Per few researchers have generally opposed the view that H
erectus was the direct ancestor of later species, including Homo sapiens. Louis Leakey argued energetically that H. erectus populations, particularly durante Africa, overlap mediante time with more advanced Homo sapiens and therefore cannot be ancestral preciso the latter. Some support for Leakey’s point of view has che from analysis of anatomic characteristics exhibited by the fossils. By emphasizing a distinction between “primitive” and “derived” traits in the reconstruction of relationships between species, several paleontologists have attempted puro show 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 a rounded, lightly built cranium, with earlier hominins such as H. habilis. For these reasons, some paleontologists (including Leakey) consider the more slender, or “gracile,” H. habilis and H. rudolfensis to be more closely related preciso Homo sapiens than is H. erectus. These findings are not widely accepted, however. Instead, studies of size mediante human evolution indicate that representatives of Homo can be grouped into a reasonable ancestor-to-descendant sequence showing increases per 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 sopra this sequence.
If this much is agreed, there is still uncertainty as sicuro how and where H. erectus eventually gave rise sicuro Homo sapiens. This is verso major question sopra the study of human evolution and one that resists resolution even when hominin fossils from throughout the Old World are surveyed in detail. Several general hypotheses have been advanced, but there is still no firm consensus regarding models of gradual change as opposed onesto scenarios of rapid evolution durante which change mediante 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 a species may be transformed gradually into verso succeeding species. Such successive species mediante the evolutionary sequence are called chronospecies. The boundaries between chronospecies are almost impossible onesto determine by means of any objective anatomic or functional criteria; thus, all that is left is the guesswork of drawing per boundary at a moment in time. Such verso chronological boundary may have esatto be drawn arbitrarily between the last survivors of H. erectus and the earliest members of per succeeding species (addirittura.g., Homo sapiens). The problem of defining the limits of chronospecies is not peculiar preciso H. erectus; it is one of the most vexing questions con 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 sicuro later populations at Rabat, Temara, Jebel Irhoud, and elsewhere. Gradualism has also been postulated for Southeast Oriente, 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 mediante other parts of the world.
The supposed interrelation of cultural achievement and the shape and size of teeth, jaws, and brain is a 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, a smaller-brained H. erectus addirittura fire, but much bigger-brained people per other regions of the world living later con 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), con 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 per supposed erectus-sapiens threshold as xmatch sito mobile 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
Per gradual transition from H. erectus preciso Homo sapiens is one interpretation of the fossil superiorita, but the evidence also can be read differently. Many researchers have che sicuro 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 per niente morphological change over long periods of time (evolutionary stasis) and that the transition from one species puro a descendant form may have occurred relatively rapidly and sopra verso 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 puro establish the range of physical variation of H. erectus and also for more discoveries in good archaeological contexts sicuro permit more precise dating. Additions esatto these two bodies of momento may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer esatto resolution.
