Species and Populations PDF

Species A species refers to a group of individuals of the same type that are capable of interbreeding and producing fertile offspring under natural conditions. Naming Species Each species has a scientific name that is made up of two parts, referred to as binomial nomenclature. The name is treated...

Species A species refers to a group of individuals of the same type that are capable of interbreeding and producing fertile offspring under natural conditions. Naming Species Each species has a scientific name that is made up of two parts, referred to as binomial nomenclature. The name is treated grammatically as if it were a phrase in Latin and is always in italics if typed or underlined if handwritten. Also, the first name always starts with a capital letter and the second one starts with a small letter. Common Name Scientific Name Human Homo sapiens House Cat Felis domesticus Chimpanzee Pan troglodytes Olive Tree Olea europea Species that are most closely related to each other might have the same first part of the name. The last part of the name, however, is always unique. r re ge Z En This naming system was devised by Carolus Linnaeus. Any new species that is discovered must be named in Latin (or in Latinized form) by the person or team who discovers it. The name is usually chosen based on a distinct feature, location, or an aspect of its biology but this is not always the case. In some cases, species are also named in honour of someone (discoverers cannot name the species after themselves). Scientific names are accepted by scientists all across the world and are important since they can be used to communicate the same species without difficulty due to language and can also sometimes avoid misconceptions about certain species. Hybrids If different species succeed in interbreeding and produce offspring, this offspring is called a hybrid. Hybrids are usually sterile: they have an odd number of chromosomes and cannot produce any sex cells. Without any sex cells, no subsequent offspring can be produced. Although rare in nature, hybridisation may occur in regions where two closely related species cohabitate. POPULATIONS | 1 Biological Populations A population refers to all the organisms of the same species that live in a specific area, at a given time, and can interbreed to produce fertile offspring. Population Size Population size refers to the total number of individuals of a species within a specific geographic area at a particular point in time. Four main factors affect population size: Births: Births refer to the process of new individuals being born into a population. This includes offspring that are produced through reproduction, such as live births or hatching from eggs. Births contribute to the increase of the population size. Deaths: Deaths refer to the process of individuals dying within a population. Deaths can occur due to various factors, including natural causes, predation, disease, accidents, or other environmental factors. Deaths contribute to the reduction of the population size. Immigration: Immigration is the movement of individuals into a specific population r re ge Z En from other areas or populations. When individuals from outside sources join a population, they add to the population size. Immigration can be influenced by factors like resource availability, habitat quality, or the search for mates. Emigration: Emigration is the movement of individuals out of a specific population to other areas or populations. When individuals leave a population, they reduce the population size. Emigration can be influenced by factors like competition, predation, resource scarcity, or changes in habitat conditions. Population Density Population density is a measure of the number of individuals of a species within a specific area or volume. It quantifies the level of crowdedness of a population in a given space. Population density is usually expressed as the number of individuals per unit area or volume. Population density is calculated as follows: 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐃𝐞𝐧𝐬𝐢𝐭𝐲 = 𝐀𝐫𝐞𝐚 𝐈𝐧𝐡𝐚𝐛𝐢𝐭𝐞𝐝 𝐛𝐲 𝐭𝐡𝐞 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 POPULATIONS | 2 Population Growth Biological population growth refers to the increase in the number of individuals of a particular species in a specific area over a period of time. Population growth is a fundamental aspect of ecology and plays a crucial role in shaping ecosystems, understanding species dynamics, and managing natural resources. Biotic Potential The biotic potential, also known as intrinsic rate of natural increase, refers to the maximum rate at which a population of a particular species can grow under ideal conditions, without any limiting factors. Therefore, the biotic potential represents the inherent capacity of a species to reproduce and increase in numbers. Biotic potential is determined by a number of factors: Reproductive Output (Litter Size) Species that produce many offspring tend to have a higher biotic potential. Reproductive Frequency r re ge Z En Species that have multiple reproductive events in a year have a higher biotic potential. Age at Reproductive Maturity Species that reach reproductive maturity at a younger age usually have a higher biotic potential since they have the potential to produce more offspring over their lifetime. Survivorship Species with higher survivorship of offspring have more opportunities to contribute to population growth. Lifespan Species with longer lifespans have more opportunities to reproduce and contribute to population growth. If the biotic potential is fully expressed, growth would be unrestricted and population sizes would grow indefinitely. However, full expression of the biotic potential of an organism is very unlikely since it is severely restricted by various limiting factors. POPULATIONS | 3 Environmental Resistance Environmental resistance refers to the factors or conditions in the environment that limit or constrain the growth of a population. It acts as a counterbalance to the biotic potential by preventing populations from growing indefinitely. Two types of limiting factors constitute environmental resistance: Density Dependent Factors These factors are influenced by population density and become more significant as the population density increases. Density dependent factors are usually biological (biotic). Examples include competition for resources, predation, disease, parasitism and territorial behaviour. Density Independent Factors These factors are not influenced by population density and limit population growth regardless of population density. Density independent factors are usually physical (abiotic). Examples include natural disasters, extreme weather, climate change, fire, habitat destruction and pollution. When the population of a species is small, the environmental resistance is usually low: there r re ge Z En are many resources available, and the population can keep growing quickly. As the population grows, environmental resistance also increases since resources become limited and competition increases. Carrying Capacity The carrying capacity refers to the maximum number of individuals of a species that a specific ecosystem or habitat can support over a sustained period of time. It represents the point at which the available resources and environmental conditions are in balance with the population's needs, resulting in a stable population size. The carrying capacity is usually determined by the interactions between the biotic potential and the environmental resistance. When a population is below the carrying capacity, resources are relatively abundant, and individuals can access what they need without significant competition. Under these conditions, the population can grow and expand. However, as the population approaches the carrying capacity, resource availability becomes limited. This scarcity may lead to increased competition for resources, reduced reproductive success, increased stress, and higher mortality rates. These factors regulate population growth and maintain it around the carrying capacity. POPULATIONS | 4 Population Growth Models Exponential Growth Exponential population growth refers to a rapid and continuous increase in the size of a population over time. With such growth, a population increases at an accelerating rate over time - in the early stages, the population