Chemical evolution hypothesis essay

The first two questions face anyone who cares to distinguish the real from the unreal and the true from the false. The third question faces anyone who makes any decisions at all, and even not deciding is itself a decision. Thus all persons practice philosophy whether they know it or not. Autocosmic Answers What is existing?

Chemical evolution hypothesis essay

Theories of bipedalism There are many theories that attempt to explain why humans are bipedal, but none is wholly satisfactory. Increased speed can be ruled out immediately because humans are not very fast runners. Because bipedalism leaves the hands Chemical evolution hypothesis essay, some scientists, including Darwinlinked it to tool use, especially tools for defense and hunting —i.

This theory is problematic in that the earliest stone artifacts date only to about 2. Twentieth-century theories proposed a wide array of other factors that might have driven the evolution of hominin bipedalism: Furthermore, if the early bipeds were regularly exposed to direct midday tropical sunlight, they would benefit from standing upright in two ways: Some scientists assume that the pre-bipedal primates were terrestrial quadrupeds, perhaps even knuckle-walkers like modern-day chimpanzees, bonobos, and gorillas.

Conversely, it is also possible that the first habitual walkers were already well prepared for terrestrial bipedality, having adaptations for running bipedally among branches and boughs, standing upright to forage overhead, and climbing vertical tree trunks and vines.

This scenario is suggested by studies of gibbons, which routinely engage in these arboreal activities and virtually never elect to move on the forest floor but, if forced to the ground, run bipedally.

Chemical evolution hypothesis essay

Gibbon s have relatively long, powerful lower limbs, the same number of lumbar vertebrae that humans have great apes have fewerand chests of humanoid configuration.

When walking on the ground, gibbons stand up straighter than chimpanzees, which are occasionally bipedal. Moreover, they exert less energy running on the ground than when running bipedally along branches or climbing vertically. Adopting a bipedal stance with full extension of the lower limbs thus would not have been a major challenge, since all apes have this capacity, though there would have been some alteration of the lower limb bones, joints, and ligaments.

The foot would probably have gone through the most dramatic change, from a prehensile organ to a heel-supported, propellent one. Increased size and frequent, sustained erect standing on extended lower limbs in order to forage overhanging branches in woodland, thicket, forest edge, and other relatively open habitats would favour the evolution of humanoid hip, knee, and foot structure.

While consuming their harvests, bipedal foragers may have squatted often, thereby further selecting for robust heels and for weight distribution between the heel and forefoot and between closely placed feet.

Frequent squatting and rising would enhance development of the hamstring, buttock, and anterior thigh muscles as hip and knee extensorswhich are vital for athletic bipedalism. Stretching upward would select for shorter toes and an arched foot.

Refinement of the terrestrial bipedal complex probably did not occur until hominins became less dependent upon trees for daytime refuge and other activities and began to forage widely afoot and perhaps to trek seasonally over long distances. Simply increasing body size would increase locomotor efficiencybecause larger animals can more effectively use the elastic energy of tendons and muscles, and they also take fewer strides to cover a given distance than a smaller animal would.

There is less size difference between the sexes in Homo species than in many other primates, largely because the females have become larger. Average size in male Australopithecus 41—51 kg [90— pounds] and Paranthropus 40—49 kg [88— pounds] is comparable to that of male chimpanzees 49 kg.

The size of females 30—33, 32—34, and 41 kg, respectively indicates that there was more difference between the sexes sexual dimorphism in these hominins than there is in chimpanzees.

Sexual dimorphism in H. Homo rudolfensis and H. This may have been the time also when the distinctive morphology of the human calf muscle triceps surae evolved. Unlike those of great apes, it is heavily tendinous, which facilitates its function as an energy-conservant spring during walking and running.

The unique epidermal and respiratory mechanisms of Homo sapiens may also have developed in conjunction with regular trekking, sprinting, and endurance running as ancestral Homo secured a foothold in open tropical and subtropical environments.

There is a rich concentration of sweat glands in our scalp apes have few or none in theirswhich helps to cool the head, especially the brain, in high temperatures and during vigorous activity. Postcranially, our abundantly vascular and highly sensitive sparsely haired skin is profusely endowed with sweat glands, whose copious secretions cool an extensive surface by evaporation.

The distribution of sweat glands is especially strategic for cooling us while running: Consequently, unlike hairy quadrupeds, we do not have to pause to pant in order to avoid overheating. Furthermore, unlike the chests of quadrupeds, those of humans are freed from the stresses of supporting body weight, necessarily coupled with exhalation in running quadrupeds.

Chemical evolution hypothesis essay

We can therefore alter our breathing patterns while moving at various speeds, thereby regulating energy expenditure. This species is classified by some paleoanthropologists as an African subgroup of H. The thorax of Neanderthal s H.Human evolution - The fossil evidence: By million years ago at least one hominin species, A.

afarensis, was an adept walker. In addition to anatomic evidence from this time, there is also a metre (foot) trackway produced by three individuals who walked at a leisurely pace on moist volcanic ash at Laetoli in northern Tanzania.

In all . Evolution unleashed Is evolutionary science due for a major overhaul – or is talk of ‘revolution’ misguided? Kevin Laland. Free Evolution papers, essays, and research papers.

Is evolutionary science due for a major overhaul – or is talk of ‘revolution’ misguided?

Primates and Evolution - What makes a primate a primate. A primate is defined by its many incredible features. Articles home page Creation vs. Evolution 0.

Introduction and table of contents The following is an organized presentation on the creation vs. evolution controversy. Abiogenesis, or informally the origin of life, is the natural process by which life arises from non-living matter, such as simple organic compounds.

The transition from non-living to living entities was not a single event, but a gradual process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis and cell membranes. Evolution is Not the Whole Story. s the bankruptcy of creation "science" becomes increasingly recognized, a new catch phrase, intelligent design, has been adopted by those who persist in their attempts to inject creationism into the science curriculum (see, for example, Of Pandas and People, Davis ; Matsumura and Cole .

Bruno Latour Tracks Down Gaia - Los Angeles Review of Books