Mankind is thought to have separated from a common ancestor shared with chimpanzees approximately 7 million years ago.1 At the time, among our ancestors was a group that decided to come down from the trees to live in the savanna as desertification of Africa's forests progressed. Although the term “ape-man” was used for early mankind who walked on two feet, improvements in the precision of dating methods and excavations from the latter half of the 20th century made it clear that many types of human species coexisted. Thus, the term “ape-man” is now only rarely used. Bipedalism was likely something attempted by many groups, and although many theories exist, the underlying reason for this transition is unclear.2 However, the advantages are clear – it enabled viewing vast distances and the use of hands to carry food, and ultimately led to the expansion of brain size. Interestingly, it took our ancestors an additional 4 million years to expand their brain size. This evolutionary delay might have been caused by climate changes in Africa. The progressively drying climate led to reductions in forestland, and our ancestors who lived on the plains were subjected to a new type of natural selection pressure, causing changes in their physique and behavior. One possible reason that orangutans remained in the trees when transported to Asia by continental drift was that although Africa and the Northern hemisphere began to dry and cool from approximately 30 million to 2.5 million years ago, Asia's forests in the tropical regions remained intact. Evidence of brain size expansion and the use of tools can be found from approximately 2.5 million years ago. Mankind at this stage is referred to as Homo habilis or Homo rudolfensis. The concept of pre-adaptation refers to gradually altering physique in advance so that it works to one's advantage once subjected to a particular environment. For instance, the advantages of walking erect are thought to have played an important role in the evolution of mankind much later; that is, approximately 2.5 million years later. The expansion of brain size also brought about a revolution in food energy, which accompanied the use of stone tools – the ability to ingest high caloric and nutritious meat products. Although they were “meat-eating” and hunted herbivorous animals on occasion, their meat supply likely came from food left over by carnivorous animals. In addition to increasing meat-eating efficiency, the expansion of brain size was accompanied by acquisition of modern man's physique, an expanded range of activity and loss of body hair. Although many human species remained in Africa, one group, the Peking man or Java man (also known as Homo erectus) moved to Eurasia approximately 1.8 million years ago in an event referred to as the first African exodus. At least one group of Homo erectus began using fire, a monumental event in mankind's history. Homo erectus existed until 250 000 years ago. We enter the age of modern man from approximately 200 000 years ago. The Neanderthals were another species of man that coexisted with modern humans during this period. This period saw the use of symbols, language and original art-forms. One group of modern humans left Africa approximately 100 000 years ago, and eventually adapted to all global environments in an event famously known as the second African exodus. Many terrains were conquered, including grasslands, deserts and mountains, and humans began living under various climates (tropical, temperate and polar). The conquering of various terrains is evidenced by the existence of Eskimos in polar regions, Bushmen in the deserts, Pygmies in the tropical rain forests, and Tibetan highlanders. The spreading of humans was particularly fast, with humans reaching Europe, Asia, North and South America, and Australia within the span of tens of thousands of years. Mankind at the time formed small nomadic groups and lived as hunter-gatherers. From a modest population of approximately 100 000 about 1 million years ago, the global population dramatically increased to 500 000 about 200 000 years ago, and further to approximately 10 million with the advent of agriculture about 10 000 years ago.3
48Les restes humains du Pliocène final et du début du Pléistocène inférieur de Dmanissi, Géorgie (1991–2000). I – Les crânes, D 2280, D 2282, D 2700
Les restes humains du Pliocène final et du début du Pléistocène inférieur de Dmanissi, Géorgie (1991–2000). I – Les crânes, D 2280, D 2282, D 2700
Read more72Megadontia, striae periodicity and patterns of enamel secretion in Plio‐Pleistocene fossil hominins
Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male-female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure.
Read more26Origin of the Genus Homo
The origin of the genus Homo in Africa signals the beginning of the shift from increasingly bipedal apes to primitive, large-brained, stone tool-making, meat-eaters that traveled far and wide. This early part of the human genus is represented by three species: Homo habilis, Homo rudolfensis, and Homo erectus. H. habilis is known for retaining primitive features that link it to australopiths and for being the first stone tool makers. Little is known about H. rudolfensis except that it had a relatively large brain and large teeth compared to H. habilis and that it overlapped in time and space with other early Homo. Our understanding of the paleobiology and evolution of the larger-brained H. erectus is enhanced due to its rich fossil record. H. erectus was the first obligate, fully committed biped, and with a body adapted for modern striding locomotion, it was also the first in the human lineage to disperse outside of Africa. The early members of the genus Homo are the first to tip the scale from the more apish side of our evolutionary history toward the more human one.
Read more2Bite force production and the origin of Homo.
