So far, the academic views on the origin of human beings are still not unified. After hundreds of years of research and debate, most scientists now agree that the African continent has undergone drastic crustal changes, forming a huge valley. The fault valley starts from Tanzania in the south, passes through the whole East Africa in the north, and reaches Palestine and the Dead Sea, with a length of 8 000 km. Great changes have taken place in the ecological environment on both sides of the broken valley, and the local forest apes gradually divided into two branches: the forest apes still living in the forest environment gradually evolved into modern apes; Due to the reduction of forests, forest apes living in the eastern highlands of fault valleys often have to come down from trees to find food. Due to the variation of body structure and the change of environment, the habit of walking with lower limbs has gradually formed, thus gaining great development opportunities in the long years to come. Until about 2 million years ago, there were ancient humans who walked upright and could make and use tools. Anthropologists call them Homo erectus. In a word, human beings originated from forest apes and generally appeared more than 4 million years ago. According to the discovery of early human fossils in Africa, it can be considered that human beings originated in Africa. In addition, some scientists' comparative study of human mitochondrial genes and genes on Y chromosome in different regions and African genes also supports the view that human beings originated in Africa and migrated to different regions of the earth.

In the past century, with the continuous discovery of new human fossils, the evidence about the origin of human beings has been increasing. Through the analysis and study of these fossils, people gradually understand the general outline of human beings from appearance to development into modern people. This long process can be roughly divided into the following four stages.

Basic stage

Go back to the present

Representative and main characteristics of fossil origin

Cultural development

Early ape-man

From 2 million years ago to 6.5438+0.75 million years ago, Homo habilis (Oduwe Gorge Valley, Tanzania) had a brain capacity of 637 ml and walked upright. His thumb and four other fingers can be clenched, but his movements are not accurate. Gravel can be made into a kitchen knife, and this stone culture is called Oduwe culture. Capable people live entirely by nature.

Late ape-man

1.75 million years ago to 200,000 ~ 300,000 years ago Yuanmou (Shangnabang Village, Yuanmou, Yunnan Province, China)

Beijingers (Zhoukoudian, Fangshan District, Beijing, China)

Javanese (West Java, Indonesia) has a brain capacity of 1 059 mL, can walk upright on two feet like modern people, and can build a variety of stone tools with flexible hands. Can make all kinds of stone tools, exquisite processing, stone culture has made great progress. It can live in groups of dozens of people with fire, and has certain ability to cope with natural changes.

Early homo sapiens

Maba people from 200,000 to 300,000 years ago (Maba Township, Qujiang County, Guangdong Province, China)

The brain capacity of Neanderthals (Neanderthal Valley, Germany) is 1 350 mL, which is close to that of modern people, and some primitive features (protruding mouth, developed eyebrows and ridges, etc.). ) is preserved in the constitution. Can make tools, can hunt large beasts, master artificial fire technology, and further improve the ability to conquer nature.

Late homo sapiens

Caveman from 50,000 years ago to/kloc-0,000 years ago (Zhoukoudian, Fangshan District, China)

The brain capacity of Kroma farmers (rural Kroma people) is basically the same as that of modern people, reaching 1 400 mL, and their posture is similar to that of modern people. Can make complex tools, such as stone tools, bones and horns, can make exquisite and unique works of art and decorations, can sew clothes, set up tents, and can carry out large-scale hunting activities. May start a matriarchal social life.

From the process of human evolution and development, it is not difficult to see that walking upright has changed the morphological structure of human beings; Labor has improved the living space of human beings; With the gradual improvement of labor level, the differentiation of brain structure and function is becoming more and more perfect; The appearance of language has brought essential changes to human development. These changes have continuously improved the level of human civilization. In the above process, human society has gradually developed.