grows slowly, but as time progresses, the growth rate becomes increasingly rapid. It is characterized by a J-shaped curve on a population-time graph. r re ge Z En Exponential growth assumes unlimited resources and the absence of any limiting factors such as predators and disease. This type of growth is common in populations with abundant resources and favourable environmental conditions, such as introduced species in new environments or rebounding populations after a decline. If exponential growth goes on indefinitely, the biotic potential will be reached. However, this is highly unlikely as environmental resistance will slow down growth and force populations to stabilize near the carrying capacity of the area. Stabilization of population growth will lead to sigmoid or irruptive growth. POPULATIONS | 5 Sigmoid Growth Sigmoid population growth begins exponentially and then slows down as a result of environmental resistance until it stabilises at the carrying capacity of the area. This type of growth is seen in any stable populations occupying a fixed geographic space. The resulting population-time curve is sigmoidal (S-shaped) and tends to stabilise at the carrying capacity (k). Lag Phase: Population growth is slow due to a shortage of reproducing individuals that are widely dispersed. r re ge Z En Log (or Exponential) Phase: Population growth is exponential since resources are abundant and environmental resistance is low: natality greatly exceeds mortality. Transitional Phase: Population growth starts to slow as environmental resistance begins to limit growth – resources begin to deplete and competition for survival begins: natality starts to fall, and mortality begins to rise. Stationary Phase: Population growth stabilizes at the carrying capacity as the biotic potential is in balance with environmental resistance: natality and mortality are approximately equal, and growth becomes static. Species showing sigmoid growth are described as k-strategists. The strategy is to grow slowly and adapt well to the environment, living with populations close to the carrying capacity of their habitat. Several characteristics are common in k-selected species, such as: Long lifespan Mature slowly Large body size Produce few offspring High parental care High survival rates of offspring POPULATIONS | 6 Irruptive Growth Irruptive growth is associated with species that have irregular population outbreaks and is characterized by populations that experience occasional, rapid increases followed by sharp declines. Species exhibiting irruptive growth are described as having a boom-and-bust lifecycle that fluctuates above and below the carrying capacity of an area. Irruptive population growth begins exponentially and increases until it eventually overshoots the carrying capacity of the area. Following an overshoot, the population normally falls (dieback) since there are limited resources and space. As population numbers fall, this will allow the natural environment to recover. The resulting population-time curve is characterised by overshoots and diebacks around the carrying capacity. re r ge Z En Irruptive growth is highly influenced by fluctuating environmental conditions, such as periodic availability of abundant resources or favourable climatic events. These conditions can trigger sudden population explosions, but once the resources are depleted or conditions change, the population crashes back to lower levels. Species showing sigmoid growth are described as r-strategists. The strategy is to flood the habitat with offspring so that at least some of the offspring will survive to reach reproductive age. Several characteristics are common in r-selected species, such as … Short lifespan Mature quickly Small body size Produce many offspring Little to no parental care Low survival rates of offspring POPULATIONS | 7 Population Crashes A population crash refers to a sudden and dramatic decline in the size of a population over a short period. Causes of population crashes can include: Overconsumption of Resources If a population grows too quickly, it may overshoot the carrying capacity by a large amount. When this happens, resources may be depleted to such an extent that the habitat is not able to sustain the population any longer, leading to a population crash. Disease Rapid spread of disease in densely populated areas can lead to widespread mortality. r re ge Z En Natural Disasters Events such as hurricanes, floods, volcanic eruptions, wildfires and tsunamis can wipe out large portions of populations in affected areas. Habitat Destruction Rapid habitat loss due to human activities, such as deforestation, urbanization, and agriculture can lead to population crashes. Overexploitation Overfishing, overhunting, and overlogging can decimate populations of targeted species. POPULATIONS | 8 Human Populations Demography refers to the statistical study of human populations. It examines the size, structure, and movements of populations over space and time. Collecting Demographic Data Census A census is a form of national stocktaking. It is one of the oldest and most reliable sources of information about the count, characteristics, composition and condition of a population. It aims to provide a comprehensive and accurate snapshot of a country's population at a specific point in time. A census is usually taken every 10 years and participation in the census is usually obligatory by law. This means that all residents, whether citizens or non-citizens, are required to participate and provide accurate information to census enumerators. Failure to do so can result in penalties or fines. To ensure accuracy and consistency, a specific reference date is chosen for the census. This r re ge Z En date represents the point in time when the population's characteristics are measured. It helps minimize problems related to counting individuals who may be temporarily absent, such as vacationers or seasonal workers. Census data is usually collected through door-to-door surveys conducted by trained enumerators. However, in some cases, online forms or phone interviews, may also be used to gather information. The goal is to obtain complete and accurate data from every household and individual within the country. Government Registries A government registry is a system by which a government records all vital events of its citizens and residents. Records in the Public Registry include births, deaths, adoptions, marriages, civil unions, marriage separation, divorces, and residence permits. Every event/milestone should be registered by the individual at the relevant government registry office. Other government departments track and document the movement of individuals entering or leaving the country, enabling the compilation of immigration and emigration data and statistics. This data is collected through processes such as passport applications, issuance of visas, residence permits, and customs and border control records. POPULATIONS | 9 Population Size & Density The population size refers to the number of people in a population at a given time. Population density is a measure of how crowded a population is within a given area. It is calculated by dividing population size by land area: 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐃𝐞𝐧𝐬𝐢𝐭𝐲 = 𝐀𝐫𝐞𝐚 𝐈𝐧𝐡𝐚𝐛𝐢𝐭𝐞𝐝 𝐛𝐲 𝐭𝐡𝐞 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 Calculate the population density for Malta, given that the population is 563,443 and the land area is 316km2 (NSO, 2024). r re ge Z En Crude Birth Rate The Crude Birth Rate is a measure of the number of live births in a given year per 1000 people in a population. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐋𝐢𝐯𝐞 𝐁𝐢𝐫𝐭𝐡𝐬 𝐂𝐫𝐮𝐝𝐞 𝐁𝐢𝐫𝐭𝐡 𝐑𝐚𝐭𝐞 = × 𝟏𝟎𝟎𝟎 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 Calculate the crude birth rate for Malta for 2023, given that 4462 births were registered, and the population is 563,443 (NSO, 2024). POPULATIONS | 10 Fertility Rate The crude birth rate includes all individuals in the population, regardless of age or sex. Therefore, it gives a general sense of how many births are occurring in a population but does not account for the reproductive potential of the population. The fertility rate refers to the average number of children that would be born to a female over their lifetime. Since the fertility rate only focuses on women of childbearing age, it provides a clearer picture of reproductive behaviour and can be used to predict future population changes. The replacement level fertility rate is the average number of children that a woman needs to have during her lifetime to ensure that the population remains stable without growing or shrinking. It is often thought that the replacement level fertility should be 2.0: two parents have two children, so the population stays the same size. However, for most populations, this rate is 2.1 births per woman. This is because: Two children are needed to replace the parents: A woman needs to have two children on average - one to replace herself and one to replace the father. An extra 0.1 is needed to account for child mortality: The fertility rate is slightly higher r re ge Z En than 2 because not all children born will survive to adulthood due to factors like infant mortality, accidents, or illnesses. The additional 0.1 compensates for these losses. Crude Death Rate The crude death rate is a measure of the number of deaths in a population per 1000 individuals per year. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐃𝐞𝐚𝐭𝐡𝐬 𝐂𝐫𝐮𝐝𝐞 𝐃𝐞𝐚𝐭𝐡 𝐑𝐚𝐭𝐞 = × 𝟏𝟎𝟎𝟎 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 Calculate the crude death rate for Malta for 2023, given that 4030 deaths were registered, and the population is 563,443 (NSO, 2024). POPULATIONS | 11 Rate of Natural Increase The rate of natural increase measures the difference between the crude birth rate and the crude death rate in a population. It provides an indication of population growth based solely on births and deaths, without considering migration. 𝐑𝐚𝐭𝐞 𝐨𝐟 𝐍𝐚𝐭𝐮𝐫𝐚𝐥 𝐈𝐧𝐜𝐫𝐞𝐚𝐬𝐞 = 𝐂𝐫𝐮𝐝𝐞 𝐁𝐢𝐫𝐭𝐡 𝐑𝐚𝐭𝐞 − 𝐂𝐫𝐮𝐝𝐞 𝐃𝐞𝐚𝐭𝐡 𝐑𝐚𝐭𝐞 A positive rate of natural increase indicates that the number of births exceeds the number of deaths, and the population is growing. A negative rate of natural increase indicates that the number of deaths exceeds the number of births, and the population is declining. A rate of natural increase of zero indicates that the number of births and number of deaths are equal, and the population is stable.. Calculate the rate of natural increase for Malta for 2023, given that the crude birth rate was 7.9‰ and the crude death rate was 7.2‰ (NSO, 2024). r re ge Z En Immigration Rate The immigration rate is a measure of the number of immigrants who join a population in a given year, per 1000 people in a population. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐈𝐦𝐦𝐢𝐠𝐫𝐚𝐧𝐭𝐬 𝐈𝐦𝐦𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 𝐑𝐚𝐭𝐞 = × 𝟏𝟎𝟎𝟎 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 Calculate the immigration rate for Malta for 2023, given that 42,239 immigrants were registered, and the population is 563,443 (NSO, 2024). POPULATIONS | 12 Emigration Rate The Emigration Rate is a measure of the number of emigrants who leave a population in a given year, per 1000 people in a population. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐄𝐦𝐢𝐠𝐫𝐚𝐧𝐭𝐬 𝐄𝐦𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 𝐑𝐚𝐭𝐞 = × 𝟏𝟎𝟎𝟎 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐒𝐢𝐳𝐞 Calculate the emigration rate for Malta for 2023, given that 21,279 emigrants were registered, and the population is 563,443 (NSO, 2024). Net Migration Rate The rate of natural increase measures the difference between the immigration rate and the r re ge Z En emigration rate in a population. It provides an indication of population growth based solely on immigration and emigration, without considering births and deaths. 𝐍𝐞𝐭 𝐌𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 = 𝐈𝐦𝐦𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 𝐑𝐚𝐭𝐞 − 𝐄𝐦𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 𝐑𝐚𝐭𝐞 A positive net migration rate indicates that the number of immigrants exceeds the number of emigrants. A negative net migration rate indicates that the number of emigrants exceeds the number of immigrants. A net migration rate of zero indicates that the number of immigrants and number of emigrants are equal. Calculate the net migration rate for Malta for 2023, given that the immigration rate was 75.0‰ and the emigration rate was 37.8‰ (NSO, 2024). POPULATIONS | 13 Growth Rate The growth rate calculates the overall change in a population per year, taking into account the rate of natural increase and net migration rate. The growth rate is usually expressed as a percentage. 𝐍𝐚𝐭𝐮𝐫𝐚𝐥 𝐈𝐧𝐜𝐫𝐞𝐚𝐬𝐞 + 𝐍𝐞𝐭 𝐌𝐢𝐠𝐫𝐚𝐭𝐢𝐨𝐧 𝐆𝐫𝐨𝐰𝐭𝐡 𝐑𝐚𝐭𝐞 = 𝟏𝟎 Calculate the growth rate for Malta for 2023, given that the rate of natural increase was 0.7‰ and the net migration rate was 37.2‰ (NSO, 2024). Doubling Time The doubling time calculates how long it would take for a population to double in size if the r re ge Z En current growth rate remains unchanged. 𝟕𝟎 𝐭= 𝐆 Calculate the doubling time for Malta, given that the growth rate is 3.79% (NSO, 2024). POPULATIONS | 14 Life Expectancy The life expectancy refers to the average number of years a person is expected to live, based on the current mortality rates in a particular population. It is a statistical measure that provides an estimate of the average lifespan, therefore indicating the average age of death in a population. A high life expectancy is usually an indication of development and economic progress. This is because as countries advance, so does the level of medical care, public health, sanitation and food storage and production in the country, all of which contribute to lower mortality and a higher life expectancy. Life Expectancy & Gender Life expectancy varies by gender: female life expectancy is higher than that of males. Reasons for this are mainly biological since, across all age groups, males tend to suffer from health complications more than females. A number of socio-environmental factors may also contribute – men tend to consume more tobacco, alcohol and drugs than women and are likelier to die from associated accidents and diseases and men also tend to pursue high risk occupations such as construction, mining, or r re ge Z En military roles more than women. Differences also exist in healthcare utilization and health-seeking behaviour. Females have higher rates of healthcare utilization and health seeking, including preventive care and regular screenings, which can contribute to earlier detection and management of health conditions, leading to better outcomes and longer life expectancy. Sex Ratio The sex ratio refers to the proportion of males and females in a population. It is usually expressed as the number of males per 100 females, or as a ratio. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐌𝐚𝐥𝐞𝐬 𝐒𝐞𝐱 𝐑𝐚𝐭𝐢𝐨 = 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐅𝐞𝐦𝐚𝐥𝐞𝐬 The sex ratio at birth refers to the ratio of male to female births in a population. At conception, the sex ratio is equal and there is no difference in the number of males and females that are conceived. However, during pregnancy, female mortality appears to be slightly higher than male mortality. As a result, more boys are born than girls and the global sex ratio at birth is about 1.05. POPULATIONS | 15 Following birth, and as life progresses, male mortality increases and the male-bias in the sex ratio tends to weaken. Thus, the sex ratio decreases over the course of life from being male- biased at birth to being female-biased at old age. Sex Ratio in Different Countries Most countries have a sex ratio of approximately 1, meaning an approximately equal number of males and females within a population. In some parts of the world, the sex ratio of a population is not 1 since it is greatly influenced by various factors such as migration patterns, cultural practices and differential mortality rates. Calculate the sex ratio for Malta for 2023, given that there were 298,746 males and 264,697 females residing in Malta (NSO, 2024). Are there more Males or Females in the World? When considering all ages, the global sex ratio should even out since more boys are born than girls and women live longer than men. However, the ratio of men to women is not exactly r re ge Z En equal and the sex ratio is about 1.01, i.e. 101 males, for every 100 females. Reasons for this are related to “missing women” as a result of gender discrimination and societal practices. The concept of missing women was first popularized by economist Amartya Sen in the 1990s, who estimated that millions of women were "missing" due to factors like sex-selective abortion, female infanticide, unequal access to healthcare and nutrition and gender-based violence. Dependency Ratio The dependency ratio compares the proportion of the dependent population (those who are not part of the labour force) to the working-age population (typically those aged 17-64). It provides insight into the economic pressure on the productive population to support those who are too young or too old to work. The total dependency ratio combines both the youth and elderly ratios, indicating the total number of dependents (young and old) that each 100 people of working age must support. 