The divergence of Homo from gracile australopiths has been described as a trend of decreasing dentognathic size and robusticity, precipitated by stone tool use and/or a shift to softer foods, including meat. Yet, mechanical evidence supporting this narrative is sparse, and isotopic and archaeological data have led to the suggestion that a shift away from a gracile australopith-like diet would not have occurred in the most basal members of Homo but rather only with the appearance of Homo erectus, implying that the origin of our genus is not rooted in dietary change. Here, we provide mechanical evidence that Homo habilis exhibits an australopith-like pattern of facial strain during biting but, unlike most australopiths, was not suited for a diet that required forceful processing by the molar teeth. Homo habilis was at elevated risk of distractive jaw joint forces during those bites, constraining muscle recruitment so as to avoid generating uncomfortable/dangerous levels of tension in the joint. Modern humans have similar limitations. This suggests that selection on skeletal traits favouring forceful postcanine processing was relaxed by the earliest stages in the evolution of our genus, implying that dietary or food processing changes played an important role in the emergence of Homo.
Read more3Living in Societies
![Figure][1] CREDIT: GETTY IMAGES An awareness of one's position and the relationships of others in a group is a rarity among vertebrate species, yet it has proved so spectacularly influential in just one species—our own—that it has become a major factor in determining the ecology of an entire planet. Although we can describe behavior patterns and speculate about their evolutionary advantage, we also need to understand their contribution to a species' reproductive success. A new wave of research is investigating the primate social brain within this evolutionary context, often through studies of wild primates. This special issue of Science explores the adaptive advantages of group life and the accompanying development of social skills. Science 's Greg Miller visited a chimpanzee sanctuary in Uganda to examine how researchers take advantage of these semiwild habitats to explore the cognitive abilities of our primate cousins (p. 1338). Just how valuable these opportunities can be is illustrated by the massive experimental study of physical and social cognition described by Herrmann et al. (p. [1360][2]). Silk (p. 1347) describes how research on sociality in baboons and other Old World monkeys is beginning to reveal the long-term relationship between social bonds and the fitness of individuals. In their book Baboon Metaphysics , reviewed by Jolly (p. 1326), Cheney and Seyfarth further illustrate the value of field studies. One of the most striking evolutionary trends among primates has been the expansion of brain size. Many competing theories have been invoked to explain this physiologically costly size shift. Dunbar and Shultz (p. 1344) review the evidence suggesting that it is the computational requirements of the special social lives of primates, in particular the requirement for pair bonding, that have driven the evolution of the human brain. An expanded capacity gives human beings unique cognitive skills, yet our primate cousins are quite capable of discriminating between necessary and superfluous actions, as described by Wood et al. (p. [1402][3]). Our brains give us extraordinary powers of imagination and sophisticated cultural adaptation; for instance, humans can undertake mental time travel and anticipate the consequences of actions. Gilbert and Wilson (p. [1351][4]) review the psychology and neuroscience of prospection; that is, how we predict future emotional experiences and how thinking about the future in the present can lead us astray. One of the most recent manifestations of our social brains has been the imaginative leap taken into the construction of virtual worlds. Our reporter Greg Miller undertook another field trip, this time to Second Life, and describes the progress researchers are making in using and understanding this new dimension of the human social experience (p. [1341][5]). It will be fascinating to learn how humans will cope with our increasingly virtual societies. We can only hope that our growing evolutionary insight into social behavior will help us to distinguish reasonable expectations of human society from those that are implausible. [1]: pending:yes [2]: /lookup/doi/10.1126/science.1146282 [3]: /lookup/doi/10.1126/science.1144663 [4]: /lookup/doi/10.1126/science.1144161 [5]: /lookup/doi/10.1126/science.317.5843.1341
Read more22On the possible use of fire by Homo erectus at Zhoukoudian, China
On the possible use of fire by Homo erectus at Zhoukoudian, China
3Exfoliative Dermatitis: Classification, Diagnosis and Treatment
Exfoliative Dermatitis: Classification, Diagnosis and Treatment
36Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa
Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.DOI:http://dx.doi.org/10.7554/eLife.09560.001
Read more19Deep History, Climate Change, and the Evolution of Human Culture
This Element follows the development of humans in constantly changing climates and environments from Homo erectus 1.9 million years ago, to fully modern humans who moved out of Africa to Europe and Asia 70,000 years ago. Biosemiotics reveals meaningful communication among coevolving members of the intricately connected life forms on this dynamic planet. Within this web hominins developed culture from bipedalism and meat-eating to the use of fire, stone tools, and clothing, allowing wide migrations and adaptations. Archaeology and ancient DNA analysis show how fully modern humans overlapped with Neanderthals and Denisovans before emerging as the sole survivors of the genus Homo 35,000 years ago. Their visions of the world appear in magnificent cave paintings and bone sculptures of animals, then more recently in written narratives like the Gilgamesh epic and Euripides' Bacchae whose images still haunt us with anxieties about human efforts to control the natural world.
