April 17, ] [This essay is meant to be read in conjunction with "Chance from a Theistic Perspective" by Loren Haarsma. One of the more pernicious and persistent claims is Fred Hoyle's oft-quoted comment that accepting that evolution occurs by selection is like thinking that a would result if a hurricane went through a junkyard [Hoyle ].
Genetic data based on molecular clock estimates support a Late Miocene ancestry. Various Eurasian and African Miocene primates have been advocated as possible ancestors to the early hominins, which came on the scene during the Pliocene Epoch 5. Though there is no consensus among experts, the primates suggested include Kenyapithecus, Griphopithecus, DryopithecusGraecopithecus OuranopithecusSamburupithecus, Sahelanthropus, and Orrorin.
Kenyapithecus inhabited Kenya and Griphopithecus lived in central Europe and Turkey from about 16 to 14 mya. Dryopithecus is best known from western and central Europe, where it lived from 13 to possibly 8 mya.
Graecopithecus lived in northern and southern Greece about 9 mya, at roughly the same time as Samburupithecus in northern Kenya. Sahelanthropus inhabited Chad between 7 and 6 million years ago. Orrorin was from central Kenya 6 mya.
Among these, the most likely ancestor of great apes and humans may be either Kenyapithecus or Griphopithecus. Among evolutionary models that stress the Eurasian species, some consider Graecopithecus to be ancestral only to the human lineage, containing AustralopithecusParanthropus, and Homowhereas others entertain the possibility that Graecopithecus is close to the great-ape ancestry of Pan chimpanzees and bonobos and Gorilla as well.
In the former model, Dryopithecus is ancestral to Evolution of dogs essay and Gorilla. On the other hand, others would have Dryopithecus ancestral to Pan and Australopithecus on the way to Homo, with Graecopithecus ancestral to Gorilla.
This morphology-based model mirrors results of some molecular studies, which show chimpanzees, bonobos, and humans to be more closely related to one another than any of them is to gorillas; orangutans are more distantly related.
In a phylogenetic model that emphasizes African Miocene species, Samburupithecus is ancestral to Australopithecus, Paranthropus, and Orrorin, and Orrorin begets Australopithecus afarensis, which is ancestral to Homo.
The Miocene Epoch was characterized by major global climatic changes that led to more seasonal conditions with increasingly colder winters north of the Equator.
By the Late Miocene, in many regions inhabited by apelike primates, evergreen broad-leaved forests were replaced by open woodlands, shrublands, grasslands, and mosaic habitats, sometimes with denser-canopied forests bordering lakes, rivers, and streams.
Such diverse environments stimulated novel adaptations involving locomotion in many types of animals, including primates.
|Bitch: A History||Before the scientific era, people often made up imaginative stories to explain what they saw in the world. The scientific method changed that by requiring rigorous experimentation to test hypotheses and determine what is real.|
|Bitch: A History||A newborn English Setter puppy Photo courtesy Hannah Harris Natural selection is the process that Darwin proposed as the mechanism behind evolution.|
In addition, there were a larger variety and greater numbers of antelope, pigs, monkeys, giraffes, elephants, and other animals for adventurous hominins to scavenge and perhaps kill.
But large cats, dogs, and hyenas also flourished in the new environments; they not only would provide meat for scavenging hominins but also would compete with and probably prey upon them. In any case, our ancestors were not strictly or even heavily carnivorous.
Instead, a diet that relied on tough, abrasive vegetation, including seeds, stems, nuts, fruits, leaves, and tubers, is suggested by primate remains bearing large premolar and molar teeth with thick enamel. Behaviour and morphology associated with locomotion also responded to the shift from arboreal to terrestrial life.
The development of bipedalism enabled hominins to establish new niche s in forests, closed woodlands, open woodlands, and even more open areas over a span of at least 4.
Indeed, obligate terrestrial bipedalism that is, the ability and necessity of walking only on the lower limbs is the defining trait required for classification in the human tribe, Hominini.
Striding through the Pliocene The anatomy of bipedalism Bipedalism is not unique to humans, though our particular form of it is.
Whereas most other mammalian bipeds hop or waddle, we stride. Homo sapiens is the only mammal that is adapted exclusively to bipedal striding. Unlike most other mammalian orders, the primates have hind- limb -dominated locomotion.
Accordingly, human bipedalism is a natural development from the basic arboreal primate body plan, in which the hind limbs are used to move about and sitting upright is common during feeding and rest. Skeletal and muscular structures of a human leg left and a gorilla leg right.
The initial changes toward an upright posture were probably related more to standing, reaching, and squatting than to extended periods of walking and running.
Human beings stand with fully extended hip and knee joints, such that the thighbones are aligned with their respective leg bones to form continuous vertical columns.
To walk, one simply tilts forward slightly and then keeps up with the displaced centre of mass, which is located within the pelvis. The large muscle masses of the human lower limbs power our locomotion and enable a person to rise from squatting and sitting postures.
Body mass is transferred through the pelvis, thighs, and legs to the heels, balls of the feet, and toes. Remarkably little muscular effort is expended to stand in place. Indeed, our large buttock, anterior thigh, and calf muscles are virtually unused when we stand still.
Instead of muscular contraction, the human bipedal stance depends more on the way in which joints are constructed and on strategically located ligaments that hold the joints in position.
Fortunately for paleoanthropologists, some bones show dramatic signs of how a given hominin carried itself, and the adaptation to obligate terrestrial bipedalism led to notable anatomic differences between hominins and great apes. These differences are readily identified in fossils, particularly those of the pelvis and lower limbs.
Although we are bipedal, our pelvis is oriented like that of quadrupedal primates. The early bipedal hominins assumed erect trunk posture by bending the spine upward, particularly in the lower back lumbar region.
In order to transfer full upper-body mass to the lower limbs and to reposition muscles so that one could walk without assistance from the upper limbs and without wobbling from side to side, changes were required in the pelvis—particularly in the ilia the large, blade-shaped bones on either sidethe ischia protuberances on which body rests when sittingand the sacrum a wedge-shaped bone formed by the fusing of vertebrae.
Hominin hip bones have short ilia with large areas that articulate with a short, broad sacrum.The gene-centered view of evolution is a model for the evolution of social characteristics such as selfishness and altruism..
Acquired characteristics. The formulation of the central dogma of molecular biology was summarized by Maynard Smith. If the central dogma is true, and if it is also true that nucleic acids are the only means whereby information is transmitted between generations, this.
Lamarckism (or Lamarckian inheritance) is the hypothesis that an organism can pass on characteristics that it has acquired through use or disuse during its lifetime to its vetconnexx.com is also known as the inheritance of acquired characteristics or soft vetconnexx.com is inaccurately named after the French biologist Jean-Baptiste Lamarck (–), who incorporated the action of soft.
Human evolution, the process by which human beings developed on Earth from now-extinct vetconnexx.com zoologically, we humans are Homo sapiens, a culture-bearing, upright-walking species that lives on the ground and very likely first evolved in Africa about , years vetconnexx.com are now the only living members of what many zoologists refer to as the human tribe, Hominini, but there is .
This essay delves deeply into the origins of the Vietnam War, critiques U.S. justifications for intervention, examines the brutal conduct of the war, and discusses the . History and Evolution of Dogs Essay. Domestic dogs inherited complex behaviors from their wolf ancestors, being pack hunters with complex body language.
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