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐘𝐨𝐮𝐧𝐠 𝐃𝐞𝐩𝐞𝐧𝐝𝐞𝐧𝐭𝐬 + 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐀𝐠𝐞𝐝 𝐃𝐞𝐩𝐞𝐧𝐝𝐞𝐧𝐭𝐬 𝐃𝐞𝐩𝐞𝐧𝐝𝐞𝐧𝐜𝐲 𝐑𝐚𝐭𝐢𝐨 = × 𝟏𝟎𝟎 𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐨𝐩𝐮𝐥𝐚𝐭𝐢𝐨𝐧 POPULATIONS | 16 Young Dependents In this age range, individuals are not part of the labour force due to being in the early stages of development, education, and growth. At these ages, individuals are economically dependent on their parents or guardians, for their basic needs like food, shelter, education, and healthcare. Aged/Elderly Dependents In this age group, individuals are usually retired and no longer part of the labour force. In many countries, 65 is the typical retirement age, marking the point at which people often stop working full-time and become economically dependent on pensions, social security and financial support from others (such as family or the state) to meet their living expenses. Calculate the dependency ratio for Malta for 2023, given that there were 74,125 people below the age of 15, 385,912 people aged between 16 and 64 and 103,406 people above the age of 65 (NSO, 2024). r re ge Z En Low Dependency Ratio A low dependency ratio refers to a situation where the proportion of dependents is small compared to the working-age population. As a result, there are fewer people reliant on the working population, making it ideal for maintaining economic and social stability and progress. In the long term, a low dependency ratio could result in economic strain when the working population shrinks and the elderly population grows. High Dependency Ratio A high dependency ratio refers to a situation where there is a large proportion of dependents compared to the working-age population. A high dependency ratio is not ideal for a country's economy because it means fewer people are in the workforce, which can strain the productive part of the economy. There are fewer workers supporting more people who rely on public services such as healthcare, pensions, and education. A high youth dependency ratio refers to a situation where there are many young dependents placing a burden on the working-age population while a high aged dependency ratio refers to a situation where there are many elderly dependents placing a burden on the working-age population. POPULATIONS | 17 Demographic Transition Model The Demographic Transition Model (DTM) illustrates historical and projected shifts in population trends and patterns as countries go through different stages of economic development. It illustrates how populations shift from high birth rates and high death rates to low birth rates and low death rates, as a result of economic development, from a pre-industrialized society to an industrialized and affluent one. r re ge Z En Stage Birth Rate Death Rate Population Growth 1 High High Stable or Low 2 High Falling Rapid Increase 3 Falling Falling Slowing Down 4 Low Low Stable 5 Very Low Low Decline Stage 1 (High Stationary/Fluctuating) Stage 1 of the DTM is characterized by high birth rates and high death rates, which fluctuate but tend to balance each other out over time, leading to a very slow or stagnant population growth. This stage is often associated with pre-industrial societies. No countries are currently in Stage 1 of the DTM today, but historical examples include most of the world prior to the Industrial Revolution. However, there are still a few remote and isolated populations that exhibit characteristics of Stage 1 due to limited access to modern healthcare and economic opportunities. Examples include indigenous tribes in remote areas of South America (such as in the Amazon), Africa and parts of Southeast Asia. POPULATIONS | 18 High Birth Rates Need for Labour: Most societies in Stage 1 are primarily agrarian and rely on agriculture as the main source of livelihood. High birth rates are advantageous in these societies as they help ensure an adequate labour force for agricultural activities. Lack of Contraceptives and Family Planning Services: Limited access to birth control or knowledge about family planning contributes to high fertility. High Infant and Child Mortality: Due to high infant and child mortality rates, families often have many children in the hopes that at least some will survive to adulthood. Cultural Norms and Traditional Beliefs: Cultural norms and traditional beliefs often emphasize the importance of having large families. In many societies, children are seen as a blessing or as a form of social status. Early Marriages: Early marriages are common in Stage 1 societies, leading to longer reproductive periods for women. Marrying young increases the total number of potential childbearing years, contributing to higher birth rates. High Death Rates Poor Medical Knowledge and Healthcare: Stage 1 societies are characterised by limited r re ge Z En access to modern medicine and healthcare services. As a result, healthcare services, effective treatments, antibiotics and disease prevention in the form of vaccinations are very limited. Diseases that are easily treatable today, such as cholera, typhoid, smallpox, and influenza, are often fatal in Stage 1 societies. Famine and Food Shortages: Being agrarian, stage 1 societies are heavily dependent on the weather and environmental conditions. Crop failures due to drought, floods, or other natural disasters lead to widespread famine. Lack of Sanitation and Clean Water: In stage 1 societies, clean water and sanitation systems are either non-existent or extremely rudimentary. This resulted in waterborne diseases being widespread and deadly. Human waste and garbage often accumulated near living areas, contributing to the spread of infectious diseases. Stable Population Growth With both birth rates and death rates high but relatively balanced, population growth is slow or stagnant. The high birth rates compensate for the high death rates, resulting in little overall population growth. This equilibrium keeps the population size relatively stable over time. POPULATIONS | 19 Stage 2 (Early Expanding) As societies undergo improvements in agriculture, sanitation, medical care, and overall living conditions they progress to Stage 2 of the DTM. Stage 2 of the DTM is characterised by high birth rates and declining death rates and represents a critical phase in the transition from a pre-industrial society to one with rapid population growth. Many of the least developed countries in the world today are in Stage 2. Progression to Stage 2 in more developed nations occurred early in the 1800s, after the Industrial Revolution. On the other hand, the shift to stage 2 by less developed nations only began in the 1950s. High Birth Rates Birth rates remain high for the same reasons as Stage 1. As societies begin to transition towards industrialization, there are still many economic incentives to have more children: larger families are seen as an asset, with children viewed as a source of labour or future income earners. Traditions that favour large families also persist, as cultural change tends to lag behind improvements in health and mortality. Declining Death Rates r re Advances in Medical Care: The introduction of vaccines, antibiotics, and other medical ge Z En treatments significantly reduces mortality from infectious diseases. Improvements in medical knowledge and healthcare infrastructure also lead to lower death rates. Improvements in Public Health: Better sanitation, clean water supplies, and initiatives to promote hygiene practices, such as using soap, proper waste disposal, and maintaining personal cleanliness, all help reduce disease and lower mortality. Improvements in Nutrition and Food Security: Advances in agriculture, such as the use of fertilizers, crop rotation, and improved irrigation, increase food production. Better food distribution and storage