The origin and development of mankind

2 Reasonable nutrition and food safety

Partial eclipse and picky eaters

Partial eclipse refers to the bad habit of eating only certain foods. For example, some people only like fish and meat and don't like vegetables. Being picky about food means eating only some foods you like and excluding other foods when eating. We know that the human body needs many kinds of nutrition, and no food can contain all the nutrients needed by the human body. Therefore, long-term partial eclipse, picky eaters, eating only one or several foods, will lead to the lack of certain nutrients in the body, unable to maintain health. In order to meet all kinds of nutrients needed by the human body, it is ideal to eat three meals a day on time, with reasonable animal and plant food collocation, diversified diet, no partial eclipse and no picky eaters.

gluttony

Some people eat too much or drink too much water, drinks and wine at once in a short time. Such overeating is harmful to health. This is because the food people eat, through the peristalsis of the stomach, forms chyme mixed with food and gastric acid, enters the small intestine, and is decomposed into absorbable small molecular substances under the action of bile, pancreatic juice and intestinal juice before being absorbed and utilized. However, the human body's digestive ability is limited. For example, an adult usually secretes about1500 ~ 2,500ml of gastric juice,1000 ~ 2,000ml of pancreatic juice, 800 ~1500 ~ 2,500ml of bile and1000 ~ 3,000ml of small intestine fluid every day. If you eat too much at a time, the supply of digestive juice will not meet the needs, which will cause gastrointestinal dysfunction, abnormal secretion of digestive glands and indigestion. Serious will cause acute gastroenteritis, acute pancreatitis, acute gastric distention, intestinal obstruction and other diseases. Excessive drinking will also stimulate inflammation of gastric mucosa, which will cause gastric bleeding or gastric perforation and endanger life for patients with gastric ulcer and duodenal ulcer. According to the data, excessive drinking will damage brain cells and germ cells. Therefore, primary and secondary school students in the growth and development period must develop good eating habits, pay attention to diet, and don't overeat.

Prevention of food poisoning

According to the content of the textbook, add some knowledge about puffer fish poisoning, poisonous mushroom poisoning and solanine poisoning.

Puffer is a kind of marine fish, which is caught in large quantities along the coast and in the lower reaches of the Yangtze River every spring. Fish contains toxins, especially in eggs, ovaries, skin and liver. The toxin of puffer fish is stable, which can't be destroyed by sun exposure, salting and general frying and cooking. Toxins act on nerve endings and nerve centers, paralyzing sensory nerves first, then motor nerves, and finally paralyzing respiratory centers and cardiovascular centers. Therefore, puffer fish is a highly toxic fish.

Mushrooms are a kind of fungi. Non-toxic mushrooms include Lentinus edodes and Tricholoma. Some mushrooms are poisonous, such as poison fly ointment, which can be poisoned if eaten by mistake. Vomiting, diarrhea and so on. It is light and life-threatening.

Solanum nigrum poisoning is caused by eating germinated and deteriorated potatoes. Potato tuber generally contains a small amount of solanine, which will not cause food poisoning. However, when stored improperly, potatoes will germinate and the color of potato skin will turn blue and purple. In these parts, the content of solanine is greatly increased. Eating this kind of potato will cause poisoning. For a few potatoes that germinate and the skin of the potatoes hardly changes color, these parts should be removed before cooking; Peeling, soaking or boiling thoroughly to remove soup can remove most of solanine; Soaking in water and adding vinegar to cook thoroughly can also destroy solanine.

food pollution

Food pollution can be divided into two categories: one is biological pollution; One is chemical pollution.

Biological pollution mainly refers to the pollution of pathogens. Bacteria, molds and parasite eggs will cause food pollution after infecting vegetables, meat and other foods. A fungus, Aspergillus flavus, can grow on damp and moldy food. Aspergillus flavus can produce a highly toxic substance-aflatoxin, which is a strong carcinogen, and its carcinogenicity is 4 000 times higher than that of benzo [a] pyrene. Mycotoxin pollution may be an important reason for the high incidence of liver cancer in some hot and humid areas of the world.

Chemical pollution refers to the pollution of harmful chemicals. The use of chemical pesticides in farmland and orchards is the main cause of chemical pollution of grain, vegetables and fruits. These pollutants can also enter the water body with rainwater, and then enter the fish and shrimp. After a lake in China was polluted by pesticides, many fish were deformed after cooking and had a strong medicinal taste, so they were called "medicinal fish". These "potion fish" have poisoned hundreds of people. Some farmers dry their grain on the road, which easily pollutes the grain by volatiles in asphalt, thus adversely affecting human health.

