Someone explain the process of human evolution to me.......?

Question

I need specific details for example
focusing on the enviroment impact on our physical, techonologies, and cultural selfs...! HELP

I mean i dont beleive in evoltuion but its for my Anthropology class......so what can i do... =\

Answer 1

Okay, the environmental impact on evolution.

Evolution is a two-step process. First, an organism has to change. Each new generation of organisms is just a little bit different from its predecessors. This is because of mutation, which is when an alteration appears in the genetic code. Most mutations have no effect on an organism's body whatsoever, but the right mutation or combination of mutations can be the basis for an alteration to the organism's physiology or morphology.

The second level is natural selection and population. First, the mutated organism has to survive. If the mutation proves to be disadvantageous to the organism's survival in its environment, the organism has a higher chance of dying. If the mutation proves to be useful in a given environment, however, the organism's chances of survival will be higher. Once an organism has survived to reproductive age, it may produce a new generation of offspring. These offspring will share in their mutant parent's genetic code, and may carry even bear the same mutation. In this way, reproduction is key to evolution.

The other factor to keep in mind is that, given a relatively stable environment, most mutations, even beneficial ones, will tend to be bred out of a population. (Example: Take a bunch of dogs of all different breeds - chihuahuas, St. Bernards, beagles, whatever - have them mate, and have their offspring mate. After a few generations, the puppies will tend to look like plain brown or yellow dogs with narrow muzzles and stout bodies. This is because all the different dog breeds we have have been restricted from breeding with one another and exchanging genes.) So, in order for a mutation to really take root in a population of organisms, it must appear in a somewhat restricted population. In nature, something like a mountain range separating two populations of goats, or how an island will sometimes have miniature versions of continental animals.

In terms of evolution, technology and culture are parts of the environment. For instance, most humans in the world are lactose intolerant and can't drink a lot of milk. People who have descended from groups involved in with rearing cattle, however, tend to be lactose tolerant. Most Scandinavians and most Masai, for instance, are lactose tolerant because the societies in which they live in, or once lived in, were heavily dependent on cattle.

Answer 2

Simple:

We both want a banana. I figure out how to climb the tree. You don't, because you are lazy or stupid. I eat and have enough energy to go find an attractive member of the opposite sex and procreate. You don't because you are too hungry. My clever ambitious genes get passed on to my children. Your lazy stupid genes die with you when you get eaten by a hyena because you were too weak from hunger to run or fight.

End of story.

Answer 3

Humans have not evolved. If anything we are devolving. Genetic mutations are causing a deterioation in the quality of ours genes over the generations.

People were very smart in the past - building the pyramids etc.
An amazing ancient artifact was recently discovered, which is stunning in its complexity:

"The greater question puzzling scientists is how such a useful device could have disappeared entirely from the archeological record, so much so that no record of anything as complex appears for another 1,000 years.

London Science Museum's curator, Michael Wright states, ‘I find it as easy to believe that this technology survived unrecorded, as to believe that it was reinvented in so similar a form’.

http://www.creationontheweb.com/content/view/4815

Answer 4

For ease in typing, I will refer to all animals ancestral to humans as proto-humans or PH.

Until about 5 million years ago, the animal that would become a human and the animal that would become a chimpanzee were the same thing. At around 5 million years ago, the evolutionary line split (like twigs split from a large branch). This is because the proto-chimpanzee and PH were focusing on becoming successful in different environments. Proto-chimpanzees began to focus on arboreal (forested) environments, while PH began to inhabit grasslands and more open spaces. This change in the PH environment caused physical changes in the PH. Those PH with the best abilities to stand upright were less easy to kill on the grassland or savanna because they could see predators over the tall grasses. Also, the PH who could stand upright could carry things in his hands, which was another beneficial side effect that made the upright PH the most able to survive. Eventually, through natural selection, the PH that could stand upright became the PH that survived to bear children. Eventually, the PH stood more and more upright. By the time of Australopithecus afarensis about 4 milliohn years ago, PH were walking upright at least part of the time. This is evidenced in the upright footprints of an Australopithecine preserved in the mud in Laitoli Gorge, Tanzania (Africa).