also contribute to better nutrition, lowering death rates. Urbanization and Infrastructure: As societies urbanize, there is usually better access to food and healthcare services. As transportation and communication infrastructure improve, this helps in the distribution of food and medical supplies to more people. High Population Growth As death rates decline and birth rates remain high, countries experience rapid population growth. Although birth rates sometimes grow in stage 2, most population increase is due to a decline in deaths. As the gap between birth and death rates widens, there is a large increase in the size of a population. POPULATIONS | 20 Stage 3 (Late Expanding) As societies start to urbanise and industrialise, they progress to Stage 3 of the DTM, which is characterised by declining birth and death rates. It represents a phase in the transition from a society with rapid population growth to one that will eventually stabilise in Stage 4. Progression to stage 3 in those countries currently in later stages of the model began late in the late 1800s / early 1900s, while progression from stage 2 to stage 3 by countries currently at this stage began in the 1980s. Declining Birth Rates Shift to Industrial Economies: As countries move away from agrarian economies, the demand for manual labour decreases. This diminishes the economic incentive to have many children for labour. Lower Infant Mortality: With advancements in healthcare, the survival rate of infants increases. Parents no longer feel the need to have many children to ensure that some will survive to adulthood. Access to Contraceptives and Family Planning: Programs that offer affordable and accessible contraception and family planning services are implemented. These play a vital role in educating families and providing them with greater control over r re ge Z En reproduction, enabling informed decisions about family size. Education and Empowerment of Women: As girls gain access to education, their priorities often shift from early marriage and childbearing to personal development and career goals. Women who pursue higher education or career opportunities often delay marriage and childbirth, leading to a natural decline in the birth rate. Declining Death Rates Death rates continue to decline for the same reasons as Stage 2 and are improved upon. Improved sanitation, clean water, and hygiene education significantly reduce infectious diseases and lower mortality rates. Agricultural advancements and better access to nutritious food enhance health and decrease death rates. Access to healthcare services, advancements in medical technology, and increased availability of healthcare facilities help reduce mortality rates. Improved healthcare infrastructure, vaccination programs, and disease prevention measures contribute to longer life expectancy. POPULATIONS | 21 High Population Growth Stage 3 is characterized by a slower population growth compared to Stage 2. As birth rates decline while death rates remain relatively low, the gap between the two narrows, resulting in slower population growth. The overall population size continues to increase but at a reduced rate compared to earlier stages. Stage 4 (Low Stationary/Fluctuating) Stage 4 is characterized by low birth rates and low death rates, leading to a relatively stable population size. Countries in this stage typically have well-developed economies, higher standards of living, and advanced healthcare systems. The focus shifts from concerns of high population growth to challenges associated with an ageing population and potential labour force shortages. Many of the most developed countries around the world today are in Stage 4 of the DTM. Progression from stage 3 to stage 4 in more developed countries began after the 1970s but has not begun in less developed countries. Low Birth Rates r re ge Z En Higher Levels of Education: In Stage 4, more women pursue higher education and prioritize career advancement, financial independence, and lifestyle aspirations over having large families. Active Female Participation in the Workforce: As more women join the workforce large families become less common. Full-time jobs require substantial time and energy, making it challenging to balance work with the demands of raising many children. Urbanisation and High Costs of Living: The high cost of living in urban areas, including housing, healthcare, education, general expenses and raising a child, discourages large families. Access to Contraception and Family Planning Services: In Stage 4, many contraceptive methods are widely available and affordable, allowing couples to control the number and timing of their children. Cultural Shifts: Societal values change significantly in Stage 4, with a preference for small, nuclear families over large, extended families. Furthermore, delaying marriage and childbirth becomes socially acceptable, and non-traditional family structures (single-parent households, child-free couples, etc) become more common. POPULATIONS | 22 Low Death Rates Modern Medical Care: Access to advanced medical technologies and treatments helps to prevent and effectively manage illnesses that were once fatal. This includes high quality hospitals, trained medical professionals, and advanced surgical procedures. Vaccination programs, routine check-ups and early detection programmes help prevent diseases before they become life-threatening. Improved Public Health: Clean water, proper sanitation, modern sewage disposal systems and better hygiene practices are all present and reduce the spread of infectious diseases. Increased awareness about health, disease prevention, and the importance of nutrition contribute to healthier lifestyles. Social Services and Welfare: Many Stage 4 countries have social security systems, unemployment benefits, and pension schemes, which reduce economic insecurity and help individuals maintain good health throughout their lives. With an ageing population, Stage 4 countries often have programs that specifically address the healthcare needs of the elderly, including home care services, nursing homes, and specialized medical treatments. Policies and Infrastructure: Governments in Stage 4 countries often implement policies r re ge Z En and programs that directly support public health, such as disease eradication campaigns, subsidized healthcare, and emergency medical services. Governments also help to reduce deaths from natural disasters and emergencies through procedures for disaster management, like early warning systems and rapid response teams. Low Population Growth In Stage 4, birth rates are generally balanced with death rates, resulting in near-zero population growth. The population size remains relatively stable over time, with small variations due to natural fluctuations. Stage 5 (Declining) Progression to stage 5 of the DTM is a fairly recent phenomenon that began in the late 1900s and early 2000s. Only a few countries (Germany, Italy and Japan) are at this stage, but many European countries are moving in this direction. POPULATIONS | 23 Low Birth Rates Economic Factors: In Stage 5 countries, the cost of raising children is significantly high, including expenses related to education, housing, healthcare, childcare and basic needs like food and energy. This makes larger families less affordable. Work-Life Balance Challenges: In some cases, career advancement may be incompatible with having large families due to demanding work environments, insufficient parental leave, or inadequate childcare options. Small Living Spaces: As urbanization increases, living spaces tend to shrink, making it less practical or desirable for families to have multiple children. Individualism and Personal Freedom: In many Stage 5 societies, there is a greater emphasis on personal fulfilment, career goals, independence and acquisition of material goods, rather than having children. Low Death Rates In Stage 5, death rates remain low for the same reasons as in Stage 4, despite potential population decline. This is largely because countries in this stage have advanced healthcare systems and high living standards. r re ge Z En Although Stage 5 countries may have ageing populations, the elderly benefit from geriatric care, assisted living facilities, and medical advances that allow them to live longer. Life expectancy increases as death rates remain low, even among older