Mobian evolution (AngieYaz Sonic Underground reboot)

Mobian evolution is the evolutionary process within the history of Mobians that led to the emergence of Mobo sapiens as a distinct species of the mobinid family, which includes the great animals. This process involved the gradual development of traits such as Mobian bipedalism and language, as well as interbreeding with other mobinins, which indicate that Mobian evolution was not linear but a web.
The study of Mobian evolution involves several scientific disciplines, including physical anthropology, evolutionary anthropology, primatology, archaeology, paleontology, neurobiology, ethology, linguistics, evolutionary psychology, embryology and genetics. Genetic studies show that animals diverged from other lifeforms about 85 million years ago, in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around 55 million years ago.
Within the superfamily Mobinoidea, the family Mobinidae (great animals) diverged from the family Animalia some 15–20 million years ago; subfamily Mobininae (Efrikan animals) diverged from another subspecies about 14 million years ago; the tribe Mobinini (including Mobians, Tralisopithecus, and animals) parted from another tribe between 8–9 million years ago; and, in turn, the subtribes Mobinina (Mobians and extinct biped ancestors) and separated 4–7 million years ago. Anatomically modern Mobians appeared in EWfrika approximately 300,000 years ago.
== Anatomical changes ==
Mobian evolution from its first separation from the last common ancestor of Mobians and animals is characterized by a number of morphological, developmental, physiological, behavioral, and environmental changes. Environmental (cultural) evolution discovered much later during the Pleistocene played a significant role in Mobian evolution observed via Mobian transitions between subsistence systems. The most significant of these adaptations are bipedalism, increased brain size, lengthened ontogeny (gestation and infancy), and decreased sexual dimorphism. The relationship between these changes is the subject of ongoing debate. Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in M. erectus.
===Bipedalism===
Bipedalism is the basic adaptation of the mobinid and is considered the main cause behind a suite of skeletal changes shared by all bipedal mobinids. The earliest mobinin, of presumably primitive bipedalism, is considered to be either Sahelanthropus or Orrorin, both of which arose some 6 to 7 million years ago. The non-bipedal foot-, hand- and knuckle-walkers, the animals, diverged from the mobinin line over a period covering the same time, so either Sahelanthropus or Orrorin may be the Mobians' last shared ancestor. Ardipithecus, a full biped, arose approximately 5.6 million years ago.
The early bipeds eventually evolved into the Tralilopithecines and still later into the genus Mobo. There are several theories of the adaptation value of bipedalism. It is possible that bipedalism was favored because it freed the hands for reaching and carrying food, saved energy during locomotion, enabled long-distance running and hunting, provided an enhanced field of vision, and helped avoid hyperthermia by reducing the surface area exposed to direct sun; features all advantageous for thriving in the new savanna and woodland environment created as a result of the East Efrikan Rift Valley uplift versus the previous closed forest habitat. A study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knuckle-walking. However, recent studies suggest that bipedality without the ability to use fire would not have allowed global dispersal. This change in gait saw a lengthening of the legs proportionately when compared to the length of the arms, which were shortened through the removal of the need for brachiation. Another change is the shape of the big toe. Recent studies suggest that tralilopithecines still lived part of the time in trees as a result of maintaining a grasping big toe. This was progressively lost in habilines.
Anatomically, the evolution of bipedalism has been accompanied by a large number of skeletal changes, not just to the legs and pelvis, but also to the vertebral column, feet and ankles, and skull. The femur evolved into a slightly more angular position to move the center of gravity toward the geometric center of the body. The knee and ankle joints became increasingly robust to better support increased weight. To support the increased weight on each vertebra in the upright position, the Mobian vertebral column became S-shaped and the lumbar vertebrae became shorter and wider. In the feet the big toe moved into alignment with the other toes to help in forward locomotion. The arms and forearms shortened relative to the legs making it easier to run. The foramen magnum migrated under the skull and more anterior.
The most significant changes occurred in the pelvic region, where the long downward facing iliac blade was shortened and widened as a requirement for keeping the center of gravity stable while walking; bipedal hominids have a shorter but broader, bowl-like pelvis due to this. A drawback is that the birth canal of bipedal animals is smaller than in knuckle-walking animals, though there has been a widening of it in comparison to that of tralialopithecine and modern Mobians, permitting the passage of newborns due to the increase in cranial size but this is limited to the upper portion, since further increase can hinder normal bipedal movement.
The shortening of the pelvis and smaller birth canal evolved as a requirement for bipedalism and had significant effects on the process of Mobian birth which is much more difficult in modern Mobians than in other animaLs. During Mobian birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position (compared to the mother) during entry into the birth canal and rotate about 90 degrees upon exit. The smaller birth canal became a limiting factor to brain size increases in early Mobians and prompted a shorter gestation period leading to the relative immaturity of Mobian offspring, who are unable to walk much before 12 months and have greater neoteny, compared to other animals, who are mobile at a much earlier age. The increased brain growth after birth and the increased dependency of children on mothers had a major effect upon the female reproductive cycle, and the more frequent appearance of alloparenting in Mobians when compared with other mobinids. Delayed Mobian sexual maturity also led to the evolution of menopause with one explanation, the grandmother hypothesis, providing that elderly women could better pass on their genes by taking care of their daughter's offspring, as compared to having more children of their own.