With the development of social urbanization, people get rid of the self-sufficient pastoral life. Many grains, vegetables, fruits and meat have to be transported or stored for a long distance, or processed many times before they can be sent to people. During the transportation, storage and processing of these foods, people often add various additives to the food, such as preservatives, fungicides, bleaches, antioxidants, sweeteners, flavoring agents, colorants and so on. And many of them have certain toxicity. For example, excessive use of preservative salicylic acid can lead to vomiting, diarrhea, paralysis of the central nervous system and even death.

Food pollution is a big problem that harms people's health. To prevent food pollution, not only individuals should pay attention to food hygiene, but also all departments of the whole society should make concerted efforts.

How to realize food safety in daily life

With the development of science and technology, the progress of human civilization and the deterioration of ecological environment, people are increasingly aware of the harm of various pollutants and pesticide residues to human health through the food chain. In this regard, some doctors suggested that in order to ensure family food safety, we should advocate the self-help law of food safety and health, specifically emphasizing the words clean, transparent, isolated, eliminated and confidential.

Clean vegetables bought from the market should be soaked for a period of time (generally 20 ~ 30 min) and then rinsed clean, so that some residual pesticides in vegetables can be removed. Among them, the soaking and washing time of fruits and vegetables and root vegetables can be less, while the soaking and washing time of leafy vegetables is longer. Vegetables that need peeling must be peeled. In addition, in order to reduce the loss of vitamins, vegetables should be washed first and then cut.

Food must be heated until it is cooked, that is, food must be cooked, and fresh and tender should not be pursued blindly. As long as the food is cooked, pathogenic bacteria, parasites and eggs in the food will die. Eat less raw seafood, not thoroughly washed meat and lettuce, and avoid eating pathogenic bacteria, parasites and eggs attached to them from entering the body.

When cooking separately, be sure to separate raw and cooked food. Use special knives and chopping boards when cutting cooked food, and clean them before use. The refrigerator is not a safe, so cooked food can't be kept for long. Tableware for patients and healthy people should be placed separately. The patient's tableware should be strictly disinfected. Toxic substances at home, such as pesticides and rodenticides, must be clearly marked and must not be mixed with food.

Sterilization is disinfection. Boiling water is the simplest and most economical disinfection method. Tableware can be cleaned to remove most microorganisms, and it will be better to cook for a few minutes.

Dense means sealed storage. Because some families now have heating and air conditioning, even in winter, the room temperature is generally above ten degrees Celsius. Therefore, due to the proliferation of bacteria, the exposed leftovers are easy to deteriorate. Therefore, the leftovers must be put into the refrigerator or cold place in time, and cannot be stored for too long.

Primary and secondary school students should pay more attention to food safety. To this end, experts from the Institute of Nutrition and Food Safety of China Center for Disease Control and Prevention require primary and secondary school students to do the following eight points:

1. Many drinks contain preservatives, flavors or artificial colors, and because of their high sugar content and high calories, drinking these drinks often is not good for the health of primary and secondary school students, so the best drink is boiled water.

2. Develop good hygiene habits, such as regular nail cutting and washing hands before and after meals. To prevent the spread of some infectious diseases and intestinal parasites.

3. Wash raw fruits and vegetables to avoid pesticide poisoning.

4. When choosing packaged food, we should pay attention to the production date and shelf life of the food.

5. Try to eat less leftovers. If you eat leftovers, you must heat them thoroughly to prevent bacterial food poisoning.

6. Don't eat raw food without hygiene guarantee, such as sashimi and raw water chestnut.

7. Don't eat food sold on the street without hygiene license.

8. Try to eat less fried, smoked and grilled foods, because these foods often contain more pollutants.

The emergence of green food

After World War II, developed countries such as Europe, America and Japan have successively realized agricultural modernization on the basis of industrial modernization. On the one hand, it has greatly enriched the food supply in these countries, on the other hand, there have been serious problems, that is, with the continuous input of agricultural chemicals into farmland, harmful chemicals are enriched in organisms through soil and water, and enter crops and livestock and poultry through the food chain, leading to food pollution and ultimately damaging human health. It can be seen that agriculture that relies too much on chemical fertilizers and pesticides (also known as "petroleum agriculture") will do harm to the environment, resources and human health, and this harm has the characteristics of concealment, accumulation and long-term.

