Anthropologists have develop a complicated story of the evolution of hominoid species in Africa. There are several different species, although because so little actual fossil evidence has been found, there is an active debate on whether some of these species are really just variations withering a smaller number of species. Some species are especially important. The most important archaic species are Homo habalis, H. ergaster, and H. erectus. These early fossil remains are extremely rare and thus it is difficult to know for sure if they are really different species. Scientists are, however, making important strides in fitting together the relationship of these different species. And constantly refinined dating methods. The Homo species tend to have increased cranial capacity which generally coincides with the increasingly sophisticated tools some times found with the fossils, but mote cpmmonly wihout any accompanyin fossils. . Homo habilis (2.4 to 1.4 million years BP) means 'handy man' or tool maker. It is one of earliest species of the Homo genus and appears to have been the species that began the path that led us to he moon. The name of the species refers to the tool-making abilities and intermediate features between Australopithecus and subsequent Homo species. Habelis was not the first species to make tools. Other species and not just primates made tools. Habelis is the first species to make tools that no one can doubt were manufactured tools. There is a mixture of ape-like and human-like traits, including long arms, a moderately prognathic face, and a increasingly large brain compared to Australopithecus. Habilis demonstrates the importance of tools is the making of modern man. Habilis like all the ape species in the human evolutionary line, lived in Africa. Homo ergaster (1.7 to 1.4 million years BP) begins to look like modern humans. They were generally tall and slender and are believed to have been increasingly hairless. The Ergaster case is complicated. Many believe Ergaster was really Erectus. And the fossil finds are so limited, it is difficult to make any definitive assessment. Ergaster is, however, believed to be the link between Habilis and Erectus. Homo erectus (2.0/1.9 million to 0.2 million years BP) was probably the first hominid to develop a hunter-gatherer society--the life style practiced by humans for most of our history. And there is no doubt about Erectus status. It is unclear, however, to what extent he was a hunter as opposed to a scavenger. Hunting probably did not become primary until the neolithic era and the ability to make really sophisticated tools, especially weapons. Without weapons, hominid species would be very limited as to what they could hunt and kill. Most anthropologists identify H. erectus as the first hominid to look much like modern humans and to develop social relationships more like modern humans than the more ape-like Australopithecus species that preceded it. The human-like appearance meant specifically long legs and short arms. Those long legs meant that Erectus could travel, While traces were found in Africa about 1.8 million years BP, Erectus spread all over the Eurasian land mass. Erectus had a larger brain reflected in more sophisticated tools. He may also have discovered the use of fire. Erectus has veen described as the most successful of all hominid species, surviving for an incredible time span, approching almost 2 million years, Homo sapiens (0.4/0.3 million years BP ) or modern man originated in Africa These people followeed Erectus and also spread throughout the Eurasian land mass (Old World), eventually reaching the New World. characterized by large brains, bipedalism, complex culture, and of course language. It is unclear to what extent other Humanoids species developed language. There must have been vocalizations of course, but at what point vocalizations became language is unclear. One notable characteristic of H. sapiens is a lack of genetic diversity, far less than most other species. It is believed that this reflects a kind of genetic bottle neck in which only a small number of humans survived. Some believe that this genetic bottle neck was caused by the eruption of the Toba mega-volcano and resulting in a mini-ice age about 75.000 years ago.

Simpler Story: Intra-species Diversity

The findings of ancient hominids are very rare and what has been found are incomplete remains. This has led to an alternative theory that many of the findings are the same specis and that the differences are simply the normal variation within species. Findings at Dmanisi in Georgia have lent credence to this theory which is still a minority view. Anthropologists studying hominid remains at Dmanisi speculate that the story of evolution is much simpler with fewer ancestral species than is commonly believed. They see a single, developing lineage. They believe that Homo erectus, H. habilis and others may represent just variations among hominid individuals of the same species. Researchers have found the remains of five individuals who lived in the same area at about the same time some 1.8 million years ago. The location at Dmanisi suggests that they were part of the process of moving out of Africa and into Eurasia. Skull 5 was particularly important as it is 'the world's first completely preserved adult hominid skull'. [Lordkipanidze and Zollikofer] Skull 5 confirms that hominids did not need big brains to begin the migration out of Africa. And the skull had many ape-like features: long face, large teeth, and a small brain case (about one-third that of modern humans). The Dmanisi researhers believe that had the remains thy found been at different locations, anthropologists would have identified different species. This was especially case of skull 5 with a brain case and face that would seem to come from different species. This would mean that the decades-old origin story for our species, which tended to see a single origin location probably in East Africa has serious weaknesses. There have been fossil finds all over Africa, the East, South, Cenntra, and now even the North. The ancient human fossils from a Moroccan cave, Jebel Irhoud, in 2017 startled many. They are believed to be H. sapienes and may be 315,000-year-old bones -- the oldest known H. sapienes adding northwest Africa to the possible origin sites. African-multiregionalism advocates argue that H. sapiens emerged from an ancestral hominid that was widespread throughout Africa, but separated into many isolated populations. Humans thus evolved within these groups, but no further speciation occurred because these groups were not sedentary. They occasionally encounters other groups and occasionally mated with each other. [Young]

Sources

Lordkipanidze, David (Georgian National Mueum) and Christoph Zollikofer (University of Zurich). Science (October 17, 2013).

Young, Ed. "The New Story of Humanity's Origins in Africa," Science (July 11, 2018).