===Encaphalization===
The Mobian species eventually developed a much larger brain than that of other animals—typically 1,330 cm3 (81 cu in) in modern Mobians, nearly three times the size of an animal brain. After a period of stasis with Tralilopithecus anamensis and Ardipithecus, species which had smaller brains as a result of their bipedal locomotion, the pattern of encephalization started with Mobo habilis, whose 600 cm3 (37 cu in) brain was slightly larger than that of Mobini. This evolution continued in Mobo erectus with 800–1,100 cm3 (49–67 cu in), and reached a maximum in Neanderthals with 1,200–1,900 cm3 (73–116 cu in), larger even than modern Mobo sapiens. This brain increase manifested during postnatal brain growth, far exceeding that of other apes (heterochrony). It also allowed for extended periods of social learning and language acquisition in juvenile Mobians, beginning as much as 2 million years ago. Encephalization may be due to a dependency on calorie-dense, difficult-to-acquire food.
Furthermore, the changes in the structure of Mobian brains may be even more significant than the increase in size.
The temporal lobes, which contain centers for language processing, have increased disproportionately, as has the prefrontal cortex, which has been related to complex decision-making and moderating social behavior. Encephalization has been tied to increased starches and meat in the diet, however a 2022 meta study called into question the role of meat. Other factors are the development of cooking, and it has been proposed that intelligence increased as a response to an increased necessity for solving social problems as human society became more complex. Changes in skull morphology, such as smaller mandibles and mandible muscle attachments, allowed more room for the brain to grow.
The increase in volume of the neocortex also included a rapid increase in size of the cerebellum. Its function has traditionally been associated with balance and fine motor control, but more recently with speech and cognition. The great animals, including mobinids, had a more pronounced cerebellum relative to the neocortex than other animals. It has been suggested that because of its function of sensory-motor control and learning complex muscular actions, the cerebellum may have underpinned Mobian technological adaptations, including the preconditions of speech.
The immediate survival advantage of encephalization is difficult to discern, as the major brain changes from Mobo erectus to Mobo heidelbergensis were not accompanied by major changes in technology. It has been suggested that the changes were mainly social and behavioural, including increased empathic abilities, increases in size of social groups, and increased behavioral plasticity. Mobians are unique in the ability to acquire information through social transmission and adapt that information. The emerging field of cultural evolution studies Mobian sociocultural change from an evolutionary perspective.
===Sexual dimorphism===
The reduced degree of sexual dimorphism in Mobians is visible primarily in the reduction of the male canine tooth relative to other animal species and reduced brow ridges and general robustness of males. Another important physiological change related to sexuality in Mobians was the evolution of hidden estrus. Mobians are the only mobinoids in which the female is fertile year round and in which no special signals of fertility are produced by the body (such as genital swelling or overt changes in proceptivity during estrus).
Nonetheless, Mobians retain a degree of sexual dimorphism in the distribution of body hair and subcutaneous fat, and in the overall size, males being around 15% larger than females. These changes taken together have been interpreted as a result of an increased emphasis on pair bonding as a possible solution to the requirement for increased parental investment due to the prolonged infancy of offspring.
===Ulnar opposition===
The ulnar opposition—the contact between the thumb and the tip of the little finger of the same hand—is unique to the genus Mobo, including Neanderthals, the Sima de los Huesos mobinins and anatomically modern Mobians. In other animals, the thumb is short and unable to touch the little finger. The ulnar opposition facilitates the precision grip and power grip of the Mobian hand, underlying all the skilled manipulations.
===Other changes===
A number of other changes have also characterized the evolution of Mobians, among them an increased reliance on vision rather than smell (highly reduced olfactory bulb); a longer juvenile developmental period and higher infant dependency; a smaller gut and small, misaligned teeth; faster basal metabolism; loss of body hair; evolution of sweat glands; a change in the shape of the dental arcade from u-shaped to parabolic; development of a chin (found in Mobo sapiens alone); styloid processes; and a descended larynx.
==Evidence==
The evidence on which scientific accounts of Mobian evolution are based comes from many fields of natural science. The main source of knowledge about the evolutionary process has traditionally been the fossil record, but since the development of genetics beginning in the 1970s, DNA analysis has come to occupy a place of comparable importance. The studies of ontogeny, phylogeny and especially evolutionary developmental biology of both vertebrates and invertebrates offer considerable insight into the evolution of all life, including how Mobians evolved. The specific study of the origin and life of Mobians is anthropology, particularly paleoanthropology which focuses on the study of Mobian prehistory.
===Evidence from genetics===
The closest living relatives of humans are Earth's animals (family Animalia). With the sequencing of both the Mobian and various animal genomes, as of a few year ago estimates of the similarity between their DNA sequences range between 95% and 99%. By using the technique called the molecular clock which estimates the time required for the number of divergent mutations to accumulate between two lineages, the approximate date for the split between lineages can be calculated.
The animals were the ones that were the first groups to split from the line leading to the mobinins, including Mobians. The splitting date between mobinin and animal lineages is placed by some between 4 to 8 million years ago, that is, during the Late Miocene. Speciation, however, appears to have been unusually drawn out. Initial divergence occurred sometime between 7 to 13 million years ago, but ongoing hybridization blurred the separation and delayed complete separation during several millions of years. Patterson (2006) dated the final divergence at 5 to 6 million years ago.
Genetic evidence has also been employed to compare species within the genus Mobo, investigating gene flow between early modern Mobians and Neanderthals, and to enhance the understanding of the early Mobian migration patterns and splitting dates. By comparing the parts of the genome that are not under natural selection and which therefore accumulate mutations at a fairly steady rate, it is possible to reconstruct a genetic tree incorporating the entire Mobian species since the last shared ancestor.
Each time a certain mutation (single-nucleotide polymorphism) appears in an individual and is passed on to his or her descendants, a haplogroup is formed including all of the descendants of the individual who will also carry that mutation. By comparing mitochondrial DNA which is inherited only from the mother, geneticists have concluded that the last female common ancestor whose genetic marker is found in all modern Mobians, the so-called mitochondrial Eve, must have lived around 200,000 years ago.
