The first fossil Asian ape was found in 1879 in the Potwar Plateau, the Western molasse of the Siwaliks bordered by the Indus River and crossed by the Soan River. Lyddeker named the specimen Sivapithecus well before the discovery in 1933 of the Proconsul in Kenya, Eastern Africa. In 1934, Lewis collected a partial maxillary in the Miocene formations of Himachal Pradesh at Haritalyangar, 80 km north-west of Masol (31° 32’ N, 76°38’ E) (Fig. 1C, Fig. 2, Fig. 3A and B). The famous YPM 13799 (Yale Peabody Museum) was assigned to a new genus, Ramapithecus brevirostris, because of its prognathism apparently less developed than Sivapithecus, Lewis proposed to consider the new fossil as an ancestor of the genus Homo. The Upper Indus Basin and the Himalayan foothills became the cradle of humankind up to the 1970s thanks to the works of Simons and Pilbeam; nevertheless the maxillary YPM 13799 was reclassified as a Sivapithecus (for a review see Kelley, 1988, Patnaik and Chauhan, 2009, Pillans et al., 2005 and Vogel, 1975). The primate list of Haritalyangar was completed by the discovery of a mandible of a large species Indopithecus giganteus (CYP 359/68, Chandigarh Yale Paleontology), the magnetostratigraphy dating this assemblage from the Dhok Pathan Formation, to 8.5 Ma (Patnaik and David, 2007), while other analyses concluded that “the sedimentary environments and fauna suggest that Haritalyangar primates lived within a river floodplain setting, which included open forest vegetation with patches of bamboo, in a seasonally wet sub-humid to semi-arid climate” (Pillans et al., 2005). The absence of apes in the fossiliferous formations of late Pliocene (Tatrot) has been interpreted as “the extinction of Sivapithecus in the Siwaliks linked to fragmentation of its forest habitat in response to decreasing rainfall” (Pillans et al., 2005). However, Sankhyan (2011) has put forward counter-arguments, this question is debated in the paragraph 8 “Research perspective”.

In 1947, the karsts of Makapan Valley, South Africa, yielded new fossils named Australopithecus africanus, dating from between 3.0 and 2.6 Ma, attesting to a very clear verticalisation of the axial skeleton since the hypophyseal fossa (the pituitary lodge) that imposed an osteo-skeletal architecture in permanent bipedal posture as shown by the pelvis. These skeletons had no equivalent among extant and fossil great ape species, paleontologists saw a transitory grade between the apes – semi-erected from the hypophyseal fossa to the sacrum, quadrumanous and occasionally bipedal – and the Homo genus, with the cerebral trunk and the spinal-cord completely verticalized, consecutively bimanous and bipedal. Others such as the world-renowned geologist-paleontologist Teilhard de Chardin (1881-1955), and counselor of the Wenner-Gren Foundation in the early 1950s, considered Australopithecus as a parallel phylum to the Homo lineage. The face looked ape-like and the brain endocast seemed too small to represent the inventor of the tools collected in Makapansgat. For the French paleontologist, who had studied the “granitization” – or “continentalisation” – of China, travelled extensively in India, Burma and Java, and contributed to the development of prehistory in Asia, the old lithic industries of Makapansgat, exemplified the emergence of Homo very close to Australopithecus, inducing his conviction of the South-African origins of the human lineage.

Teilhard de Chardin was looking for a geophysical theory of the Homo origins, i.e. dependent on the formation of the continents and their accretions which, consequently, modified the climatic conditions and forced the species to evolve together (the theory of continental drift was not accepted at this epoch). Man, wrote Teilhard, was born “of the double caprice of genes” during the “favorable conditions” created by the “shape of the continents” (Teilhard de Chardin, 1949). The theoretician of the evolutionary processes combined the growing complexity of the terrestrial organisms to the “granitization” of the planet because of its spherical surface which constituted a planetary constraint, a closed system. As a specialist in Tertiary mammals, and especially of the first primates (Omomyideae), and, in contact with the anthropologists specialists in Asian Homo erectus (Sinanthropus and Pithecanthropus), Teilhard was able to observe how the primates had distinguished themselves among mammals, from the Tertiary up to the Quaternary, in particular, with respect to the complexification of the cerebral neocortex with Homo erectus and later Homo sapiens. At that time, paleoanthropologists described a process of “telencephalisation”, or the increasing complexity of the more anterior vesicle of the embryonic neural tube (Dambricourt Malassé, 1988).

