erectus was the direct ancestor of later species, including Homo sapiens. Louis Leakey argued energetically that H. erectus populations, particularly mediante Africa, overlap per time with more advanced Homo sapiens and therefore cannot be ancestral to the latter. Some support for Leakey’s point of view has ad esempio from analysis of anatomic characteristics exhibited by the fossils. By emphasizing a distinction between “primitive” and “derived” traits per the reconstruction of relationships between species, several paleontologists have attempted preciso show that H. erectus does not make a suitable morphological ancestor for Homo sapiens. Because the braincase is long, low, and thick-walled and presents verso 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 “malaticcio,” H. habilis and H. rudolfensis onesto be more closely related puro Homo sapiens than is H. erectus. These findings http://datingranking.net/it/catholicmatch-review/ are not widely accepted, however. Instead, studies of size mediante human evolution indicate that representatives of Homo can be grouped into per reasonable ancestor-to-descendant sequence showing increases in 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 con this sequence.
If this much is agreed, there is still uncertainty as preciso how and where H. erectus eventually gave rise puro Homo sapiens. This is per major question in 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 no firm consensus regarding models of gradual change as opposed sicuro scenarios of rapid evolution in which change con one region is followed by migration of the new populations into other areas.
Theories of gradual change
A traditional view held by some paleontologists is that a species may be transformed gradually into per succeeding species. Such successive species mediante the evolutionary sequence are called chronospecies. The boundaries between chronospecies are almost impossible sicuro determine by means of any objective anatomic or functional criteria; thus, all that is left is the guesswork of drawing a boundary at per moment durante time. Such per chronological boundary may have esatto be drawn arbitrarily between the last survivors of H. erectus and the earliest members of per succeeding species (ancora.g., Homo sapiens). The problem of defining the limits of chronospecies is not peculiar esatto 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 esatto 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 in 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 per 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 ancora fire, but much bigger-brained people mediante other regions of the world living later sopra 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), in 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 onesto Homo sapiens is one interpretation of the fossil superiorita, but the evidence also can be read differently. Many researchers have quale 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 no morphological change over long periods of time (evolutionary stasis) and that the transition from one species esatto verso descendant form may have occurred relatively rapidly and durante per restricted geographic dipartimento 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 esatto establish the range of physical variation of H. erectus and also for more discoveries mediante good archaeological contexts preciso permit more precise dating. Additions to these two bodies of tempo may settle remaining questions and bring the problems surrounding the evolution of H. erectus nearer onesto resolution.
Leave a Reply