What are population pyramids?, Schemes and Mind Maps of Evolutionary biology

Download What are population pyramids? and more Schemes and Mind Maps Evolutionary biology in PDF only on Docsity! Page 1 What are population pyramids? They are bar charts which show the structure of the population by sex and age at a given moment. The vertical axis represents the age groups in five-year bands. 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Page 2The horizontal axis shows the population numbers in percentages or in absolute figures: 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Percentage of total population Page 5 The shapes of the pyramids The shape of the pyramid reflects the population type. We can distinguish a triangular shape, which reflects a young population type; a bell shape, which represents an adult population type; and an urn shape, which indicates an ageing population. Percentage of total population Men 4 620 593 people Women Men Women 1.22% 1,65% 22.64% 27,00% 24.03% Elderly Adults Young people 23,46% 5 028 362 people 2 1345678910 00 1 2 3 4 5 6 7 8 10 Source: International Data Base, U.S. Census Bureau. Total population in 2006: 9,648,955 people Chad Triangular Men Women 5.69% 7,63% 34.69% 34,35% 9.04% Elderly Adults Young people 8,61% 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Percentage of total population Men 16 358 271 people Women 16 740 661 people 2 1345678910 00 1 2 3 4 5 6 7 8 9 Total population in 2006: 33,098,932 people Canada Urn Source: International Data Base, U.S. Census Bureau. Men Women 4.36% 6,27% 32.07% 32,06% 12.91% Elderly Adults Young people 12,33% 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Percentage of total population Men 19 697 658 people Women 20 224 175 people 2 1345678910 00 1 2 3 4 5 6 7 8 9 10 Total population in 2006: 39,921,833 people Argentina Bell Source: International Data Base, U.S. Census Bureau. Page 6The triangular pyramid is representative of a young population. Its base is wide, due to the high birth rates. The percentage of young people exceeds 35%. The population rapidly falls towards the top, due to a low or medium life expectancy, so there are relatively few elderly people: less than 5% of the population. This pyramid, which characterised all countries in the first demographic phase, is now typical of the most underdeveloped countries of Africa and Asia. Percentage of total population Men 4 620 593 people Women Men Women 1.22% 1,65% 22.64% 27,00% 24.03% Elderly Adults Young people 23,46% 5 028 362 people 2 1345678910 00 1 2 3 4 5 6 7 8 10 Source: International Data Base, U.S. Census Bureau. Total population in 2006: 9,648,955 people Chad Triangular Page 7The bell-shaped pyramid indicates an adult population. Its base is moderate, as birth control has begun. The percentage of young people is between 25% and 35%. The population falls slowly towards the top, due to a high life expectancy, so the percentage of elderly people is moderate: between 5% and 12%. Today, this pyramid is typical of developing countries in Central and South America, Asia and the Middle East. Men Women 4.36% 6,27% 32.07% 32,06% 12.91% Elderly Adults Young people 12,33% 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Percentage of total population Men 19 697 658 people Women 20 224 175 people 2 1345678910 00 1 2 3 4 5 6 7 8 9 10 Total population in 2006: 39,921,833 people Argentina Bell Source: International Data Base, U.S. Census Bureau.