Human Population Environmental Science

What is a Population? Population - all the members of a certain species in a certain area. Population - all the members of a certain species in a certain area. Human population- All the members of the human race on Earth.Human population- All the members of the human race on Earth. Why on ALL of Earth?Why on ALL of Earth? –Humans have used technology to adapt and be able to easily move from anywhere on Earth to anywhere else.

Population Changes Populations grow when the birth rate is greater than the death rate.Populations grow when the birth rate is greater than the death rate. –Birth rate-number of organisms reproduced in a year –Death rate- number of organisms that perish in a year

Population Change Populations can decrease if the death rate is greater than the birth rate.Populations can decrease if the death rate is greater than the birth rate.

Limiting Factors to Population Growth Limiting Factor- Anything that limits how many individuals a certain population will have Limiting Factor- Anything that limits how many individuals a certain population will have – Food supply- If there’s not enough food for every organism to grow and carry out life functions, then some organisms will die – Space -If there isn’t enough habitat, some organisms will die –Predation/Disease- If there are no predators/disease, a population can increase

White Tail Deer Around 1900, the white tail deer in NY population was very low.Around 1900, the white tail deer in NY population was very low. –Due to almost no habitat, and unregulated human hunting –Efforts were made to limit hunting –Forest habitats started to increase as agriculture in NY decreased Now, in 2008, the white tail population is enormousNow, in 2008, the white tail population is enormous –Due to regulated hunting and no natural predators –Abundant food sources and a TON of habitat

Carrying Capacity Carrying capacity- The total number of individuals that a certain habitat can support and sustain. Carrying capacity- The total number of individuals that a certain habitat can support and sustain. Carrying capacity is based on the limiting resources of a given habitat.Carrying capacity is based on the limiting resources of a given habitat. When a population exceeds its carrying capacity, it will rapidly decrease (crash) until it is below the carrying capacityWhen a population exceeds its carrying capacity, it will rapidly decrease (crash) until it is below the carrying capacity

Easter Island The inhabitants of Easter Island were so numerous that they used up all of their resources.The inhabitants of Easter Island were so numerous that they used up all of their resources. When the resources were all gone, many people killed each other for the scarce food and water that was left.When the resources were all gone, many people killed each other for the scarce food and water that was left. Other people starved, until the population was very, very smallOther people starved, until the population was very, very small

Human Population Growth With the invention of new technologies, the human population has exploded from just 200 million ~8000 B.C. to 6.6 billion today.With the invention of new technologies, the human population has exploded from just 200 million ~8000 B.C. to 6.6 billion today.

Human Society Human Society has changed over timeHuman Society has changed over time Hunter-Gatherer Society- Humans lived in small bands and spent most of their time looking for food Hunter-Gatherer Society- Humans lived in small bands and spent most of their time looking for food Agricultural Society- Humans spent time in small cities and towns, in one place, and spent most of their time growing food. Agricultural Society- Humans spent time in small cities and towns, in one place, and spent most of their time growing food. Industrial Society- Humans live in larger communities, but can freely travel, and spent most of their time pursuing money, rather than food. Industrial Society- Humans live in larger communities, but can freely travel, and spent most of their time pursuing money, rather than food.

Human Population Growth There are three stages of population growth:There are three stages of population growth: –1. Pre-agricultural societies: birth rate and death rates are high, but close to equal, so the population grows slowly –2. Agricultural societies: population size increases due to an increase in health care resulting in higher birth rates and lower death rates. –3. Industrial society-Birth rates fall until they are roughly equal to death rates, resulting in zero population growth.

Why the changes in population growth? Agricultural : population increases because level of health care increases, but the birth rate doesn’t decrease. In an agricultural society, children are an asset. Agricultural : population increases because level of health care increases, but the birth rate doesn’t decrease. In an agricultural society, children are an asset. Industrial : The population levels out and stops increasing because of advances in technology, but also because children become economic liabilities, rather than assets. Industrial : The population levels out and stops increasing because of advances in technology, but also because children become economic liabilities, rather than assets.

Population Pyramid Population Pyramid: a graph showing the number of males and females in each age group in a country’s population.Population Pyramid: a graph showing the number of males and females in each age group in a country’s population.

Japan Japan’s three population pyramids shows the three kinds of population growth.Japan’s three population pyramids shows the three kinds of population growth Rapid growth, the birth rate is greater than the death rate Rapid growth, the birth rate is greater than the death rate Slowing growth, the birth rate is greater than the death rate, but not by much2006- Slowing growth, the birth rate is greater than the death rate, but not by much Zero growth, or negative growth, the death rate exceeds the birth rate Zero growth, or negative growth, the death rate exceeds the birth rate.

Japan

Problems with Population Growth Pollution - increased people means more pollution Pollution - increased people means more pollution Shortage of natural resources- As more people consume more and more, we will run out of some resources Shortage of natural resources- As more people consume more and more, we will run out of some resources Space -Where will we put all these people and still have lands to support them? Space -Where will we put all these people and still have lands to support them?

Solutions? We need to consume less!We need to consume less! Work for a sustainable future.Work for a sustainable future. –Sustainable- being able to support a certain population indefinitely