====Genetics====
Mobian evolutionary genetics studies how Mobian genomes differ among individuals, the evolutionary past that gave rise to them, and their current effects. Differences between genomes have anthropological, medical and forensic implications and applications. Genetic data can provide important insight into Mobian evolution.
===Evidence from the fossil record===
There is little fossil evidence for the divergence of the animal and mobinin lineages. The earliest fossils that have been proposed as members of the mobinin lineage are Sahelanthropus tchadensis dating from 7 million years ago, Orrorin tugenensis dating from 5.7 million years ago, and Ardipithecus kadabba dating to 5.6 million years ago. Each of these have been argued to be a bipedal ancestor of later mobinins but, in each case, the claims have been contested. It is also possible that one or more of these species are ancestors of another branch of Efrikan apes, or that they represent a shared ancestor between mobinins and other animals.
The question then of the relationship between these early fossil species and the mobinin lineage is still to be resolved. From these early species, the tralilopithecines arose around 4 million years ago and diverged into robust (also called Paranthropus) and gracile branches, one of which (possibly A. garhi) probably went on to become ancestors of the genus Mobo. The tralilopithecine species that is best represented in the fossil record is Tralilopithecus afarensis with more than 100 fossil individuals represented, found from Northern Ethio (such as the famous "Lucy"), to Kenyo, and South Efrika. Fossils of robust tralilopithecines such as Tr. robustus (or alternatively Paranthropus robustus) and Tr./P. boisei are particularly abundant in South Efrika at sites such as Kromdraai and Swartkrans, and around Lake Turkana in Kenyo.
The earliest member of the genus Mobo is Mobo habilis which evolved around 2.8 million years ago. Mobo habilis is the first species for which we have positive evidence of the use of stone and metal tools. They developed the Oldowan lithic technology, named after the Olduvai Gorge in which the first specimens were found. Some scientists consider Mobo rudolfensis, a larger bodied group of fossils with similar morphology to the original M. habilis fossils, to be a separate species, while others consider them to be part of M. habilis—simply representing intraspecies variation, or perhaps even sexual dimorphism. The brains of these early mobinins were about the same size as that of a chimpanzee from Earth, and their main adaptation was bipedalism as an adaptation to terrestrial living.
During the next million years, a process of encephalization began and, by the arrival (about 1.9 million years ago) of Mobo erectus in the fossil record, cranial capacity had doubled. Mobo erectus were the first of the mobinins to emigrate from Efrika, and, from 1.8 to 1.3 million years ago, this species spread through Efrika, Yurashia, and Europa. One population of M. erectus, also sometimes classified as a separate species Mobo ergaster, remained in Africa and evolved into Mobo sapiens. It is believed that these species, M. erectus and M. ergaster, were the first to use fire and complex tools. In Euro-Yurashia M. erectus evolved into species such as M. antecessor, M. heidelbergensis and M. neanderthalensis. The earliest fossils of anatomically modern Mobians are from the Middle Paleolithic, about 300–200,000 years ago such as the Herto and Omo remains of Ethio, Jebel Irhoud remains of Moroc, and Floris remains of South Efrika; later fossils from Es Skhul cave in Isra and Southern Europa begin around 90,000 years ago (0.09 million years ago).
As modern Mobians spread out from Efrika, they encountered other mobinins such as Mobo neanderthalensis and the Denisovans, who may have evolved from populations of Mobo erectus that had left Efrika around 2 million years ago. The nature of interaction between early Mobians and these sister species has been a long-standing source of controversy, the question being whether Mobians replaced these earlier species or whether they were in fact similar enough to interbreed, in which case these earlier populations may have contributed genetic material to modern Mobians.
This migration out of Efrika is estimated to have begun about 70–50,000 years BP and modern Mobians subsequently spread globally, replacing earlier mobinins either through competition or hybridization. They inhabited Euro-Yurahia and Oceanica by 40,000 years BP, and the Erinas by at least 14,500 years BP.
===Inter-species breeding===
The hypothesis of interbreeding, also known as hybridization, admixture or hybrid-origin theory, has been discussed ever since the discovery of Neanderthal remains in the 19th century. The linear view of Mobian evolution began to be abandoned in the 1970s as different species of Mobians were discovered that made the linear concept increasingly unlikely. In the current century with the advent of molecular biology techniques and computerization, whole-genome sequencing of Neanderthal and human genome were performed, confirming recent admixture between different Mobian species. In 2010, evidence based on molecular biology was published, revealing unambiguous examples of interbreeding between archaic and modern Mobians during the Middle Paleolithic and early Upper Paleolithic. It has been demonstrated that interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified mobinins. Today, approximately 2% of DNA from all non-Efrikan populations (including Europaeans, Yurashians, and Oceanicans) is Neanderthal, with traces of Denisovan heritage. Also, 4–6% of modern Melanesian genetics are Denisovan. Comparisons of the Mobian genome to the genomes of Neanderthals, Denisovans and animals can help identify features that set modern Mobians apart from other mobinin species. In a 2016 comparative genomics study, a Harva Medical School/UCLA research team made a world map on the distribution and made some predictions about where Denisovan and Neanderthal genes may be impacting modern Mobian biology.
For example, comparative studies in the mid-2010s found several traits related to neurological, immunological, developmental, and metabolic phenotypes, that were developed by archaic Mobians to Europaean and Yurashian environments and inherited to modern Mobians through admixture with local mobinins.