Another physical change important in the evolution of modern humans was the gradual enlargement of the human brain. It appears that human physical form evolved before the human brain was fully evolved. However, it is thought that as other animals focused on physical strength as a survival tactic, humans, lacking in physical strength, focused on mental strength. Those animals most able to think to evade predators on the open savanna were those most likely to survive the predators. Therefore, the smartest animals were the ones who survived to have offspring, which were in turn smarter.

Techonological innovations in PH generally refer to advances in stone tool technologies. By at least 2.6 million years ago, PH had figured out how to form stone tools by bashing rocks together until one broke and created a sharp surface. Eventually, these stone tools got better so that there were standardized forms that PH passed on to their children.

Finally, an important cultural adaptation to the environment is the use of language. PH had no language, as we think of it. Anthropologists believe that language is a combination of a cultural development and a physical development, as certain structures in the brain had to appear as well as certain structures in the larynx (voice box) and also a cultural need. One theory is that language developed in order to coordinate hunting behavior. In any case, PH best able to communicate with each other were those who survived to pass on children.

As all of these adaptations occurred, the PH became more and more "human." It is thought that stone tools were first created by the PH "Homo erectus." This name might look familiar, because it has the first part of the human scientific name "Homo sapien." This means that it is in the same family as humans, making it closely related to us.

Anatomically modern humans (animals with skeletons that looked like ours, but possible didn't think like us or behave like us) finally evolved in Africa some time between 100,000 and 200,000 years ago.

Hope this helps.

Answer 5

how can you people say you dont believe in evolution when thousands of skulls of humans from hundreds of thousands of years ago are found yearly. Crazy christians.

Answer 6

How can you be sure you don't believe in what you don't understand? I don't think you'd respect the ideals of evolution because you dismiss it without trial.

Answer 7

Homini -> Australopithecines -> Humans and Proto-humans

Answer 8

Our planet earth had its origin about 4,500 to 5,000 million years ago (The universe is estimated to be 19,000 to 20,000 million years old and our galaxy 15,000 to 16,000 million years. The origin of sun may date back to 5,000 to 6,000 million years). Life originated on earth nearly 2,000 to 3,000 million years ago. It is believed to have taken 1,500 to 2,500 million years for the earth to cool down and to account for the formation of simple protein molecules from inert gases and the transformation of these protein particles into tiny living organisms. From these single celled organisms, more complex and multi cellular organisms came into existence due to the process of mutation and selection. The first backboned animals evolved were the fish, from whom diverged amphibians and later on the reptiles. Mammals differentiated themselves around 180 million years ago. Man belongs to the order of mammals called primates, which are about 70 million years old. The evolution of man from our nearest relatives among primates, the chimpanzees, may date back to 20 to 25 million years. The most primitive man (Homo habilis) appeared on the face of earth three million years ago and Homo sapiens owns a history of one lakh years. It was some 40,000 years back that modern man (Homo sapiens sapiens) came into existence.

Scientific researches conclude that the synthesis of first genetic material has been preceded by a chemical evolution that accomplished itself some 4 billion years ago. The first step constituted the production of amino acids, organic bases and simple sugars. This was closely accompanied by the manufacturing of polypeptides. The gaseous envelop of the earth was then so rich in methane, carbon monoxide, ammonia and hydrogen while water was plenty in the atmosphere. On the contrary free oxygen and carbon dioxide seem to have been scanty in availability. A wide range of stimulants comprising sunlight. X-rays, cosmic rays, lightening and volcanic heat were quick to spur chemical reactions. Scientific probing points out that the first molecules generated must have been formaldehyde, hydrogen cyanide and cyanoacetylene. In the presence of water and ammonia, these condensed and a manifold production of compounds was the corollary. It is quite apparent that primitive earth could freely and spontaneously synthesize, all the components of nucleic acids like sugars, amino acids, adenine, pyrimidines and phosphoric acid.

