Residues or traces of plants or animals from earlier geological periods are called fossils. Studying such, one can see that a development, an evolution has occurred. Most fossils are found in sedimentary rocks, as sand or limestone, which formed in layers. But there are many more types of fossils. In ytligs layers, one finds young fossils, and the deeper you dig, the older findings do. By comparing fossils from different eras, one can study the development pipeline and specialization that sklett. When it comes to determining how old a fossil is, there are various methods. One can examine the so-called ledfossil available in deposit. Ledfossil plants or animals with typical features which Levet for a limited age over large parts of the earth. To get a more accurate age determination, you must measure fossilets content of certain radioactive isotopes. Isotopes decay at a known rate to stable substances.
Charles Darwin (1809-1882) was the first who gave an acceptable explanation for the evolution of species. During a circumnavigation in 1830, he collected biological matriel and made antckningar about their observations. Once back in England he worked and drew conclusions from its matriel. When in 1859 he published his book "The Origin of Species by Natural Selection", became a bestseller as thoroughly revised view on the origin of species and development. Darwin's theories were based on three facts:
1. All groups of organisms exhibit variation. 2. All organisms produce more offspring than survive to adulthood (only a fraction of cod females 85 million eggs survive to sexual maturity cods) 3. The development has had a long time in coming.
He drew two conclusions:
A) The environment benefits the most adapted, while poorly adapted to be eliminated or prevented from reproducing. B) The genes that favor survival and reproduction are passed on to the next genration.
If the environment and species showed no variation, nor would be no development. As we know, however, is changing the environment. In living organisms occurs occasionally change of capability due to radiation, viruses, toxins etc. Most of these changes are genetic factors unfavorable to the individual, since in many cases leads to serious defects that can be deadly. A change of environment may favor a new genes, and this will then be disseminated. For example björkmätarfjärilar. These are camouflaged and is barely on a normal birch trunk. But among birch gauges shall few percent completely dark color. These butterflies are easily detected by birds and get eaten. In England's coal district has, however, seen that this genetic predisposition leads to increased survival. The coal burning, nature has dark colored by the sotsom placed. Even the birch trunks are dark. Then it is natural colored birch meters are most easily detected while the dark survive. By the environment changes can thus an earlier harmful genes prove to be beneficial.
The atmosphere in which bygynnelsen surrounded our inanimate ground, missing oxygen (O2). Instead dominated various hydrocarbons with carbon dioxide, ammonia, hydrogen and water vapor. Since there was no oxygen, there was not the ozone layer, and therefore could solar-energy UV rays reaching the earth's surface. In the atmosphere lasted constant violent thunderstorms with blixtutladdningar. Radiation and lightning gave energy that could join gases into more complex compounds. The theory of how this atmosphere of life's morning, uratmosfären. could produce organic compounds, were tested for the first time in 1953. In a closed system subjected gases of ammonia, hydrogen, methane, and water for electric discharges. After a week had formed organic compounds, including amino acids, which are building blocks of our proteins. With different gas mixtures can also be formed organic bases as part of our genetic material, DNA and RNA. Unable broth in the primeval oceans rotten ?? No, for this to happen we need bacteria, and any such had not yet formed. But when microballoons had enclosed the genome that could copy itself and got metabolism, skädde an explosive development. Earth stench of rotten eggs when hydrogen sulfide released by the newly established bacterial fermentation processes. So småning if taken pigment out of the cells. There was then known as cyanobacteria. They could perform a simple photosynthesis, which led to a new gas mixed into the atmosphere - oxygen. When the air oxygen exposed to the sun's ultraviolet rays, formed treatomiga oxygen molecules, ozone. The atmosphere there arose an ozone layer, which filtered out the dangerous UV radiation. ThE AE essential for life forms to be staying on land. For some 1500 million years ago was an important specialization: DNA and proteins were collected in a nucleus inside a membrane. From the core of bearing cells development since higher plant and animal cells. Cellern could join together to multicellular organisms. Thereby, there was a specialization, which meant that some cells could manage nutrient intake, others procreation, dörsvar etc. During kambrium- and ordoviciumperioderna, for 600-440 million years ago, continued development of new species invertebrates. Worms, jellyfish, trilobites (crustaceans) and orthoceratites (Octopus with peel) dominates among djurfossilen. Towards the end of the period began the first vertebrates occur - the fishermen.