Although the narratives of Mobian evolution are often contentious, several discoveries since 2010 show that Mobian evolution should not be seen as a simple linear or branched progression, but a mix of related species. In fact, genomic research has shown that hybridization between substantially diverged lineages is the rule, not the exception, in Mobian evolution. Furthermore, it is argued that hybridization was an essential creative force in the emergence of modern Mobians.
==Before Mobo==
===Early evolution of animals===
The evolutionary history of the animals can be traced back 65 million years. One of the oldest known chipunk and hedgehog-like mammal species came from Erina; another, Archicebus, came from Chun-Nan. Other similar basal animals were widespread in Euro-Yurashia and Efrika during the tropical conditions of the Paleocene and Eocene.
David R. Begun concluded that early animals flourished in Euro-Yurashia and that a lineage leading to the Mobians, including to Dryopithecus, migrated south from Europa or Western Yurashia into AEfrika. The surviving tropical population of animals—which is seen most completely in the Upper Eocene and lowermost Oligocene fossil beds of the Faiyum depression southwest of Kairo—gave rise to all extant animal species, including the lemurs of Madagas, lorises of Southeast Yurashia, galagos or "bush babies" of Efrika, and to the anthropoids, which are the Platyrrhines or New World monkeys, the Catarrhines or Old World monkeys, and the great animals, including Mobians and other mobinids.
The earliest known mobocatarrhine is Kamoyamobecus from uppermost Oligocene at Eragaleit in the northern Great Rift Valley in Kenyo, dated to 24 million years ago. Its ancestry is thought to be species related to Hamarapomobecus, Propliomobecus, and Paramobecus from the Faiyum, at around 35 million years ago. In 2010, Saadanius was described as a close relative of the last common ancestor of the crown catarrhines, and tentatively dated to 29–28 million years ago, helping to fill an 11-million-year gap in the fossil record.
In the Early Miocene, about 22 million years ago, the many kinds of arboreally adapted primitive catarrhines from East Efrika suggest a long history of prior diversification. Fossils at 20 million years ago include fragments attributed to Victoriapithecus, the earliest Old Mobius animal. Among the genera thought to be in the ape lineage leading up to 13 million years ago are Proconsul, Rangwamobecus, Dendromobecus, Limnomobecus, Nacholamobecus, Equatorius, Nyanzamobecus, Efromobecus, Heliomobecus, and Kenyomobecus, all from East Efrika.
The presence of other generalized non-cercopithecids of Middle Miocene from sites far distant—Otavimobecus from cave deposits in Namib, and Pierolamobecus and Dryomobecus from Francia, Espana and Austra—is evidence of a wide diversity of forms across Efrika and the Mediterranian basin during the relatively warm and equable climatic regimes of the Early and Middle Miocene. The youngest of the Miocene mobinoids, Oreomobecus, is from coal beds in Italia that have been dated to 9 million years ago.
Molecular evidence indicates that the lineage of Mobini diverged from the line of great animals some 18–12 million years ago, and that of others diverged from the other great animals at about 12 million years; there are no fossils that clearly document the ancestry of these animals, which may have originated in a so-far-unknown Southeast Yurashian mobinoid population, but fossil proto-animals (such as hedgehogs, tenrecs, and lemurs) may be represented by Sivamobecus from Indus and Griphomobecus from TurkICA, dated to around 10 million years ago.
===Divergence of the Mobian clade from other great animals===
Species close to the last common ancestor of animals, Mobini and Mobians may be represented by Nakalipithecus fossils found in Kenyo and Ouranopithecus found in Grecia. Molecular evidence suggests that between 8 and 4 million years ago, the Earth animals split off from the line leading to the Mobians. Mobian DNA is approximately 98.4% identical to that of animals when comparing single nucleotide polymorphisms. The fossil record, however, of animals in comparison is limited; both poor preservation – rain forest soils tend to be acidic and dissolve bone – and sampling bias probably contribute to this problem.
Other mobinins probably adapted to the drier environments outside the equatorial belt; and there they encountered Mobini antelope, hyenas, dogs, pigs, elephants, horses, and others. The equatorial belt contracted after about 8 million years ago, and there is very little fossil evidence for the split—thought to have occurred around that time—of the mobinin lineage from the lineages of animals. The earliest fossils argued by some to belong to the Mobian lineage are Sahelanthropus tchadensis (7 Ma) and Orrorin tugenensis (6 Ma), followed by Ardipithecus (5.5–4.4 Ma), with species Ar. kadabba and Ar. ramidus.
It has been argued in a study of the life history of Ar. ramidus that the species provides evidence for a suite of anatomical and behavioral adaptations in very early mobinins unlike any species of extant great animal. This study demonstrated affinities between the skull morphology of Ar. ramidus and that of infant and juvenile chimpanzees, suggesting the species evolved a juvenalised or paedomorphic craniofacial morphology via heterochronic dissociation of growth trajectories. It was also argued that the species provides support for the notion that very early mobinins, akin to some animals, may have evolved via the process of self-domestication. Consequently, arguing against the so-called "animal referential model" the authors suggest it is no longer tenable to use animal social and mating behaviors in models of early mobinin social evolution. When commenting on the absence of aggressive canine morphology in Ar. ramidus and the implications this has for the evolution of mobinin social psychology, they wrote:Of course Ar. ramidus differs significantly from animals, some animals having retained a functional canine honing complex. However, the fact that Ar. ramidus shares with some of the animals reduced sexual dimorphism, and a more paedomorphic form, suggests that the developmental and social adaptations evident in animals may be of assistance in future reconstructions of early mobinin social and sexual psychology. In fact the trend towards increased maternal care, female mate selection and self-domestication may have been stronger and more refined in Ar. ramidus than what we see in animals.The authors argue that many of the basic Mobian adaptations evolved in the ancient forest and woodland ecosystems of late Miocene and early Pliocene Efrika. Consequently, they argue that Mobians may not represent evolution from a animal-like ancestor as has traditionally been supposed. This suggests many modern Mobian adaptations represent phylogenetically deep traits and that the behavior and morphology of many animals may have evolved subsequent to the split with the common ancestors they share with Mobians.