1962, Ms. rachel carson of the United States took the measures taken in East Lansing, Michigan to eliminate beetles that hurt elm trees as an example, and disclosed various situations in which DDT caused harm to other organisms. The city sprayed many trees with DDT. Leaves fall to the ground in autumn, and insects eat them. After coming back in spring, robins ate worms, and almost all robins in the city died a week later. In Silent Spring, Ms Carson wrote: "Pesticides are widely polluted all over the world. Chemicals have invaded the water on which everything depends, infiltrated the soil and covered plants with a harmful film ... which has caused serious harm to human body. In addition, there is a terrible legacy that may not be detected within a few years, and may even have an impact on heredity, which will not be detected for generations. " Ms Carson's assertion undoubtedly sounded the alarm for the whole world.

In the early 1970s, the ideological trend of "organic agriculture", which spread from the United States to Europe and Japan and aimed at limiting the excessive import of chemicals to protect the ecological environment and improve food safety, affected many countries. Some countries began to adopt economic measures and legal means to encourage and support the development and production of pollution-free food in their own countries. Since the United Nations Conference on Environment and Development in Rio de Janeiro in 1992, many countries have started with agriculture and actively explored the sustainable development mode of agriculture to alleviate the serious pressure of petroleum agriculture on the environment and resources. Europe, America, Japan, Australia and other developed countries and some developing countries have accelerated the research on ecological agriculture. Under this international background, China decided to develop pollution-free, safe and high-quality nutritious food and named it "green food".

The emergence of green food in China has its inevitability: firstly, China is a country with a shortage of resources per capita. As a developing country, China must not take the old road of developing its economy at the expense of environment and resources. We must base economic and social development on the sustainable development of environment and resources, especially to establish and develop a mode of production to ensure the sustainable development of agriculture and food industry, and the development of green food can promote the establishment of this mode of production. Secondly, since the 1990s, the overall living standard of urban and rural people in China has started to transition from the level of adequate food and clothing to a well-off level, and the awareness of environmental protection and the demand for pollution-free food are getting higher and higher. Green food with pollution-free, safe, high-quality and nutritious connotation can just meet the needs of the transformation of living standards of urban and rural people. Third, with the in-depth development of reform and opening up, China's agricultural products and their processed products will inevitably enter the international market and participate in international competition. The introduction of green food is conducive to enhancing the competitiveness of China agricultural products and their processed products in the international market.

3 Air quality and health

There is a video below.

/czsw/jshzhx/shp zy/shp KL/200703/t 2007 03 22 _ 363372 . htm

The main cause of air pollution ":

1. Smoke from factories

2. A lot of harmful gases and dust emitted by automobiles.

3. Burning sulfur-containing fuel

4. Burning domestic garbage, leaves and waste plastics.

5. Burning industrial waste

smoke

7. Smoking in the kitchen while cooking.

8. The decay of garbage will release harmful gases.

9. Leakage of toxic gas from the factory

10. Indoor decoration materials slowly release toxic gases.

1 1. Road dust

12. spraying toxic pesticides on agriculture

13. Use products containing chemical diluents, such as hair gel.

14. harmful gases produced by photocopiers, televisions and other electrical appliances.

1. Sulfur oxides and nitrogen oxides are the main causes of acid rain, so it is necessary to adjust the energy structure and reduce the direct use of fossil fuels such as coal, oil and natural gas. The waste gas produced in industrial production can only be discharged into the atmosphere after purification.

2. The ozone layer is destroyed by gases such as chlorofluorocarbons and nitrogen oxides. Gases such as carbon dioxide, ozone, methane and chlorofluorocarbons will have a "greenhouse effect", which will warm the world and have a great impact on human normal life. In order to prevent the ozone layer from being destroyed and the "greenhouse effect" from being further aggravated, the following measures can be taken:

Save energy, reduce the use of fossil fuels such as coal, oil and natural gas, and make more use of clean energy such as solar energy, wind energy and geothermal energy. Restrict and gradually stop the production and use of HCFCs, vigorously plant trees, prohibit deforestation and protect wetlands.

3. The kitchen air contains gases such as carbon dioxide, carbon monoxide and sulfur dioxide released when fuel is burned, as well as gases and suspended matter (lampblack) generated when food is fried. Therefore, it is necessary to keep indoor air circulation and install a range hood in the kitchen. Newly built and renovated rooms will also contain a lot of harmful gases.

Smoking is harmful to health and pollutes the environment.