The increasing complexity of the telencephalon (cerebral hemispheres) is the directing wire of the Teilhard's geolamarckian theory on human origins, affirmed, in particular, by Jean Piveteau (1899-1991), the founder in 1938 of the Chair of Vertebrates and Human Paleontology at the Sorbonne University, Paris, where Teilhard taught the late 1940s. His scientific inheritance is transmitted in France thanks to world-renowned Professors from the National Museum of Natural History, Yves Coppens, 2006 and Coppens, 2014, former Head Laboratory of Anthropology, and Henry de Lumley, former Head Laboratory of Prehistory (Dambricourt Malassé, 2004a). Indeed, the scientific theory of Teilhard de Chardin is capable to embrace the very long durations at the continental scales, taking into account not only the anatomical adaptations to global climate changes, but also the increasing complexity of the central nervous system up to the emergence of the reflexive consciousness.

Anthropologists and primatologists agree that this complexity expected in the fossil record, refers to a brain organization, sufficiently developed and irrigated by vascularisation, to allow a reflection of information so effective that it results in the emergence of symbolic and conceptual thought. But this cephalic organization must, necessarily, be accompanied by a neuroanatomical system allowing eye-hand coordination in order to shape an object to the image of the abstract project.

A new chapter opened in 1974-1975, which focused on the adaptation of the locomotor apparatus, or appendicular skeleton, with the discovery of Australopithecus in the Afar Depression in Ethiopia, where the dislocation of the African plate creates a new oceanic floor. The East-African rift became the geophysical hypothesis linking the shape of the continents, the climate and the origins of hominines with the theory of Yves Coppens, “(H)omo Event” (origin of the genus Homo) and “The East Side Story” (origin of the genus Australopithecus) (Coppens, 1975, Coppens, 1976, Coppens, 1978, Coppens, 1979, Coppens, 1980 and Coppens, 1981).

The emphasis on locomotion began to show an anatomical evolution more complicated than the scenario of the verticality origins, as imagined by Lamarck (1802) and, subsequently, taken over by Darwin (1871), namely, a slow and gradual post-natal acquisition with inheritance of acquired characters after birth, arising from the choice to walk in straightened posture more frequently due to the depletion of forest cover. In this Lamarckian perspective, a verticalized appendicular skeleton, or the permanent bipedality, did not have to show adaptation to arboricolism. Yet, a neonate Australopithecus was born with a small brain, an axial skeleton verticalized since the pituitary lodge, different from Homo genus (Dambricourt Malassé, 2004b) and a lower appendicular skeleton with large and short pelvis which imposed a permanent bipedality on the ground, but the upper appendicular skeleton, the hands and the feet were adapted to arboricolism. The genus Australopithecus differentiated in sub-species adapted to a range of environments between the forest-galleries, sparse woodlands and grasslands, thus, the link between the nervous system already verticalized at birth, the small brain (cerebral hemispheres), the forest depletion became less evident.

Where and when did Homo emerge? The scavenging activities by the use of lithic tools attest to animal feeds in the basic diet of the hominids (muscles, marrow, brain, grease) and the need for a supply of energy for more complex cerebral functional connectivity. The age of the oldest cut-marks on bones is, therefore, an indicator of this hominization process. The year 2015 has been rich in discoveries in this regard.

Concerning the intentional cut marks fossilized on a rib found at Dikika, Ethiopia, dating back to 3.4 Ma, it has been confirmed they were made with a sharp stone held by a hand (Thompson et al., 2015); concerning the oldest stone tools in Africa, the lithic assemblages from the Lomekwi 3 in West Turkana, Kenya, was found in situ and dated to 3.2 Ma (Harmand et al., 2015) and the oldest artefacts and cut marks in Asia at Longgupo in Central China are dated to 2.48 Ma (Han et al., 2015). Who were the hominids related to these elaborate activities?