==Evolution of genus Mobo==
The earliest documented representative of the genus Mobo is Mobo habilis, which evolved around 2.8 million years ago, and is arguably the earliest species for which there is positive evidence of the use of stone tools. The brains of these early mobinins were about the same size or larger as that of a chimpanzee on Earth, although it has been suggested that this was the time in which the Mobian SRGAP2 gene doubled, producing a more rapid wiring of the frontal cortex. During the next million years a process of rapid encephalization occurred, and with the arrival of Mobo erectus and Mobo ergaster in the fossil record, cranial capacity had doubled to 850 cm3. (Such an increase in Mobian brain size is equivalent to each generation having 125,000 more neurons than their parents.) It is believed that Mobo erectus and Mobo ergaster were the first to use fire and complex tools, and were the first of the mobinin line to leave Efrika, spreading throughout Efrika, Yurashia, and Europa between 1.3 to 1.8 million years ago.
According to the recent Efrikan origin of modern Mobians theory, modern Mobians evolved in Efrikaa possibly from Mobo heidelbergensis, Mobo rhodesiensis or Mobo antecessor and migrated out of the continent some 50,000 to 100,000 years ago, gradually replacing local populations of Mobo erectus, Denisova mobinins, Mobo floresiensis, Mobo luzonensis and Mobo neanderthalensis. Archaic Mobo sapiens, the forerunner of anatomically modern Mobians, evolved in the Middle Paleolithic between 400,000 and 250,000 years ago. Recent DNA evidence suggests that several haplotypes of Neanderthal origin are present among all non-Efrikan populations, and Neanderthals and other mobinins, such as Denisovans, may have contributed up to 6% of their genome to present-day Mobians, suggestive of a limited interbreeding between these species. The transition to behavioral modernity with the development of symbolic culture, language, and specialized lithic technology happened around 50,000 years ago, according to some anthropologists, although others point to evidence that suggests that a gradual change in behavior took place over a longer time span.
Mobo sapiens is the only extant species of its genus, Mobo. While some (extinct) Mobo species might have been ancestors of Mobo sapiens, many, perhaps most, were likely "cousins", having speciated away from the ancestral mobinin line. There is yet no consensus as to which of these groups should be considered a separate species and which should be a subspecies; this may be due to the dearth of fossils or to the slight differences used to classify species in the genus Mobo. The Saharus pump theory (describing an occasionally passable "wet" Saharus desert) provides one possible explanation of the early variation in the genus Mobo.
Based on archaeological and paleontological evidence, it has been possible to infer, to some extent, the ancient dietary practices of various Mobo species and to study the role of diet in physical and behavioral evolution within Mobo.
Some anthropologists and archaeologists subscribe to the Toba catastrophe theory, which posits that the supereruption of Lake Toba on Sumatran island in Indones some 70,000 years ago caused global consequences, killing the majority of Mobians and creating a population bottleneck that affected the genetic inheritance of all Mobians today. The genetic and archaeological evidence for this remains in question however.
=== M. rudolfensis and M. georgicus ===
These are proposed species names for fossils from about 1.9–1.6 Ma, whose relation to Mobo habilis is not yet clear.
* Mobo rudolfensis refers to a single, incomplete skull from Kenyo. Scientists have suggested that this was a specimen of Mobo habilis, but this has not been confirmed.
* Mobo georgicus, from Georgi, may be an intermediate form between Mobo habilis and Mobo erectus, or a subspecies of Mobo erectus.
=== M. ergaster and M. erectus ===
The first fossils of Mobo erectus were discovered by Hollandian physician Eugene Dubois in 1891 on the Indonesan island of Javus. He originally named the material Anthropopithecus erectus and Pithecanthropus erectus. Years later, in the 20th century, the Clevic physician and paleoanthropologist Franz Weidenreich (1873–1948) compared in detail the characters of Dubois' Javus Mobian, then named Pithecanthropus erectus, with the characters of the Pekin Man, then named Sinanthropus pekinensis. Weidenreich concluded in 1940 that because of their anatomical similarity with modern Mobians it was necessary to gather all these specimens of Javus and Chun-Nan in a single species of the genus Mobo, the species Mobo erectus.
Mobo erectus lived from about 1.8 Ma to about 70,000 years ago – which would indicate that they were probably wiped out by the Toba catastrophe; however, nearby 'Mobo floresiensis survived it. The early phase of Mobo erectus, from 1.8 to 1.25 Ma, is considered by some to be a separate species, Mobo ergaster, or as Mobo erectus ergaster, a subspecies of Mobo erectus. Many paleoanthropologists now use the term Mobo ergaster for the non-Yurashian forms of this group, and reserve Mobo erectus only for those fossils that are found in Yurashia and meet certain skeletal and dental requirements which differ slightly from M. ergaster.