people. Negative Population Growth In Stage 5, population growth is negative (or declining) due to the combination of low birth rates and low death rates. As declining birth rates outpace declining death rates, the population size will shrink over time. This scenario usually leads to demographic challenges associated with an ageing population and a high aged dependency ratio. Limitations of the Demographic Transition Model Regional and Cultural Variations between Countries Incomplete Representation of Factors Limited Attention to Government Policies and Incentives Non-Linear Transitions POPULATIONS | 24 Population Pyramids A population pyramid, or age-gender diagram, is a graphical representation that displays the distribution of a population's age and gender composition. It provides a snapshot of a population structure using two back-to-back graphs (one for each gender), with population size or percentage on the x-axis and age (in 5-year intervals) on the y-axis. Males are usually shown on the left while females are shown on the right. Interpreting a Population Pyramid Each of the individual bars shows the number of people in a particular age group. Their ages are shown in a shared label in the middle y-axis while the amounts are shown on the x-axis. Birth Rate: This can be inferred from the width of the base (the youngest age group, typically 0-4 years). A wide base indicates a high birth rate because it shows a large r re ge Z En proportion of young children in the population. A narrow base suggests a low birth rate, reflecting fewer children being born. Death Rate: This can be inferred from how the population size decreases in older age groups. A rapid decline in population size as you move up the age groups suggests a high death rate. A gradual tapering of the pyramid indicates a lower death rate, with more people surviving into older age. Life Expectancy: This can be inferred from the height of the pyramid. A tall pyramid (with many people in the 60+ age groups) indicates a high life expectancy. A shorter pyramid (where few people survive beyond 60) points to a lower life expectancy. Sex Ratio: This can be inferred by comparing the two sides of the pyramid. If the bars are roughly equal, the sex ratio is balanced but if one gender's bar is larger than the other across most age groups, then the sex ratio is skewed in favour of that gender. Dependency Ratio: This can be inferred by comparing the proportion of youth (0-15 years) and elderly (65+) relative to the working-age population (16-64 years). Many youth or elderly, compared to a small working population indicates a high dependency ratio. POPULATIONS | 25 Population Pyramid Age Groups Population pyramids often categorize age groups into three main categories: Pre-Reproductive (0-14 Years): These individuals are typically too young to reproduce and are dependent on others for care and support. Reproductive (15-44 Years): Individuals in this group are the primary contributors to the population growth rate through reproduction. Post-Reproductive (45+ Years): People in this age group are no longer contributing directly to population growth through reproduction. Population Pyramid Shapes Growing Populations A population pyramid for a growing population typically has a wide base, indicating a high proportion of young individuals in the pre-reproductive age group. In such populations, the segment of the population that is in its childbearing years (reproductive age group) normally produces a generation that is larger than itself. r re ge Z En In most cases, as the pyramid moves upward through older age groups, the bars gradually shorten, reflecting a lower number of people in older age cohorts. The top of the pyramid is much narrower, showing a small proportion of elderly people due to shorter life expectancies or high mortality rates. A pyramid showing rapid population growth will have a very wide base, with a sharp tapering as you move up the age groups. A pyramid for slow population growth still shows growth, but it is less sharp. The base will still be wider than the top, but the sides of the pyramid taper more gradually. POPULATIONS | 26 Stable Populations A stable population pyramid tends to have a more balanced distribution across all age groups. Overall, the pyramid resembles more of a block shape, with a slight narrowing at the top. The base is not excessively wide, indicating fairly low birth rates. The number of children being born is just enough to replace the population. The middle section remains steady, with roughly equal numbers of people in each age cohort and no sharp drops or bulges. The top of the pyramid (older age groups) gradually tapers, as fewer people reach the older age brackets. Declining Populations r re ge Z En A population pyramid for a declining population generally has a narrow base, indicating a low proportion of young individuals. The reproductive age group might still be present but is less prominent, and the post-reproductive age group is larger in comparison to the younger age groups. Sometimes, the post-reproductive group may be the largest group. The sides of the pyramid often curve inward, especially at the base, highlighting the reduced number of births compared to past generations. The result is a shape that may resemble a cone or an inverted triangle. This type of population pyramid is indicative of countries with an ageing population and low fertility. POPULATIONS | 27 Population Structures of MEDCs and LEDCs Less Economically Developed Countries (LEDCs) Less Economically Developed Countries are countries typically in stage 2 (and sometimes stage 3) of the Demographic Transition Model. They are characterised by low economic productivity, poor healthcare services, weak infrastructure and low accessibility to education. Population Pyramids of LEDCs Population pyramids in LEDCs are usually characterised by a wide base (indicating high birth rates) and a narrow top (indicating high death rates and a low life expectancy). r re ge Z En As a result, LEDCs have a youthful population with a higher proportion of youths in the population structure and relatively few older adults. This population structure often leads to potential population growth due to the high number of individuals entering reproductive age, even if birth rates eventually decline. Implications of a Youthful Population Increased Demand for Education A youthful population leads to a surge in demand for education as more children require access to schools and learning resources. This translates into a greater need for educational facilities and resources, such as schools, teachers and textbooks. Schools might face overcrowding, and governments may need to invest more in building and maintaining educational infrastructure. Providing quality education becomes a challenge when resources are stretched thin. POPULATIONS | 28 Increased Demand for Healthcare A high young age dependency ratio means more children, who require healthcare services and vaccinations. The demand for paediatric care, child immunizations, and maternal healthcare services increases. Governments must allocate resources to expand healthcare infrastructure, train healthcare professionals, and ensure access to medicines. Failure to meet these needs can lead to higher child mortality rates and long-term health challenges. Unemployment and Job Market Pressure As the large youth cohort grows older, they will eventually enter the labour market. If the economy is not able to create enough jobs, this could lead to high youth unemployment, which may lead to frustration, social unrest, protests, or political instability, especially in countries with weak governance. Brain Drain Limited opportunities can lead to higher rates of emigration, as young people move in search of better jobs, education, and quality of life. When countries lose their most talented, skilled, and educated individuals, it negatively impacts their potential for economic development since the same individuals who could drive innovation, productivity, and future development r re ge Z En are no longer contributing to their home country’s economy. Addressing Youthful Populations and a High Youth Dependency Ratio Enhancing Healthcare When parents are confident that children will grow up healthy, they are less likely to have many children as a precaution against child mortality. Therefore, investing in healthcare