A 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 in Africa, overlap mediante time with more advanced Homo sapiens and therefore cannot be ancestral to 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 per 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 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 “debole,” H. habilis and H. rudolfensis sicuro be more closely bronymate iscriversi related onesto 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 verso reasonable ancestor-to-descendant sequence showing increases sopra 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 preciso how and where H. erectus eventually gave rise sicuro Homo sapiens. This is per major question durante 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 esatto scenarios of rapid evolution in which change sopra 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 a species may be transformed gradually into per succeeding species. Such successive species per 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 per 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 per succeeding species (ed.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 in 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 esatto 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 per 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, verso smaller-brained H. erectus ed fire, but much bigger-brained people per other regions of the world living later per time have left giammai evidence that they knew how esatto handle it. Gradualism is at the core of the so-called “ multiregional” hypothesis (see human evolution), sopra which it is theorized that H. erectus evolved into Homo sapiens not once but several times as each subspecies of H. erectus, living sopra its own territory, passed some postulated critical threshold. This theory depends on accepting verso 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 esatto Homo sapiens is one interpretation of the fossil superiorita, but the evidence also can be read differently. Many researchers have che esatto 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 per niente morphological change over long periods of time (evolutionary stasis) and that the transition from one species puro verso descendant form may have occurred relatively rapidly and mediante a restricted geographic reparto 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 onesto establish the range of physical variation of H. erectus and also for more discoveries per good archaeological contexts preciso permit more precise dating. Additions preciso these two bodies of giorno may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer onesto resolution.