Read more13The Evolution of Mammalian Brains from Early Mammals to Present-Day Primates
The changes in brains as they evolved from early mammals to modern humans involved a great expansion of overall brain size and especially neocortex. Early mammals were small, and their small brains had a proportionately small cap of neocortex divided into approximately 20 functionally distinct areas. Numbers of areas and the size of the cortical sheet increased with the first primates and contained 40–50 cortical areas. Overall the six million years of the evolution of modern humans from early bipedal apes, brains evolved from a great ape size of 400 cc to roughly 1400 cc, with neocortex having an estimated 200 cortical areas occupying 80% of the brain. This cortical mass of 16 billion neurons, together with a high level of hemispheric specialization, appears to be critically involved in mediating the impressive cognitive abilities of modern humans.
Read moreপ্রযুক্তির দর্শন ও ভবিষ্যতের মানুষ
Homo Neanderthal is no more a fiction story in 2023. The Nobel Prize winner in Medicine, Svante Paabo, has done the sequencing of the genome of the Neanderthal. Yuval Noah Harari has mentioned some other species of human existence alongside those of Homo Neanderthal, Homo erectus, Homo soloensis, Homo rudolfensis, and Homo ergaster. Homo sapiens is a wise man. It can be surmised from the research of the genetic engineers that the forefathers of Sapiens used technology. The hunters hunted by using technology. The agricultural civilization is completely dependent on technology. The first and second industrial revolutions made Sapiens dependent more on technology. If the fourth industrial revolution gets fully materialized, then not only humans will be dependent on technology but man’s usual ability to work will become dependent on technology to a great extent. The mystery of a wise man’s birth and death, that is, the rise and fall of the birth or death rate will be dependent on technology. Man has controlled the birth rate rapidly. Man will delay the process of death using technology in future. Biological Engineering and Cyborg Engineering are advancing fast. Now, connecting artificial intelligence with man’s usual intelligence is no longer a science fiction. Cyborg engineering is the combination of the organic and the non-organic. Though the age of technology is the age of man, the philosophy of technology is new in the domain of knowledge. The philosophy of technology gets its sway in the main stream philosophy of after the first and second World Wars. The German philosopher Ernst Christian Kapp (1808-1896) first used the two words “philosophy of technology”. The philosophy of technology is one of the branches of knowledge in the era of the Fourth Industrial Revolution.
Read more6The Spinal Cord in Hominin Evolution
Spinal cord dimensions increased in both relative and absolute terms during the course of hominin evolution. Recent discoveries demonstrate the presence of a fully developed human‐sized cervical spinal cord in Australopithecus afarensis at 3.6 million years before present (Ma) and in the cervical and thoracic regions of Homo erectus at 1.8 Ma. The fossil evidence suggests that these hominins possessed a fully human‐like postcranial neurological substrate for precision coordination of the arm and hand, corroborated by corresponding skeletal anatomy of the hand and shoulder, as well as discoveries of penecontemporaneous lithic use and putative throwing manuports in the archaeological record. These new fossils provide insight into the neurobiological underpinnings of sophisticated manual behaviours, and overturn prior thinking on the evolution of the central nervous system in the human lineage, indicating that the evolution of the hominin spinal cord was completed well in advance of advances in brain size. Key Concepts The brain and spinal cord are both larger in humans than those of the African great apes. New Australopithecus afarensis fossils from Woranso‐Mille, Ethiopia, demonstrate that hominin cervical spinal cord enlargement was completed by at least 3.6 million years ago. Evidence from Homo erectus now shows that hominin thoracic spinal cord enlargement was completed by at least 1.8 million years ago. These new discoveries reveal the neurological capability for fine‐motor coordination of the arm, hand, and thoracic muscles in our smaller brained ancestors. It is now apparent that spinal cord expansion was completed prior to brain size expansion in the human lineage.
Read more57Subnasal morphological variation in extant hominoids and fossil hominids
Subnasal morphological variation in extant hominoids and fossil hominids
நானும் நீயும் புலம்பெயர்ந்து வந்தவர்கள்!
Given that human species emerged through the process of evolution approximately more than 2.5 million years ago, various theories generally persist regarding the origin of humankind. Anthropologists and archaeologists state that the first human species originated in East Africa and subsequently spread throughout the world. Alternative theories suggest that human species may have originated and spread globally from regions like the Mediterranean, Asia, Europe, and China. Furthermore, theories also persist among us that the first human being may have originated in the lost continent of Kumari Kandam (Lemuria). However, based on the human fossil remains found globally to date—including the remnants of species such as Homo habilis, Homo erectus, Homo heidelbergensis, Homo neanderthalensis, and Homo sapiens, and the DNA molecules extracted from them—researchers analyze how these findings align with all present-day ethnic groups, including the Chakkiliyar community. The Chakkiliyar are identified as one of the most ancient indigenous communities, having lived approximately between 20,000 and 15,000 years ago. Furthermore, in India, the Chakkiliyar community is often referred to as Proto-Australoid, considered to be descended from ancient African and Australian lineages. The mtDNA haplogroups, or the specific branches of human ancestry, designated M¹ and M² are the genetic markers of those populations who migrated to South India. In this context, the ancestors of the Chakkiliyar are the direct descendants of Africa's ancient indigenous populations.
Read more1Forward from Taung
Forward from Taung
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