for a youthful population ensures better survival rates, reducing the perceived need for larger families. Access to vaccinations, prenatal and postnatal care, nutrition programmes and treatment of childhood diseases all promote healthier lives, ultimately reducing child mortality. Access to Contraception and Family Planning Services Providing access to contraception and family planning services allows individuals to make informed decisions about the number and spacing of their children and reduces the number of unplanned pregnancies. By ensuring that contraception is affordable and accessible, governments can help decrease fertility rates, which leads to lower population growth. POPULATIONS | 29 Supporting Women’s Empowerment Educating girls and women has a direct correlation with reduced fertility rates, as educated women are more likely to marry later, have fewer children, and seek employment. Women who work face opportunity costs associated with having more children, such as lost income, career advancement, and time away from work. The higher these opportunity costs, the more likely women are to limit the number of children they have. Anti-Natalist Policies and Legislation Governments may implement policies to incentivize less children. These include benefits such as free healthcare and education, but only for a certain number of children. In some cases, legal restrictions on reproduction are imposed, such as by introducing penalties or reducing access to government benefits for having more than a set number of children. More Economically Developed Countries (MEDCs) More Economically Developed Countries (MEDCs) are countries typically in stages 4 or 5 of the Demographic Transition Model. They are usually characterised by high economic productivity, good healthcare services, good infrastructure and a high standard of education. r re ge Z En Population Pyramids of MEDCs Population pyramids in MEDCs are usually characterised by a narrow base (indicating low birth rates) and a wide top (indicating low death rates and a high life expectancy). As a result, MEDCs have an ageing population with a higher proportion of elderly in the population structure and relatively few younger adults. This trend may lead to a stable or even decreasing population over time. POPULATIONS | 30 Implications of Ageing Populations Increased Pressure on Pension Systems An ageing population leads to a higher proportion of retirees, which puts pressure on pension systems. As the number of beneficiaries increases, the funds required to sustain pension payouts rise, potentially leading to financial strain on governments and pension providers. Smaller Workforce and Decreased Tax Revenue As the population ages, the ratio of working-age individuals to retirees decreases, resulting in a smaller workforce. This can hinder economic growth, as fewer workers are available to drive productivity and innovation. Additionally, with fewer people earning wages, tax revenues decline, which reduces the government’s ability to fund public services and maintain infrastructure, healthcare, and other essential services. Increased Pressure on Healthcare Systems As the elderly population grows, the demand for medical care, long-term care, and specialized services increases. This will require more funding and physical and human resources to provide adequate and quality healthcare services. The demand for long-term care services, r re ge Z En including nursing homes, homes for the elderly and home healthcare will also increase significantly, leading to challenges in providing suitable options. Changes in Household Dynamics Ageing populations alter household structures, with more elderly family members living with or depending on younger relatives. This shift places additional financial, emotional, and time- related burdens on working-age individuals who must adapt to caring for ageing relatives while managing their own responsibilities. Multi-generational households are becoming more common, as older individuals depend more on their children for support Addressing Ageing Populations and a High Aged Dependency Ratio Raising the Retirement Age Raising the retirement age addresses aging populations by keeping older individuals in the workforce longer, reducing pressure on pension systems, and maintaining a pool of experienced workers. This approach increases the labour force participation rate, enhancing economic productivity and easing the financial burden on public funds for supporting retirees. POPULATIONS | 31 Increasing Taxes Increasing taxes can generate additional revenue to fund pensions, healthcare, and other services required by an aging population. This helps address rising costs associated with an older demographic, especially as more people retire. However, higher taxes can be a burden on the working-age population and may reduce disposable income Introduction of Family Friendly Policies Family-friendly policies, such as flexible working hours, parental leave, and affordable childcare, make it easier for individuals to balance work and family responsibilities. These policies can encourage higher birth rates by reducing the financial and time-related barriers to having children, ultimately helping to replenish the population and workforce. Introduction of Pro-Natalist Policies Pro-natalist policies aim to increase birth rates through financial benefits, tax breaks, subsidized childcare, child allowances, improved parental leave and cultural rewards. By alleviating the financial burden of raising children, these policies encourage families to have more children, helping to offset the effects of an aging population and rejuvenate the population over time. r re ge Z En Promoting Immigration Pro-natalist policies aim to increase birth rates through financial benefits, tax breaks, subsidized childcare, child allowances, improved parental leave and cultural rewards. By alleviating the financial burden of raising children, these policies encourage families to have more children, helping to offset the effects of an aging population and rejuvenate the population over time. Investing in Technology and Automation Investing in technology and automation helps mitigate the effects of an ageing population by compensating for labour shortages and boosting productivity. Automation in industries such as manufacturing, agriculture, and healthcare can maintain high output levels even with fewer workers. It can also reduce the physical demands on older workers, enabling them to stay employed longer. POPULATIONS | 32 History of Human Population Growth Homo sapiens is the only extant species of the genus Homo. Other species within the genus Homo, such as Homo neanderthalensis, Homo erectus and Homo habilis have become extinct over time. The earliest fossil evidence of early Homo sapiens, or anatomically modern humans, was found in Africa. r re ge Z En Palaeolithic Humans The Palaeolithic Period spanned from about 2.5 million years ago until around 10,000BC. Palaeolithic humans were primarily hunter-gatherers, relying on hunting animals and gathering wild plants, eggs and seafood for sustenance. They sought shelter in caves in small groups and probably relied on strong social bonds for survival, with communal sharing of food and resources. Cooperation in hunting, gathering, and child-rearing would have been essential. Palaeolithic humans were also nomadic: movement out of areas was very common, especially when resources, such as food, were depleted. A result of this movement was migration from Africa to all continents. About 70,000 to 50,000 years ago Homo sapiens begin to migrate out of Africa, first to Europe and Asia and then to Australia, and the Americas. It is believed that this migration was slow and occurred in multiple waves. POPULATIONS | 33 High Birth Rates Palaeolithic humans had relatively high birth rates to ensure the survival and continuity of the group. Women likely had multiple children during their reproductive years, with childbirth occurring at relatively young ages. High Death Rates Life in the Palaeolithic Period was challenging, with various risks and hazards. Exposure to environmental dangers, hunger, accidents, injuries and disease, together with limited medical knowledge and a lack of sanitation, all contributed to relatively high death rates. High Infant Mortality Rates: Due to the harsh living conditions and