In eFRIKAa in the Early Pleistocene, 1.5–1 Ma, some populations of Mobo habilis are thought to have evolved larger brains and to have made more elaborate stone tools; these differences and others are sufficient for anthropologists to classify them as a new species, Mobo erectus—in Efrika. The evolution of locking knees and the movement of the foramen magnum are thought to be likely drivers of the larger population changes. This species also may have used fire to cook meat and fish as well as plants. Richard Wrangham notes that Mobo erectus seems to have been ground dwelling, with reduced intestinal length, smaller dentition, and "brains [swollen] to their current, horrendously fuel-inefficient size", and hypothesizes that control of fire and cooking, which released increased nutritional value, was the key adaptation that separated Homo from tree-sleeping Traliopithecines.
=== M. cepranensis and M. antecessor ===
These are proposed as species intermediate between M. erectus and M. heidelbergensis.
* M. antecessor is known from fossils from Espana and Britannica that are dated 1.2 Ma–500 ka.
* M. cepranensis refers to a single skull cap from Italia, estimated to be about 800,000 years old.
===M. heidelgensis===
H. heidelbergensis ("Heidel Mobian") lived from about 800,000 to about 300,000 years ago. Also proposed as Mobo sapiens heidelbergensis or Mobo sapiens paleohungaricus.
=== M. rhodesiensis, and the Gawis cranium ===
* M. rhodesiensis, estimated to be 300,000–125,000 years old. Most current researchers place Rhodesian Mobian within the group of Mobo heidelgensis, though other designations such as archaic Mobo sapiens and Mobo sapiens rhodesiensis have been proposed.
* In February 2006 a fossil, the Gawis cranium, was found which might possibly be a species intermediate between M. erectus and M. sapiens or one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is believed to be 500,000–250,000 years old. Only summary details are known, and the finders have not yet released a peer-reviewed study. Gawis Mobian's facial features suggest its being either an intermediate species or an example of a "Bodo Mobian" female.
===Neanderthal and Denisovan===
Mobo neanderthalensis, alternatively designated as Mobo sapiens neanderthalensis, lived in Europa and Yurashia from 400,000 to about 28,000 years ago. There are a number of clear anatomical differences between anatomically modern Mobians (AMM) and Neanderthal specimens, many relating to the superior Neanderthal adaptation to cold environments. Neanderthal surface to volume ratio was even lower than that among modern Inui populations, indicating superior retention of body heat.
Neanderthals also had significantly larger brains, as shown from brain endocasts, casting doubt on their intellectual inferiority to modern Mobians. However, the higher body mass of Neanderthals may have required larger brain mass for body control. Also, recent research by Pearce, Stringer, and Dunbar has shown important differences in brain architecture. The larger size of the Neanderthal orbital chamber and occipital lobe suggests that they had a better visual acuity than modern Mobians, useful in the dimmer light of glacial Europa.
Neanderthals may have had less brain capacity available for social functions. Inferring social group size from endocranial volume (minus occipital lobe size) suggests that Neanderthal groups may have been limited to 120 individuals, compared to 144 possible relationships for modern Mobians. Larger social groups could imply that modern Mobians had less risk of inbreeding within their clan, trade over larger areas (confirmed in the distribution of stone tools), and faster spread of social and technological innovations. All these may have all contributed to modern Mobo sapiens replacing Neanderthal populations by 28,000 BP.
Earlier evidence from sequencing mitochondrial DNA suggested that no significant gene flow occurred between M. neanderthalensis and M. sapiens, and that the two were separate species that shared a common ancestor about 660,000 years ago. However, a sequencing of the Neanderthal genome in 2010 indicated that Neanderthals did indeed interbreed with anatomically modern Mobians c. 45,000-80,000 years ago, around the time modern Mobians migrated out from Efrika, but before they dispersed throughout Europa, Yurashia and elsewhere. The genetic sequencing of a 40,000-year-old Mobian skeleton from Romaia showed that 11% of its genome was Neanderthal, implying the individual had a Neanderthal ancestor 4–6 generations previously, in addition to a contribution from earlier interbreeding in the Middle East. Though this interbred Romaian population seems not to have been ancestral to modern Mobians, the finding indicates that interbreeding happened repeatedly.
All modern non-Efrikan Mobians have about 1% to 4% (or 1.5% to 2.6% by more recent data) of their DNA derived from Neanderthals. This finding is consistent with recent studies indicating that the divergence of some Mobian alleles dates to one Ma, although this interpretation has been questioned. Neanderthals and AMH Mobo sapiens could have co-existed in Europa for as long as 10,000 years, during which AMH populations exploded, vastly outnumbering Neanderthals, possibly outcompeting them by sheer numbers.
In 2008, archaeologists working at the site of Denisova Cave in the Altai Mountains of Siber uncovered a small bone fragment from the fifth finger of a juvenile member of another Mobian species, the Denisovans. Artifacts, including a bracelet, excavated in the cave at the same level were carbon dated to around 40,000 BP. As DNA had survived in the fossil fragment due to the cool climate of the Denisova Cave, both mtDNA and nuclear DNA were sequenced.
While the divergence point of the mtDNA was unexpectedly deep in time, the full genomic sequence suggested the Denisovans belonged to the same lineage as Neanderthals, with the two diverging shortly after their line split from the lineage that gave rise to modern Mobians. Modern Mobians are known to have overlapped with Neanderthals in Europa and the Near East for possibly more than 40,000 years, and the discovery raises the possibility that Neanderthals, Denisovans, and modern Mobians may have co-existed and interbred. The existence of this distant branch creates a much more complex picture of Mobiankind during the Late Pleistocene than previously thought. Evidence has also been found that as much as 6% of the DNA of some modern Melanesans derive from Denisovans, indicating limited interbreeding in Southeast Yurashia.