The oldest fossils confidently assigned to Homo genus are two partial faces collected in the same geological conditions than Australopithecus and dated from more than 2 Ma. These specimens included the mandible of Uraha in Malawi (HCRP - UR 501, East Africa) which date to ca 2.4 Ma (Schrenk et al., 1993), and a maxillary from Afar (AL 266, Hadar, Ethiopia) which date to ca 2.3 Ma (Kimbel et al., 1997). A new hemimandible, Ledi-Geraru (LD 350-1 Afar, Ethiopia) dating from 2.8-2.75 Ma, was presented as the oldest fossil of Homo genus (Villmoare et al., 2015a). The authors agree on the australopithecine conformation of the mandibular symphysis, but assume however, a morphogenetic transitional species, half-human and half-australopithecine. The taxonomic value of the suspected human features has given rise to debate (Hawks et al., 2015 and Villmoare et al., 2015b). Finally, recent fossil hominids found in South Africa have been attributed to Homo naledi, nevertheless the geochronology is unknown (Berger et al., 2015). Since the dating is not established, in the current state of paleontological research, there is no consensus on the presence of Homo genus before the Plio-Pleistocene transition (2.588 Ma); the oldest specimen is located in the southern limit of the rift valley in Malawi. The authors of the cut-marks from Dikika and the artefacts of Lomekwi 3 could be species of Australopithecus or close relative (Kenyanthropus platyops), nevertheless, it is highly probable that remains of Homo genus exist somewhere since at least 3 Ma ago (Coppens, 2013).

The small number of fossils with cut marks must be replaced in a comparative context: at Java in South East Asia, only five bones to 30,000 fossils carried cut marks (Choi, 2003). In this regard, the small inlier of Masol was rather an exceptional site. The lack of tools on the slopes of the oldest and youngest geological layers devoid of fossils corresponded to what we would have expected if the collected artefacts and fossils were in the same layers before the current erosion. The study of the speed erosion and the observation of the lithostratigraphic condition of the collect, suggested that some artefacts were in the fossiliferous layers before erosion, especially since they did not match with Soanian or Hoabhinian-like assemblages, as demonstrated by Gaillard (Gaillard et al., 2016). The verisimilitude of lithic artefacts of late Pliocene age is strongly supported by the cut marks and the modeling of the erosion speed. The question could be solved by large excavations at Masol 1 and Masol 2. Concerning the absence of hominid fossils, it can be compared to that of rodents which left traces on several bones but are missing among the fossils. The chance to find remains of hominid is encouraged by the collect of rare carnivore and herbivore such as Panthera and Mericopotamus.

After 7 years of research devoted to geomorphology, the incision speed, lithostratigraphy, mineralogy, paleomagnetism and paleontology of the Quranwala zone, it is now possible to conclude that the cut marks on bones attest to the presence of hominins in the sub-Himalayan floodplain during the Late Pliocene. These hominines were familiar with an environment regularly exposed to monsoon and floods in the plain, where Himalayan rivers provided carrion for meat, grease, marrow and also raw material for the stone tools. Insofar as, on the ground, there is no hard stone other than the quartzite pebbles with a mean size of 15 cm, hominins likely used the direct percussion that gives an idea of their muscle power. The hominins of Masol had a good anatomical knowledge of the carrion as shown by the marks on the bones, which reveal organized, agile and precise gestures. The discovery of anthropic scavenging activity in Siwaliks dating from 2.6 Ma raises now the question of the geographic and phyletic origins of these hominines.

The identification of regions where Homo emerged is obviously constrained by the accessibility of the fossiliferous formations and the Afar Depression in Ethiopia is exceptional in this regard. The presence of apes in the late Miocene and lower Pliocene formations is also a criterion of first importance. The geographical paradigm has shifted, firstly, from South Asia to South Africa, then to East Africa and to Central Africa around the paleolake Chad since the discovery of Australopithecus barhelgazhali (3.5-3 Ma) (Brunet et al., 1995) and Sahelanthropus tchadensis (7 Ma) (Brunet et al., 2002).