For more than 400 million years ago, the first plants to colonize the country. They lacked really roots. From a creeping rhizome could gaffelgrenade själkar extend a meter up. It was a completely new environment that the plants had to adapt to. Among other things, they must be able to protect themselves against dehydration, have tissues for fluid transport and supporting tissues that could keep them upright. In silurperiodens sea there were plenty of so-called armor cyclostomes, which are akin to modern-day chinless lamprey. During the Silurian also began the first fishes with real chaps occur. During the Devonian stripped the land masses of vascular cryptogams (ferns, fräken- and club mosses), which towards the end of the period formed the real ormbunksskogar. There was also the first insects, which, however, were wingless. Devon is the age of fishes. There were armored sharks, common sharks, lungfish and even some ray-finned species, that is the kind of fish that dominates today. In Devon Waters also performed the coelacanth fish, which had significance for the development. Of kvastfeningarna were three types: Tofssjärt-, Salamander and frog fish. All long considered to be extinct. 1938 scientists managed to catch a tassel tail and named it Latimeria, defter its discoverer Mrs. Latimer. Salamander The fishermen were the ancestors of newts (salamanders). Osteolepiformes raised frogs, toads and the urspruningliga reptiles. From these arose later, birds and mammals. An example of an animal that ventured onto land is Ichtyostega, the four-legged fish. It had sjärtfena but also gångben and lived probably in the shallow ponds. When these are sometimes dried out, the fish could move the country to other ponds, which still had water. Crawling Fish harde thus the ability to survive in water through that it could move across the country.
Homo sapiens, belong mammalian order of primates. Man has much in common with the great apes, approximately 98% of the genome, but differs in some crucial points upright walking, grasping hand with thumb holes, uninterrupted sex life, developed language (thanks to the larynx design), large brain capacity (with many "connections"). Monkeys and humans have been separated late. The first probable ancestor who himself was not a monkey, a species of the genus Australopithecus, appeared in East Africa for about 5 million. years ago. Early human species was Homo habilis, from about 2.3 million. years ago (the first who made tools) and Homo erectus about 1.7 million. years (which used the fire). They first appeared in East Africa, then spread across the Old World and gave rise to our own species, Homo sapiens of about 0.2 million. years ago. Although this was probably in Africa. The issue of the strongly built Neanderthals belonged to the species sapiens or constituted a separate species is controversial. She lived in the Mediterranean and s. Western and Central Europe during the last glaciation, but the jostling of about 40 000 years ago by the modern form of sapiens, popularly known cromagnon. He was a hunter and creator of cave paintings, and the anatomy is quite similar to people of our time.
Humans, monkeys and prosimians part of a group (order) of mammals known as primates or Mr animals. They had during its development mostly lived among the branches. This way of life has benefited properties grasping hands and stereoscopic vision. It has also led to a highly developed balance sine and good feeling in hands and feet. The requirement of fast reactions and needs to interpret sensory input and coordinate the movement has benefited individuals who had certain brain centers magnified. Such centers are cerebral cortex, whose development has led to the Primates high intlligens. Strepsirrhini had begun his adaptation to trädliv already during late kritperiod. At the beginning of the Tertiary period, ie 70 million years ago, was awarded the primates into different lineages. For 20 million years ago spread an ape, called Dryopithecus, across Africa, Europe and Asia. Various forms of Dryopithecus deemed to have given rise to the present-day humans and great apes (gorilla, chimpanzee and urangutang). Our ancestors and African apes continued to be a common group several million years. The group creature, man belongs, called hominids. Characteristic of these is upright again, the S-shaped spine, a short and bowl-shaped pelvis and gångben as longer than the arms. The time freed up the hands for new tasks. The thumb, which can be set against each other fingertip, touches gave a strong grasp of any tools. The motsättliga fingers also gave hominids opportunity to feel the seeds and other foods and thereby assess the quality. Man's family began with two genera known as Australopithecus (= sydapa) and Homo. Australopithecus lived in Africa's savannahs for about 1-4 million years ago. It was about a meter long and could use branches or the like as simple tools. From Australopithecus developed three or four species. Of the genus Homo evolved three species: H. habilis, H. erectus and H. sapiens. Homo habilis lived 2 million years ago in Africa alongside Australopithecus. Habilis does the handy, which refers to its ability to make stone tools. Homo habilis was thus the first senåldersmänniskan. Homo erectus, the upright transient, lived 0.3-1,6 million years ago. H. erectus could reach a length of 170 cm and henner brain was relatively large (1000 cm3). Increasing intlligens led to her could refine their tools and, not least, used the fire. She could build protection and probably also manufacture clothing. This allowed for H. erectus also spread to cooler regions.
