensis: its description is based on a 1.9 million-year-old skull, found near Lake Rudolf (now Turkana) in Kenya. A 2007 research found a 526 cc brain capacity and this species could have resembled more an ape than a human.

2. Homo habilis ("handy man", "skillful person") lived 2.5 to 1.8 million years ago.
It can be the first species of the Homo genus to have appeared. Homo habilis had longer arms compared to modern humans, but a reduced protusion in the face and smaller teeth than Australopithecus. Its immediate ancestor could have been Homo rudolfensis. H. habilis remains have been discovered along with primitive stone tools and and this species lived at the beginning of the Paleolithic ("the old stone age").
The lankier and more sophisticated Homo ergaster but also Homo erectus must have evolved from Homo habilis. It had a brain capacity of 590 and 650 cc, 50% larger than australopithecines (in modern humans it is of 1350 to 1450 cc) and did not bypass 1.3 m (4'3") in height.

H. habilis mastered stone tools but it was not such a skilled hunter, as it was a frequent prey for large cats, like Dinofelis (the size of a modern leopard). This species could have used stone tools primarily for cutting meat off of carrion, rather than defense or hunting and coexisted with ape-men like Paranthropus boisei.

H. habilis was still primitive, lacking typical human traits like slim hips for long distances walk, a complex sweating system, while having still a narrow birth canal and arms longer than legs.

3. Homo georgicus was found Georgia in 1999 and 2001 and is an intermediate between Homo habilis and H. erectus. The species was 1.8 million years old.

The skull has a 600cc brain volume. It is the most primitive hominid found outside of Africa. There is a strong sexual dimorphism present in this case, with males being significantly larger than females. H. georgicus was the first human species to settle in Europe, 800,000 years before H. erectus.

4. Homo ergaster ("working man") lived in eastern/southern Africa between 1.9 and 1.4 million years ago.
Many believe it was just a type of Homo erectus. H. ergaster differed from H. erectus by its thinner skull bones and lack of a visible sulcus.

They had low sexual dimorphism; a smaller, right face, a smaller dental arcade and a larger brain (700 and 850cc). It was approximately 1.9m (6ft3) tall.

H. ergaster created stone hand axes and cleavers, was more advanced than previous species and it seems this species used fire, based on charred animal bones linked to its fossils.

5. Homo erectus (Latin: "upright man") was the first human species that migrated out of Africa around 2.0 million years ago, colonizing most of Eurasia till Southeast Asia. 1.8 to 1.0 million years old remains have been found in eastern Africa, Europe (Georgia, Spain), Indonesia, Vietnam and China.

H. erectus has a less tilted forehead (frontal bone) and the teeth smaller than H. habilis.

Homo erectus was very similar to modern humans, but with 75 % of our brain capacity (950 to 1100 cc). H. erectus had an average height of about 1.79 m (5 feet, 10 inches). Males were 20-30% larger than females.

Homo erectus utilized diverse and sophisticated tools compared to H. habilis and together with H. ergaster was probably the first human species that matched the definition of hunter gatherer.

Despite the similarity with modern humans, H. erectus could not produce complex sounds required by modern speech. H. erectus is the first human species that hunted mammoths 1.8 million years ago in northeastern Africa. There is a vivid debate whether H. erectus used fire or not.

6. Homo antecessor lived in Europe, from Spain to Georgia 1.2 million to 700,000 years ago. The average brain volume was 1000cc and this could be the ancestor of H. heidelbergensis.

Homo antecessor was 5.5 to 6 feet (1.65-1.8 m) tall and males reached weights of 200 pounds (91 kilograms).
Homo antecessor could have been right-handed and this is a difference, if we compare them to apes. Some fossils show signs of cannibalism. This species was very similar to H.ergaster.

7. Homo heidelbergensis ("Heidelberg Man") could be the direct ancestor of Homo neanderthalensis in Europe. It could have appeared from Homo antecessor and lived roughly 600,000 to 250,000 years ago in Europe. It was found in Germany, France, England and Greece.

