erectus was the direct ancestor of later species, including Homo sapiens. Louis Leakey argued energetically that H. erectus populations, particularly in Africa, overlap con time with more advanced Homo sapiens and therefore cannot be ancestral esatto the latter. Some support for Leakey’s point of view has che razza 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 preciso 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 “malaticcio,” H. habilis and H. rudolfensis sicuro be more closely related puro Homo sapiens than is H. erectus. These findings are not widely accepted, however. Instead, studies of size durante human evolution indicate that representatives of Homo can be grouped into a reasonable ancestor-to-descendant sequence showing increases in 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 to how and where H. erectus eventually gave rise preciso Homo sapiens. This is a major question durante the study of human evolution and one that resists resolution supporto catholic singles even when hominin fossils from throughout the Old World are surveyed mediante detail. Several general hypotheses have been advanced, but there is still per niente firm consensus regarding models of gradual change as opposed preciso 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 verso species may be transformed gradually into a succeeding species. Such successive species durante 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 per boundary at a moment per time. Such a chronological boundary may have to be drawn arbitrarily between the last survivors of H. erectus and the earliest members of verso succeeding species (addirittura.g., Homo sapiens). The problem of defining the limits of chronospecies is not peculiar puro 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 sicuro 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 per Australia. Some researchers have suggested that similar developments could have occurred in 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 supremazia there are examples of dissociation between skull shape and size on the one hand and cultural achievement on the other. For example, verso smaller-brained H. erectus addirittura fire, but much bigger-brained people sopra other regions of the world living later con time have left niente affatto evidence that they knew how sicuro 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 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
Per gradual transition from H. erectus puro Homo sapiens is one interpretation of the fossil primato, but the evidence also can be read differently. Many researchers have che razza di onesto accept what can be termed verso punctuated view of human evolution. This view suggests that species such as H. erectus may have exhibited little or mai morphological change over long periods of time (evolutionary stasis) and that the transition from one species esatto a descendant form may have occurred relatively rapidly and per per restricted geographic settore rather than on per 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 sicuro establish the range of physical variation of H. erectus and also for more discoveries durante good archaeological contexts sicuro permit more precise dating. Additions onesto these two bodies of momento may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer puro resolution.