limited access to medical care, many children did not survive infancy. Natural threats, such as disease, accidents, or food scarcity, contributed to a high infant mortality rate, which hindered population growth. Fewer Individuals Reaching Reproductive Maturity: Life expectancy was generally low during the Palaeolithic period, with many individuals not surviving long enough to reproduce. Environmental dangers, nutritional challenges, and competition for resources further reduced the number of people who could live to reproductive age. r re ge Z En Population Growth Population growth during the Palaeolithic period was relatively slow. High birth rates and high death rates kept population sizes in check, and it is very likely that populations could not expand beyond the size that food sources supported. By 12,000 years ago, the global population reached 4 million people. Neolithic Humans: The Agricultural Revolution In around 10,000BC, a major discovery revolutionized human society. People in the Middle East began to develop the first farming and herding, ushering in the start of the Agricultural Revolution and the Neolithic Period of human civilization. The Agricultural Revolution marks a significant shift in human history since Neolithic humans transitioned from relying on hunting and gathering to practicing agriculture. They cultivated crops such as wheat, barley, rice, maize, and domesticated animals like cattle, sheep, goats, and pigs. Farming and animal husbandry became central to their subsistence. POPULATIONS | 34 As people learnt how to grow crops and domesticate animals, more food was being produced than hunting and gathering, and in a smaller space. Agriculture provided a more abundant and permanent food supply and led to an overall increase in the global population from 4 million in 10,000BC to about 200 million at 1AD. The development of agriculture also meant that it was no longer necessary to keep moving to locations where food was available. As a result, agriculture also made it possible to shift from a nomadic lifestyle to a settled one, forming the first permanent settlements and villages near fertile land and water sources. Agriculture also promoted the ability to control and store food (such as grains) for future use. This stability reduced the risks of famine compared to the unpredictable food sources in hunter-gatherer societies and helped to support larger populations. Higher Birth Rates With settled communities, more stable food resources, and the need for field workers, Neolithic societies likely experienced higher birth rates compared to Palaeolithic ones. Increased food security and sedentary lifestyles may have contributed to a greater number of children per woman. r re ge Z En Lower Death Rates Death rates in the Neolithic were still high, but relatively lower when compared to the Palaeolithic period. The development of settled communities allowed access to a more diverse diet. However, disease and injury were still prevalent, and some societies and civilizations collapsed due to famine or social conflicts. Population Growth Overall, the Agricultural Revolution brought about significant changes in population dynamics. The adoption of agriculture, surplus food production, and sedentary settlements facilitated population growth. The ability to support larger populations and a more stable food supply allowed communities to expand in size. The Pre-Industrial Period Advances in farming and increased non-farming roles, caused villages to grow and eventually develop into cities. The development of cities eventually gave rise to the first complex and organized societies, or civilizations. The first civilizations grew along rivers where enough food could be grown to support an expanding population. POPULATIONS | 35 The world population continued to increase slowly from the end of the Neolithic Period up to 1347AD, when the Black Death began. The Black Death The Black Death of the 14th Century was the result of the bubonic plague: it is the worst and most devastating pandemic in human history. Both the cause and the cure were surrounded by ignorance. As a result, the impact on the world population was enormous. About one third of Europe’s population was killed and the world population was reduced from 450 million to 350 million. In some regions, mortality rates reached as high as 90%. It took between 50 and 100 years for the world population to recover and start increasing once again. The Black Death brought with it a high mortality rate, leading to widespread labour shortages, especially in the most impacted areas. This shortage increased wages for workers and gave peasants more bargaining power. Additionally, with fewer people to work the land, many fields were left fallow, prompting changes in agricultural practices and a push for innovation in labour-saving technologies. As the Black Death subsided, humanity began to acknowledge and accept its ignorance in understanding the world. This shift in mindset marked a turning point in the way people r re ge Z En approached knowledge. Traditional beliefs and ideas were challenged, while new theories and concepts emerged. As a result, significant intellectual and scientific progress was made, particularly in the development of the scientific method and advancements in astronomy, physics, chemistry, biology, and medicine. Furthermore, this Scientific Revolution laid the groundwork for the Industrial Revolution that followed. The Industrial Revolution The Industrial Revolution refers to the period of social, economic, and technological change that occurred in the 18th and 19th centuries, primarily in Europe and North America. It marked a shift from an agrarian, labour-intensive economy to one characterized by mechanized production, industrialization, and urbanization. This revolution brought about significant advancements in manufacturing, transportation, and communication, transforming society and the global economy. Industrialization led to increases in production capacity, affecting all basic human needs, such as food, medicine, housing, and clothing: not only did society develop the ability to have more things faster (mass production) but it would be able to develop better things (new products). POPULATIONS | 36 Prior to the Industrial Revolution, the world population had been slowly increasing after the Black Death about 300 years earlier, reaching approximately 700 million in 1750. One of the key factors driving population growth during and after the Industrial Revolution was a significant decline in mortality rates. Although death rates fell, birth rates remained high, which meant that growth was assured unless fertility fell. Since the onset of the Industrial Revolution, the global human population has undergone a dramatic transformation, culminating in a population explosion. About 250 years after the Industrial Revolution began, the world population has grown to approximately 8.2 billion. The Impact of the Industrial Revolution on Human Populations Improved Living Conditions and Lower Mortality Rates: Advancements in medicine, sanitation, and public health (like improved water supplies and sewage systems) dramatically decreased death rates, especially among children. Diseases like smallpox and cholera became less prevalent. Increased food production: Agricultural innovations like crop rotation, new machinery, and improved fertilizers boosted food production, leading to better nutrition and reduced starvation. r re ge Z En Job creation: Industrialization created new jobs in factories and mines, providing income and supporting larger families. Urbanization: The growth of cities provided opportunities for employment and a concentration of resources, further contributing to population growth. Current and Future Trends Projections by the United Nations show that world population growth will slow significantly over the course of the 21st century and should come close to 9 billion in 2037, 10 billion between 2055 and 2057 and 11 billion by 2100. 11 billion is often viewed as the peak of the human population and should plateau at that level. Until the peak is reached, population growth in different countries will follow different patterns, based on the level of economic development of that country. Population growth will be at its highest in developing countries and lowest in developed countries. POPULATIONS | 37