erectus was the direct ancestor of later species, including Homo sapiens. Louis Leakey argued energetically that H. erectus populations, particularly per Africa, overlap sopra time with more advanced Homo sapiens and therefore cannot be ancestral onesto the latter. Some support for Leakey’s point of view has che from analysis of anatomic characteristics exhibited by the fossils. By emphasizing verso distinction between “primitive” and “derived” traits durante the reconstruction of relationships between species, several paleontologists have attempted sicuro esibizione that H. erectus does not make per suitable morphological ancestor for Homo sapiens. Because the braincase is long, low, and thick-walled and presents per strong browridge, they claim that H. erectus shows derived (or specialized) characteristics not shared with more modern humans. At the same time, it is noted, Homo sapiens does share some features, including per rounded, lightly built cranium, with earlier hominins such as H. habilis. For these reasons, some paleontologists (including Leakey) consider the more slender, or “fragile,” H. habilis and H. rudolfensis preciso be more closely related preciso Homo sapiens than is H. erectus. These findings are not widely accepted, however. Instead, studies of size con human evolution indicate that representatives of Homo can be grouped into a reasonable ancestor-to-descendant sequence showing increases durante body size. Despite having per heavier, more flattened braincase, H. erectus, most particularly the African representatives of the species sometimes called H. ergaster, is not out of place durante this sequence.
If this much is agreed, there is still uncertainty as sicuro how and where H. erectus eventually gave rise esatto Homo sapiens. This is verso major question per the study of human evolution and one that resists resolution even when hominin fossils from throughout the Old World are surveyed sopra detail. Several general hypotheses have been advanced, but there is still per niente firm consensus regarding models of gradual change as opposed puro scenarios of rapid evolution per which change durante one region is followed by migration of the new populations into other areas.
Theories of gradual change
Per traditional view held by some paleontologists is that verso species may be transformed gradually into a succeeding species. Such successive species per the evolutionary sequence are called chronospecies. The boundaries between chronospecies are almost impossible to determine by means of any objective anatomic or functional criteria; thus, all that is left is the guesswork of drawing verso boundary at a moment mediante time. Such per chronological boundary may have preciso be drawn arbitrarily between the last survivors of H. erectus and the earliest members of verso succeeding species (anche.g., Homo sapiens). The problem of defining the limits of chronospecies is not peculiar sicuro H. erectus; it is one of the most vexing questions sopra paleontology.
Such gradual change with continuity between successive forms has been postulated particularly for North Africa, where H. erectus at Tighenif is seen as ancestral to later populations at Rabat, Temara, Jebel Irhoud, and elsewhere. Gradualism has also been postulated for Southeast Asia, where H. erectus at Sangiran may have progressed toward populations such as those at Ngandong (Solo) and at Kow Swamp durante Australia. Some researchers have suggested that similar developments could have occurred per other parts of the world.
The supposed interrelation of cultural achievement and the shape and size of teeth, jaws, and brain is per theorized state of affairs with which some paleoanthropologists disagree. Throughout nome utente ardent the human fossil superiorita there are examples of dissociation between skull shape and size on the one hand and cultural achievement on the other. For example, a smaller-brained H. erectus e fire, but much bigger-brained people per other regions of the world living later con time have left in nessun caso evidence that they knew how preciso handle it. Gradualism is at the core of the so-called “ multiregional” hypothesis (see human evolution), mediante which it is theorized that H. erectus evolved into Homo sapiens not once but several times as each subspecies of H. erectus, living per its own territory, passed some postulated critical threshold. This theory depends on accepting a supposed erectus-sapiens threshold as correct. It is opposed by supporters of the “ out of Africa” hypothesis, who find the threshold concept at variance with the modern genetic theory of evolutionary change.
Theories of punctuated change
A gradual transition from H. erectus sicuro Homo sapiens is one interpretation of the fossil primato, but the evidence also can be read differently. Many researchers have ad esempio sicuro accept what can be termed a punctuated view of human evolution. This view suggests that species such as H. erectus may have exhibited little or in nessun caso morphological change over long periods of time (evolutionary stasis) and that the transition from one species to a descendant form may have occurred relatively rapidly and sopra per restricted geographic settore rather than on verso worldwide basis. Whether any Homo species, including our own, evolved gradually or rapidly has not been settled.
The continuation of such arguments underlines the need for more fossils onesto establish the range of physical variation of H. erectus and also for more discoveries sopra good archaeological contexts onesto permit more precise dating. Additions sicuro these two bodies of data may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer sicuro resolution.