Between the origin of life and the evolution of man, there lies a slow process of evolution and progress. Innumerable varieties of plants and animals take their positions in the ladder of evolution falling over a span of 2,000 to 3,000 million years. True, many species of those animals and plants are no more and go under the title of the extinct. Still our planet possesses a really wide spectrum of plants and animals comprising an astonishing number of more than two million species.

The units of heredity are `genes’ located on chromosomes. There are 46 chromosomes in 23 pairs in human cell. Deoxyribonucleic acid (DNA) is the deciding factor which constitutes `gene’. The two or more forms of genes that are responsible for alternate traits (e.g. Tall and Dwarf) are the `alleles’. Individuals in whom the two alleles of a given pair are the same (TT or tt) are termed homozygotes. In heterozygotes the two alleles of a given pair are different (Tt).

‘Phenotype’ refers to what an individual looks like. Genotype describes the individual’s genetic constitution. In a tall phenotype the genotype can be `TT’ or `Tt’ when tallness is dominant. In case the trait is not dominant, the heterozygote will be intermediate between the parents.

Every gene is entrusted with one primary function which is to be responsible for a particular trait. The number of genes in a human cell is estimated to be around thirty thousand.

Man possess approximately 1014 cells, all developed from the single cell called zygote or fertilized egg. Zygote is the fusion product of male and female gametes(sperm and egg). Gametes have only half the number of chromosomes and hence the zygote obtains equal number of paternal and maternal chromosomes. A fertilized human egg (the human egg is a spherical cell of 0.14 mm diameter and weighs 0.0015 mg. The size of sperm is much more smaller) carries all adequate hereditary material to direct its development through the different stages of growth from embryo up to old age.

Mutation is a heritable change occurring in the genetic material. These arise within DNA molecules. Mutations usually occur at random and are quite accidental. Alterations in DNA molecules form the basic cause for all differences between living organisms. Mutation encountered for any particular human gene happens to be one out of every 1,00,000 sex cells of either sexes. That is, in general 2 to 20 per cent of all sperms or eggs carry at least one new mutation and thus about 11.1 million mutations occur per generation in the US. Joshua Lederberg (Nobel laureate for his work on bacterial genetics) estimated that environmental factors – drugs, food additives, unclean air, and the like – might well account for eighty percent of the prevailing human mutation rate.

Except in very rare cases, mutations are harmful. But the occasional beneficial ones are indispensable for the evolutionary process. (Evolution is a change in the genetic makeup of a population). Most of the pernicious mutations are eliminated during the process of natural selection whereas the
advantageous ones are transmitted to the future generation. Natural selection is the result of favourable variation in a population. Individuals endowed with the favourable variation will inevitably have an advantage over others and a greater percentage of such individuals survive and create off springs. Gradually the frequency of this variation increases. In the long run, the desirable variation which was rare on its first appearance will turn to be a trait by which a population is specially marked. Eventually contrasts between populations isolated ecologically or geographically ever widen due to continuous mutations and selection process so that mating is no longer possible between them and are apt to be christened separately. Thus new species are formed over years and very randomly.

Evolutionary changes can be seen in all living organisms, leading first to the formation of sub-groups within the species and then to the formation of species with reproductive isolation.

The sub-groups in man are known as races. However, human beings are the only species which has intentionally misused racial differences for violence. Today, the leveling up of geographical barriers due to advanced and speedy transportation methods has paved the way for increased interbreeding between races.

An advantageous trait need not endow the mutant individual with outstanding strength or intelligence. It merely enables the mutant to survive better in its environment and makes it more fit to reproduce.

Natural selection need not necessarily involve combats between individuals in a group. It simply favours those variations useful at a particular time, regardless of their eventual value. A species perfectly adapted at present may be doomed for want of hereditary variability by a change in the environment. Hence preservation of a living species depends on the concealed genetic variability it possesses.

Crossing-over also helps the genetic variability that forms the raw material for evolution. Crossing-over (the exchange of sections between chromosomes of a given pair is known as crossing-over) begets a variety of gene combinations, both in eggs and in sperms.