For 50'000 years ago there were people in Europe that complies with today. To mark the final development stage researchers call this type of human Homo sapiens sapiens, or Cro Magnon Man for a bargain city in France. H. sapiens sapiens cranium has nackhål centrally located, so that the head balanced on the cervical spine. The ceiling is high and vaulted. The face is flat and vertically with utskutande POINT OF THE CHIN. The body is slimmer than neanderthalarnas, so it can not be a pure power as H. sapiens sapiens won the competition. Probably the most modern type of man the best at everything. Its tools, weapons, and hunting methods were more effective. Furthermore, the organizing efficient fireplaces, among others have found the remains of primitive oven. Boplattserna was better, and the findings of benn eels suggest a good technique for making clothing. In a short time spread H. sapiens sapiens to all continents. Northern Europe was covered remains of the ice sheet, and the oceans surface was therefore 150 m lower than today. With canoes or rafts, people could make several short trips across the narrow straits between islands to finally reach Australia. Road to America went over the country built that existed at the Bering Strait.
The development can be seen as two lines, one of which genrationen to the next and the next and so on. And the other one can see that the emergence of new species emerge constantly in his own little pace. In the first line, it can sometimes be changes involving mutation, a permanent change of arvsmassam. Most of the major fundamental changes are unfavorable and weeded out during the course of development. A few large and some small mutations can, however, be advantageous, especially when environmental changes. In most of them species that reproduce sexuelt, there are variations among individuals. Some animals are big some are small, higher metabolism smaller metabolism and so on. By the formation of large amounts of offspring, not enough nutrients to all. Many have time to die before it has succeeded propagated, it, mean that their genes are not passed on. If the genes increases an individual's chances of survival, it also increases the probability that the trait will be passed on to a new genration. Hereby is made that selection, a selection of the genes that are best adapted to the current situation. Darwin wrote about "The survival of the fittest", ie the most well-fitting survival. It has nothing singing with strength and "jungle" to do. For the individual concerned to acquire abundant offspring, who lives until it reaches sexual maturity, and thus to be able to spread their genes. The development has no set goals. In retrospect, however, point to different factors that knocking out certain genes, while others favored by selection. Many species differ only in one small detail, but the difference is many times more efficient that the intersections do not occur in nature. One example is the females of fireflies that recognize males of their own species on how they flash its Photophore. Experiments have shown that if a flashing pattern deviates only slightly from the normal for the species reacts females no longer on the signal. Different species of fireflies have flash patterns A sexual intimacy can be the source of fellowship and joy, a way to deepen relationships with each other. By kissing and kramr increases desire, and in the end you might want to "have" the other. But you may not feel ready to take the plunge and have intercourse. Yet one can make it good for each other through long-reaching sexual fondling, known as petting. Intercourse is indeed a joint document to both their satisfaction. Then comes the old saying: "It is more blessed to give than to receive." One should therefore take the time to waste with love and caresses. Through a proper foreplay becomes both parties ready and get a positive yield. During intercourse out man's penis back and forth in the sheath. By the glans sliding contact against the smooth vaginal wall escalate the man's feelings of pleasure. Similarly, the woman builds up a tension. When you reach höjdpungten of uploaded voluptuousness leading intercourse usually in an orgasm. This sexual ejaculation can take different forms, but afterwards will experience a relaxed pleasure. In connection with his orgasm gets the man ejaculation. There are various muscles that hugs vas deferens and urethra, so that 2-4 ml of semen pumped out in spurts. Hugging muscle contractions occur even when the woman's orgasm is much that needs to run smoothly, before a child can become. The