In the context of the African paradigm, the presence of hominids in the Siwaliks leaves no other choice than their attribution to the Homo genus. Many questions will have to be solved. Now, it is necessary to postpone the emergence of the genus to a date that takes into account a large number of parameters, such as the time for a new species to reach a sufficient demographic size rather than to disappear (natural selection). The population must reach sufficient demographic size to extend beyond its reproduction area, yet Homo puberty is the most delayed among the primates and slowed down the frequency of births. It is necessary to evaluate the parameters that would have forced the populations to move until the shores of the Red Sea to the Upper Indus Basin over the generations for their supply of meat and marrow. The biological continuity between African and Eurasian bovid species is observed during late Miocene and then, but in early Pliocene, it decreases (Bibi, 2011).

The emergence of the Homo genus very likely dates back to earlier than 3 Ma. The oldest fossil whose appendicular skeleton is human-like is a distal humerus from Kanapoi in Kenya, dating from 4.2 Ma, assigned to Homo? (Senut, 1979). The appendicular skeleton of Kadanuumuu (KSD-VP-1/1, Ethiopia), dating from 3.58 Ma, resembled to human anatomy but the remains were assigned to Australopithecus afarensis (Haile-Selassie et al., 2010). This human-like anatomy reminds the hypothesis of Yves Coppens and Brigitte Senut about a Praeanthropus grade before Homo (Senut, 2003). In the African paradigm, the most probable cradle of Homo genus is the north of the Rift Valley, rather than Central and South Africa.

The first Asian paradigm is interesting. The comparison between the geographical distribution of fossil apes and the oldest human occupations including Riwat, shows clearly a superposition (Fig. 2). The partial mandible of Longgupo was first assigned to a descendant from Homo habilis, then, a dozen of years later, to a “mystery ape”. This revision arose from the paradigm of “Out of Africa” dating from 1.8 Ma; “such classifications are always open to interpretation. But I am now convinced that the Longgupo fossil and others like it do not represent a pre-erectus human, but rather one or more mystery apes indigenous to southeast Asia's Pleistocene primal forest. In contrast, H. erectus arrived in Asia about 1.6 million years ago.” (Ciochon, 2009).

With the new dating of Longgupo (2.48 Ma) and Masol (2.6 Ma), the mandible could be seen as a remain of the hominin expected at Masol. If this view is incorrect, then the oldest Pleistocene fossil hominins of South Asia are three massive molars collected at Longgudong cave, close to Longggupo, and assigned to a hypothetical Meganthropus (Dong, 2006 and Zhang et al., 2004) dating approximately from 2 Ma (Matuyama period, Hou and Zhao, 2010). Meganthropus is coherent with the expected anatomy of Masol hominins which have broken quartzite pebbles and used their sharp edges for their scavenging activities.

The extension area of Sivapithecidae towards the Indo-Gangetic plain can be evaluated thanks to the Potwar Plateau, which has not undergone the compression as in Himachal Pradesh, and all along the Himalayan range where the Mio-Pliocene layers are sometimes compressed up to the vertical. An important fossiliferous gap is observed in Indian foothills between the Upper Miocene in altitude (Himachal Pradesh) and the Late Pliocene in the Siwalik Frontal Range near the plain (Punjab), probably due to the very compressed geological layers. The fossiliferous deposits disappear, more than 5 million years of paleontological story are missing between the youngest Dhok Pathan assemblage (8 Ma) and the oldest Tatrot fauna (2.6 Ma) (Patnaik, 2013), that does not imply the extinction of Sivapithecus and Indopithecus during the lower Pliocene. The collect of fossils is considerably limited compared the Great Rift Valley; in Africa, the tectonics opens a book on the ape's evolution, whereas it closes this story in South Asia along the contact between the Indian and Asian plates, from the Hindu Kush foothills to the Indo-Sino-Myanmar ranges.

The ecological changes in the Himalayan floodplain during Late Miocene–Early Pliocene were studied by faunal assemblages, floras and analysis of tooth enamel (Patnaik et al., 2014) and they correspond to a fragmentation of tropical and sub-tropical forests with extension of grassland. These ecological changes in Africa are interpreted as the cause of the permanent bipedality, but in Asia, the same factors would have provoked the extinction. Nevertheless, the use of bipedal balance was well developed during the final Miocene in the Yunnan by Lufengpithecus from Shihuiba in South China, as shown by the femoral neck of PA 1276 (Xu and Liu, 2008). Finally, Grehan and Schwartz (2009) defend arguments for the Asian paradigm of Homo genus origins.