Rhodesian Man, found in Africa, could belong to this species. In this case Homo heidelbergensis evolved to Homo sapiens in Africa and Neanderthal in Europe.

H. antecessor and H. heidelbergensis are probably the descendants of Homo ergaster. H. heidelbergensis had a larger brain-case, up to 1400 cc, more than the 1350 cc average of modern humans.

This human was tall, 1.8 m (6 ft.) on average and more muscled than H. sapiens.

Cut marks encountered on wild deer, elephants, rhinos and horses showed they could kill animals larger than 1,500 lb (700 kg).

H. heidelbergensis could have acquired a primitive form of language. Bone marks signal cannibalism in this species.

8. The Neanderthal (Homo neanderthalensis) inhabited Europe and neighboring areas of western Asia. The early proto-Neanderthal feathers were found in Europe in fossils which were 350,000 years old. 130,000 years ago, fully Neanderthal traits appeared. About 24,000 years ago the last Neanderthals vanished from southern Spain.

Neanderthals were adapted to a cold climate, having large braincase, short but robust builds and large noses. Their brains were larger than ours. Average Neanderthal males were 1.65 m tall (5' 5"), females 1.57 m tall (5'2").
Mitochondrial DNA analysis clearly showed Neanderthals were not a subspecies of H. sapiens. Some fossil evidence points to the fact that the two species could have interbred.

The hyoid, a crucial bone necessary for the articulated language, was virtually identical to ours, so Neanderthals might have spoken.

The outer and middle ear of their ancestors, H. heidelbergensis, points to an auditory sensitivity similar to H. sapiens and very different from chimps. So, they could also distinguish the emitted sounds.

Neanderthals lacked a mental protuberance (the point at the tip of the chin). There is evidence that Neanderthals used a lot of wood. They used spears as thrusting weapons.

Neanderthals buried their dead. In some cases Neanderthal burials included grave goods, like bison and aurochs bones, tools and the pigment ochre. They built complex shelters, controlled fire and skinned animals and could have practiced cannibalism.

A high frequency of healed fractures shows injured individuals were cared for during times of incapacitation. They may have hunted by leaping onto their prey and stabbing or even wrestling it to the ground. In a cave in Slovenia, researchers found a "flute" made of a femur of cave bear (Ursus spaeleus) and used by Neanderthals 40,000 years ago (the oldest found musical instruments belonging to Homo sapiens are "just" 30,000 years old).

The Neanderthals started to be displaced around 45,000 years ago by modern humans (Homo sapiens), but some small populations held on for thousands of years in regional pockets like in Croatia, Spain and Crimean peninsula. The last known population dwelt on a cave system of Gibraltar, 30,000 - 24,000 years ago.

DNA analysis showed that H. sapiens and H. neanderthalensis lineages diverged around 800,000 years ago.

9. Homo floresiensis ("Man of Flores", Hobbit) is a possible species in the genus Homo, extremely small sized and brained, who survived until recently. It is believed to have been contemporaneous with modern humans on the Indonesian island of Flores.

But many say the fossils could belong to a microcephalic modern human, or could be a pygmy subspecies of H. sapiens.
The individuals were 1.09 m (3 ft 6in) tall, smaller than modern pygmies and a brain size of 380 cc, like in chimps.

This species may have survived longer (12,000 years ago) in Flores to become the source of the Ebu Gogo stories told among the local people. The Ebu Gogo are small, hairy, language-poor cave dwellers on the scale of H. floresiensis. Widely believed to be present at the time of the arrival of the first Portuguese ships during the 16th century, these strange creatures were apparently last spotted as recently as the late 19th century.

10. Homo sapiens idaltu ("elderly wise man") is an extinct subspecies of Homo sapiens that lived 160,000 years ago in Africa. It was found in 1997 in Ethiopia. They had a brain capacity of 1450 cm³.

It still had many archaic features not typical of H. sapiens. These are our direct ancestors, evolved from H. ergaster probably through H. rudolfensis. The first race of H. sapiens sapiens, Khoisan (today's Bushmen), emerged 110,000 years ago in Eastern Africa.