pituitary gland produces a hormone that may oocytes to mature. Around the egg formed a fluid-filled bladder, follicle, which breaks at ovulation and oocyte becomes free. Oviduct funnel, which surrounds the ovary, captures the free oocyte. The emptied folliken converted to a corpus luteum, which delivers the hormone progesterone. This hormone helps to uterine mucosa is being prepared to receive a fertilized egg. In the fallopian tube, there are cilia, which transport the egg toward the uterus. For a befrukning to succeed, it must take place when the egg is in the fallopian tube. If the egg is fertilized, secure it at the uterine mucosa, and a placenta begins to form. From moderkakam emitted hormone that prevents both flre ovulating and rejection of the uterine lining (menstruation). The umbilical cord is headed fetal blood to the placenta. There occupies the blood nutrients and oxygen, while emitting waste products. Normally this happens, however, no mixing of maternal and fetal blood, but product change occurs through cell membranes in the contact area between the placenta and the uterine wall. After 24 weeks, the fetus is fully developed, and in the near månadern begins to call the new individual for a "child". In the run up to the birth child grows only in size. Towards the end of pregnancy in preparation woman's body on the upcoming birth. A hormone is controlled so that the cartilage Mellen blygdbenen softened. This allows the birth canal widens at birth. The hormone can also affect the disks (cartilage discs) between the spinal vertebrae, the back pain may occur. The woman feels increasingly contractions of the uterine muscles. While the child is förberätt before birth. Towards the end of pregnancy is the baby usually head down. The soft skull are not fused, but may försjutas slightly above the other. The child comes from a warm and comfortable environment in the womb, but are now out in the colder rumstempraturen. To cope with the heat balance, the child has developed a layer of so-called brown fat in the body. When the brown fat is broken down, generated a lot of heat, and you never see an infant with "goose bumps". At birth date cervix becomes soft and widen, allowing the child to pass. The muscles of the uterus makes regular, strong contractions. Pressure increases in the womb, and amniotic shortcomings in the end. The fluid the child has been at the then escape - they say that "water breaks" electricity in English "My water just broke". Uterine sharp contractions, contractions, coming towards the end of Enda one minute intervals. With the help of the abdominal muscles increases the pressure the woman, and child krystas out. Easier contractions This helps to expel the placenta. many first-time mothers are worried about the pain that can occur during labor. During pregnancy the cape can expectant mothers receive training isk psychoprophylaxis (prophylaxis = preventive action). The woman then learns among other things, a certain andningsteknink and become mentally stronger to cope with giving birth. In the maternity ward, the woman can additionally get analgesia with nitrous oxide, a local anesthetic into the cervix or pelvic floor, or so-called spinal anesthesia.
A menstrual cycle begins with a menstrual bleeding when the lining of the uterus is expelled. This is followed by a new mucosa is built up and ripen before the ejection. The cycle is repeated once a month in women of childbearing age. The menstrual cycle is governed by a part of the brain, pituitary, where the hormones are released. These hormones in turn affects the ovaries that produce the female sex hormone estrogen. Estrogen allows the lining of the uterus grows, that is, thickens and becomes richer in blood vessels. Around the middle of the menstrual cycle sends
pituitary hormone out signals that allow an egg detaches from the ovaries. The egg is picked up by the fallopian tube and transported to the uterus. After ovulation starts another hormone, progesterone, that are formed in the ovary. Progesterone with estrogen makes the uterine lining matures and prepares to receive and support a possible fertilized egg. If the egg is not fertilized ends progesterone production which in turn leads to rejection of the uterine mucosa. Menstruation has begun. It's bleeding from the many blood vessels in the lining. The bleeding - menstruation - ongoing until the lining to be formed, which usually takes from a few days up to a week. The amount of menstruation for a week is about 1 cup. One should keep themselves clean in the genital area, while in a menstrual period.