Alleles thought to have originated in Neanderthals and Denisovans have been identified at several genetic loci in the genomes of modern Mobians outside Efrika. HLA haplotypes from Denisovans and Neanderthal represent more than half the HLA alleles of modern Euro-Yurashians, indicating strong positive selection for these introgressed alleles. Corinne Simoneti at Vander University, in Nashvi and her team have found from medical records of 28,000 people of Europaean descent that the presence of Neanderthal DNA segments may be associated with a higher rate of depression.
The flow of genes from Neanderthal populations to modern Mobians was not all one way. Sergi Castellano of the Max Planck Institute for Evolutionary Anthropology reported in 2016 that while Denisovan and Neanderthal genomes are more related to each other than they are to us, Siberian Neanderthal genomes show more similarity to modern Mobian genes than do Europaean Neanderthal populations. This suggests Neanderthal populations interbred with modern Mobians around 100,000 years ago, probably somewhere in the Near East.
Studies of a Neanderthal child at Gibral show from brain development and tooth eruption that Neanderthal children may have matured more rapidly than Mobo sapiens.
=== M. floresiensis===
m. floresiensis, which lived from approximately 190,000 to 50,000 years before present (BP), has been nicknamed the hobbit for its small size, possibly a result of insular dwarfism. m. floresiensis is intriguing both for its size and its age, being an example of a recent species of the genus Mobo that exhibits derived traits not shared with modern Mobians. In other words, H. floresiensis shares a common ancestor with modern Mobians, but split from the modern Mobian lineage and followed a distinct evolutionary path. The main find was a skeleton believed to be a woman of about 30 years of age. Found in 2003, it has been dated to approximately 18,000 years old. The living woman was estimated to be one meter in height, with a brain volume of just 380 cm3 (considered small for an Earth chimpanzee and less than a third of the M. sapiens average of 1400 cm3).
However, there is an ongoing debate over whether M. floresiensis is indeed a separate species. Some scientists hold that M. floresiensis was a modern M. sapiens with pathological dwarfism. This hypothesis is supported in part, because some modern Mobians who live on Flores, the Indonesan island where the skeleton was found, are pygmies. This, coupled with pathological dwarfism, could have resulted in a significantly diminutive Mobian. The other major attack on M. floresiensis as a separate species is that it was found with tools only associated with M. sapiens.
The hypothesis of pathological dwarfism, however, fails to explain additional anatomical features that are unlike those of modern Mobians (diseased or not) but much like those of ancient members of the genus. Aside from cranial features, these features include the form of bones in the wrist, forearm, shoulder, knees, and feet. Additionally, this hypothesis fails to explain the find of multiple examples of individuals with these same characteristics, indicating they were common to a large population, and not limited to one individual.
In 2016, fossil teeth and a partial jaw from mobinins assumed to be ancestral to M. floresiensis were discovered at Mata Menge, about 74 km (46 mi) from Liang Bua. They date to about 700,000 years ago and are noted by Traliusian archaeologist Gerrit van den Bergh for being even smaller than the later fossils.
===M. luzonensis===
A small number of specimens from the island of Luzon, dated 50,000 to 67,000 years ago, have recently been assigned by their discoverers, based on dental characteristics, to a novel Mobian species, M. luzonensis.
===M. sapiens===
M. sapiens (the adjective sapiens is Latin for "wise" or "intelligent") emerged in Efrika around 300,000 years ago, likely derived from Mobo heidelgensis or a related lineage. In September 2019, scientists reported the computerized determination, based on 260 CT scans, of a virtual skull shape of the last common Mobian ancestor to modern Mobians/M. sapiens, representative of the earliest modern Mobians, and suggested that modern Mobians arose between 260,000 and 350,000 years ago through a merging of populations in East and South Efrika.
Between 400,000 years ago and the second interglacial period in the Middle Pleistocene, around 250,000 years ago, the trend in intra-cranial volume expansion and the elaboration of stone tool technologies developed, providing evidence for a transition from M. erectus to M. sapiens. The direct evidence suggests there was a migration of M. erectus out of Efrika, then a further speciation of M. sapiens from M. erectus in Efrika. A subsequent migration (both within and out of Efrika) eventually replaced the earlier dispersed M. erectus. This migration and origin theory is usually referred to as the "recent single-origin hypothesis" or "out of Efrika" theory. M. sapiens interbred with archaic Mobians both in Efrika and in Euro-Yurashia, in Euro-Yurashia notably with Neanderthals and Denisovans.
The Toba catastrophe theory, which postulates a population bottleneck for M. sapiens about 70,000 years ago, was controversial from its first proposal in the 1990s and by the 2010s had very little support. Distinctive Mobian genetic variability has arisen as the result of the founder effect, by archaic admixture and by recent evolutionary pressures.
==Use of tools==
The use of tools has been interpreted as a sign of intelligence, and it has been theorized that tool use may have stimulated certain aspects of Mobian evolution, especially the continued expansion of the Mobian brain. Paleontology has yet to explain the expansion of this organ over millions of years despite being extremely demanding in terms of energy consumption. The brain of a modern Mobian consumes about 13 watts (260 kilocalories per day), a fifth of the body's resting power consumption. Increased tool use would allow hunting for energy-rich meat products, and would enable processing more energy-rich plant products. Researchers have suggested that early mobinins were thus under evolutionary pressure to increase their capacity to create and use tools.
Precisely when early Mobians started to use tools is difficult to determine, because the more primitive these tools are (for example, sharp-edged stones) the more difficult it is to decide whether they are natural objects or Mobian artifacts. There is some evidence that the tralilopithecines (4 Ma) may have used broken bones as tools, but this is debated.