The emphasis on the locomotor apparatus of Australopithecus represents a major phase of the research into the evolutionary process of Homo genus. The co-existence of small brain, permanent bipedality and arboricolism was unexpected and the expected link with the increasing complexity of the nervous disappeared. This paradox was raised in the years 1980-1990 thanks to the distinction between the bipedality of the appendicular skeleton, and the verticality of the axial skeleton which surround the nervous system. Given the considerable implications of the Masol discovery in the current context of human paleontology and prehistory in Asia and Africa, it is necessary to recall the origins of the verticality. The straightening of the nervous system occurred in the amniotic liquid and at the scale of a few mm in relation with the phylogenetic increasing complexity of the neurogenesis and the cephalo-caudal control of the embryogenesis, 30 years of research have been recently synthesized (Dambricourt Malassé, 2011b). Since 1987, I remind in paleontology (Dambricourt Malassé, 1988) that the skull base is flat in all mammal embryos, aligned with the cephalo-caudal axis. Therefore, all embryos of fossil and extant species developed with a skull base aligned with the future vertebral column. All mammals keep this embryonic conformation after birth, except the Simians. At birth, the posterior base is more and more flexed from monkeys to modern Homo sapiens. The verticalisation of the skull base is an embryonic process due to neural tube kinetics (future nervous system). In its cephalic part, these kinetics induce spiral curvatures during the last week of the embryonic period which provoke the straightening of the base below the pituitary lodge (Dambricourt Malassé, 1988, Dambricourt Malassé, 1993, Dambricourt Malassé, 2006, Dambricourt Malassé, 2011a and Dambricourt Malassé, 2011b). Pongidae (Asia) and Panidae (Africa) share the same embryonic flexure at birth, less flexed than Homo sapiens, they exhibite shorter kinetics and a faster embryonic process. These kinetics are unchanged from their common ancestor, dating from at least 20 Ma. Only a prolongation of the embryonic cephalic kinetics common to the African and Asian apes can explain an increasing lowering of their embryonic skull base (Dambricourt Malassé, 1988, Dambricourt Malassé, 1993, Dambricourt Malassé, 2002, Dambricourt Malassé, 2004b, Dambricourt Malassé, 2005, Dambricourt Malassé, 2006, Dambricourt Malassé, 2009, Dambricourt Malassé and Deshayes, 1992, Dambricourt Malassé, 2010, Dambricourt Malassé, 2011a, Dambricourt Malassé, 2011b and Dambricourt Malassé et al., 2000), this evolution was saltationist all along the embryonic axis thanks to the homeotic genes (Dambricourt Malassé, 1993 and Dambricourt Malassé and Lallouet, 2009). The permanent bipedality is a post-natal consequence of the increasing complexity of the embryonic development, especially of the nervous system. Teilhard de Chardin was right in the great lines, this process started with the first monkeys 39 Ma ago, but acting with thresholds, or emergences, after millions years of stability. This discovery does not contradict radiation and speciation of a new morphogenetic pattern with adaptations of the appendicular skeleton to different ecological niches, and of the facial and dental growth to different diets.

Consequently, it is not surprising that the evolutionary threshold of neural verticality, especially of the cerebellum, was accompanied by the emergence of new concepts and new agility to create choppers or chopping tools (Dambricourt Malassé, 2011b). If Sahelanthropus tchadensis and its descendants could transmit such increasing complexity until a new embryonic threshold (Australopithecus), why Lufengpithecus lufengensis, for instance, already adapted to frequent bipedality in South Asia, could not transmit the same evolutionary properties? To conclude, the discovery of anthropic activities in the sub-Himalayan floodplain at the end of the Pliocene, should stimulate the research on the increasing complexity of the nervous system in close relation with the appendicular skeleton since the embryogeny, and its relationships with environmental changes at the planetary scale.