erectus was the direct ancestor of later species, including Homo sapiens. Louis Leakey argued energetically that H. erectus populations, particularly in Africa, overlap in time with more advanced Homo sapiens and therefore cannot be ancestral sicuro the latter. Some support for Leakey’s point of view has che tipo di from analysis of anatomic characteristics exhibited by the fossils. By emphasizing per distinction between “primitive” and “derived” traits con the reconstruction of relationships between species, several paleontologists have attempted to show that H. erectus does not make verso suitable morphological ancestor for Homo sapiens. Because the braincase is long, low, and thick-walled and presents a 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 a rounded, lightly built cranium, with earlier hominins such as H. habilis. For these reasons, some paleontologists (including Leakey) consider the more slender, or “esile,” H. habilis and H. rudolfensis preciso be more closely related to Homo sapiens than is H. erectus. These findings are not widely accepted, however. Instead, studies of size per human evolution indicate that representatives of Homo can be grouped into verso reasonable ancestor-to-descendant codice promozionale fdating sequence showing increases mediante body size. Despite having verso heavier, more flattened braincase, H. erectus, most particularly the African representatives of the species sometimes called H. ergaster, is not out of place per this sequence.
If this much is agreed, there is still uncertainty as puro how and where H. erectus eventually gave rise esatto Homo sapiens. This is a major question con the study of human evolution and one that resists resolution even when hominin fossils from throughout the Old World are surveyed durante detail. Several general hypotheses have been advanced, but there is still niente affatto firm consensus regarding models of gradual change as opposed puro scenarios of rapid evolution sopra which change con one region is followed by migration of the new populations into other areas.
Theories of gradual change
Verso traditional view held by some paleontologists is that verso species may be transformed gradually into verso succeeding species. Such successive species sopra the evolutionary sequence are called chronospecies. The boundaries between chronospecies are almost impossible puro determine by means of any objective anatomic or functional criteria; thus, all that is left is the guesswork of drawing a boundary at a moment sopra time. Such per chronological boundary may have sicuro 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 onesto H. erectus; it is one of the most vexing questions mediante 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 puro later populations at Rabat, Temara, Jebel Irhoud, and elsewhere. Gradualism has also been postulated for Southeast Levante, where H. erectus at Sangiran may have progressed toward populations such as those at Ngandong (Solo) and at Kow Swamp sopra Australia. Some researchers have suggested that similar developments could have occurred sopra other parts of the world.
The supposed interrelation of cultural achievement and the shape and size of teeth, jaws, and brain is verso theorized state of affairs with which some paleoanthropologists disagree. Throughout the human fossil record there are examples of dissociation between skull shape and size on the one hand and cultural achievement on the other. For example, per smaller-brained H. erectus di nuovo fire, but much bigger-brained people in other regions of the world living later durante time have left per niente evidence that they knew how onesto handle it. Gradualism is at the core of the so-called “ multiregional” hypothesis (see human evolution), durante which it is theorized that H. erectus evolved into Homo sapiens not once but several times as each subspecies of H. erectus, living durante its own territory, passed some postulated critical threshold. This theory depends on accepting per 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
Verso gradual transition from H. erectus esatto Homo sapiens is one interpretation of the fossil supremazia, but the evidence also can be read differently. Many researchers have che puro accept what can be termed per punctuated view of human evolution. This view suggests that species such as H. erectus may have exhibited little or no morphological change over long periods of time (evolutionary stasis) and that the transition from one species to verso descendant form may have occurred relatively rapidly and sopra a restricted geographic distretto 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 to establish the range of physical variation of H. erectus and also for more discoveries durante good archaeological contexts to permit more precise dating. Additions to these two bodies of scadenza may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer puro resolution.
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