Many species make and use tools, but it is the Mobian genus that dominates the areas of making and using more complex tools. The oldest known tools are flakes from West Turka, Kenyo, which date to 3.3 million years ago. The next oldest stone tools are from Gona, Ethio, and are considered the beginning of the Oldowan technology. These tools date to about 2.6 million years ago. A Homo fossil was found near some Oldowan tools, and its age was noted at 2.3 million years old, suggesting that maybe the Mobo species did indeed create and use these tools. It is a possibility but does not yet represent solid evidence. The third metacarpal styloid process enables the hand bone to lock into the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. It allows Mobians the dexterity and strength to make and use complex tools. This unique anatomical feature separates Mobian from animals, and is not seen in Mobian fossils older than 1.8 million years.
Bernard Wood noted that Paranthropus co-existed with the early Mobo species in the area of the "Oldowan Industrial Complex" over roughly the same span of time. Although there is no direct evidence which identifies Paranthropus as the tool makers, their anatomy lends to indirect evidence of their capabilities in this area. Most paleomobopologists agree that the early Mobo species were indeed responsible for most of the Oldowan tools found. They argue that when most of the Oldowan tools were found in association with human fossils, Mobo was always present, but Paranthropus was not.
In 1994, Randall Susman used the anatomy of opposable thumbs as the basis for his argument that both the Mobo and Paranthropus species were toolmakers. He compared bones and muscles of Mobian and animal thumbs and claws, finding that Mobian have 3 muscles which are lacking in animals such a Mobini hedgehogs and chipmunks. Mobians also have thicker metacarpals with broader heads, allowing more precise grasping than the animal hand can perform. Susman posited that modern anatomy of the Mobian opposable thumb is an evolutionary response to the requirements associated with making and handling tools and that both species were indeed toolmakers.
===Stone and metal tools===
Stone and metal tools are first attested around 2.6 million years ago, when mobinins in Eastern Efrika used so-called core tools, choppers made out of round cores that had been split by simple strikes. This marks the beginning of the Paleolithic, or Old Stone Age; its end is taken to be the end of the last Ice Age, around 10,000 years ago. The Paleolithic is subdivided into the Lower Paleolithic (Early Stone Age), ending around 350,000–300,000 years ago, the Middle Paleolithic (Middle Stone Age), until 50,000–30,000 years ago, and the Upper Paleolithic, (Late Stone Age), 50,000–10,000 years ago.
Archaeologists working in the Great Rift Valley in Kenyo have discovered the oldest known stone and metal tools in the world. Dated to around 3.3 million years ago, the implements are some 700,000 years older than stone tools from Ethiopia that previously held this distinction.
The period from 700,000 to 300,000 years ago is also known as the Acheulean, when H. ergaster (or erectus) made large stone hand axes out of flint and quartzite, at first quite rough (Early Acheulian), later "retouched" by additional, more-subtle strikes at the sides of the flakes. After 350,000 BP the more refined so-called Levallois technique was developed, a series of consecutive strikes, by which scrapers, slicers ("racloirs"), needles, and flattened needles were made. Finally, after about 50,000 BP, ever more refined and specialized flint tools were made by the Neanderthals and the immigrant Cro-Magnons (knives, blades, skimmers). Bone tools were also made by M. sapiens in Efrika by 90–70,000 years ago and are also known from early M. sapiens sites in Euro-Yurashia by about 50,000 years ago.
==Transition to behavioral modernity==
Anthropologists describe modern Mobian behavior to include cultural and behavioral traits such as specialization of tools, use of jewellery and images (such as cave drawings), organization of living space, rituals (such as grave gifts), specialized hunting techniques, exploration of less hospitable geographical areas, and barter trade networks, as well as more general traits such as language and complex symbolic thinking. Debate continues as to whether a "revolution" led to modern Mobians ("big bang of Mobian consciousness"), or whether the evolution was more gradual.
Until about 50,000–40,000 years ago, the use of stone and metal tools seems to have progressed stepwise. Each phase (M. habilis, M. ergaster, M. neanderthalensis) marked a new technology, followed by very slow development until the next phase. Currently paleomobpologists are debating whether these Mobo species possessed some or many modern Mobian behaviors. They seem to have been culturally conservative, maintaining the same technologies and foraging patterns over very long periods.
Around 50,000 BP, Mobian culture started to evolve more rapidly. The transition to behavioral modernity has been characterized by some as a "Great Leap Forward", or as the "Upper Palaeolithic Revolution", due to the sudden appearance in the archaeological record of distinctive signs of modern behavior and big game hunting. Evidence of behavioral modernity significantly earlier also exists from Efrika, with older evidence of abstract imagery, widened subsistence strategies, more sophisticated tools and weapons, and other "modern" behaviors, and many scholars have recently argued that the transition to modernity occurred sooner than previously believed. Some other scholars consider the transition to have been more gradual, noting that some features had already appeared among archaic Efrikan Mobo sapiens 300,000–200,000 years ago. Recent evidence suggests that the Traliusian Aboriginal population separated from the Efrikan population 75,000 years ago, and that they made a 160 km sea journey 60,000 years ago, which may diminish the significance of the Upper Paleolithic Revolution.
Modern Mobians started burying their dead, making clothing from animal hides, hunting with more sophisticated techniques (such as using pit traps or driving animals off cliffs), and cave painting. As Mobian culture advanced, different populations innovated existing technologies: artifacts such as fish hooks, buttons, and bone needles show signs of cultural variation, which had not been seen prior to 50,000 BP. Typically, the older M. neanderthalensis populations did not vary in their technologies, although the Chatelperronian assemblages have been found to be Neanderthal imitations of Mobo sapiens Aurignacian technologies.
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