Adolescence means that the body changes both inside and outside. Surface is most noticeable on the boys. Eg voice, it gets darker, it's called ishing. The girls change is that they get the female form. Inside change it as much, for example. mood, to fall in love. When you become sexually mature happens many things in your body. It all starts with a small gland on the underside of the brain sends out hormones that start gonadal own hormone production. It's called getting into puberty. The sperm begins to mature in the boys' testicles and the girl then an egg to mature each month in the girl's ovaries, this is called menstruation. Hair begins to grow under the arms and on the genitals. It also begins to grow fast. The girls are often developed some years before. In puberty, it is very common to receive oily skin, blackheads and pimples, acne. Large fluctuations in mood. The boys grow mustaches and eventually beard. The larynx grows up, and you get a darker voice, called to come in ishing. At night when a boy asleep, it can happen that you get sädesuttömningar. This is known as pollution, and has relatively common. When the girls reach puberty, so get voting sore and grows, and the shape starts to become female. Your period will also then. Every month when the girls reach puberty at the woman becomes 50 years of age, she has menstruation. It does not take much hormones that the woman should get your period. Most women experience no further discomfort when menstruating, but some may get headaches, mood swings, or the like. Genitals, sexual organs, sexual organs, organs of plants and animals for the production of gametes, for mating, conception and fetal development. In humans consists man's inner genitals of the prostate, seminal vesicles and vas deferens, the exterior of the bag with the two testicles and penis. The woman's internal sex organs of both ovaries and fallopian tubes, uterus and vagina, the exterior of the labia and clitoris. The sperm are formed in the man's testicles, are stored in the epididymis, vas deferens passes through the seminal vesicles and prostate, where fluid and mucus are added. At ejaculation expelled through the urethra. The egg develops in the ovary, one each four week period, except during pregnancy. The egg carried by one of the fallopian tubes, where fertilization takes place possible. Non-fertilized eggs are shed at menstruation. Fetal development occurs in the uterus.
The penis of the man and the woman's clitoris is of a fetal origin. Pojkfostrer sex hormone gene transforms into a penis, flickfostrets to a clitoris
Under the heading sexually transmitted diseases - STD (Sexually Transmit Table Disease) usually collect a variety of skujdomar caused by bacteria, viruses, unicellular animals (protozoa) and insects. Spreading diseases associated with sexual contact and at other intimate body contact. Because the disease-causing organisms usually are well adapted to their environments, it is not always that a person experiences any symptoms. It is also common that a single person can suffer from multiple infections simultaneously.
In addition to the diseases that are set forth in the Communicable Diseases Act, see below, usually following diseases are counted to STD:
• Condyloma. • Genital herpes and the more unusual trikomonasinfektionen. • Although hepatitis A and B, and certain parasitic diseases can be transmitted sexually, particularly when intercourse between men.
Diseases Act The Act states that "With Communicable Diseases referred business to protect against infectious diseases are spread among people." So we have a law regulating the treatment and control of infectious diseases that can cause epidemics or uncontrollable spread of infection. Because the law is there to protect us humans gives the community the right to significantly curtail the personal freedom of an individual carrying an infection. The diseases are divided into social dangerous diseases and other infectious diseases. In this chapter, only a part of the community dangerous illness expect to be affected. In total there are 24 pieces societal dangerous diseases. In addition to the various "jaundice diseases" (hepatitis) and various STDs are most of these rare.
The venereal diseases that fall under the Communicable Diseases Act are:
• Gonorrhea. • Syphilis. • HIV infection. • Chlamydia. • Like the more unusual diseases ulcer molle and LVG (lymfgranuloma venereum).
A person who suspects that he / she is infected by one of these diseases is obliged to immediately seek a doctor and let the doctor do the investigations and take the necessary samples. It is also obliged to follow the directions given by the doctor informs. The victim must provide details of the person or persons that may have caused the infection and whether it may have been passed. All the examination, care and treatment that is required from infectious-protection point of view is free for the patient as well as the medicines needed. In support of the county medical work, he has the opportunity to enforcement action if an infected do not follow the given instructions. This may mean that the police's help retrieve a person who refuses to submit to testing. You can also force a person who continues to have sexual intercourse even though he / she is a vector, to isolation.
There are many different types of contraceptive agents. Being able to enjoy sexual intercourse without being afraid of being with children like most are obvious, and most often it is the case that one does not need to be the least worry if you for example use a condom throughout intercourse, all times, you do not get any sexual disease. The condom is the most common out-preventive agent, and provides a safety top 90 percent. It turns on the stiff penis before intercourse. Coitus interruptus is meant to take out the penis from the vagina before ejaculation. This can be difficult for some men, to cancel when it's most comfortable, some also difficult to know when the release will. However, if used in the right way at every intercourse, it provides a safety top 75 percent. Another way is for the woman to the pill regularly, it contains a spermicide.