19.3 The Human Population

Population ecologists theorize that species that evolve suites of characteristics may lead to particular adaptation to their environments.

The kind of population growth their species experience is impacted by these adaptations.
Life history characteristics such as birth rates, age at first reproduction, the number of offspring, and even death rates evolve just like behavior, leading to changes that affect population growth.
There are species on the other.
The species tend to be close to their carrying capacity.
The species tend to have larger, but fewer, offspring and contribute more resources to each offspring.
There are a lot of small offspring.
The offspring are relatively self-sufficient at birth, and they don't get a lot of resources or parental care.
Plants such as the dandelion are included.
The two extreme strategies are at different ends of the continuum.
Life history strategies do not need to evolve as suites, but can evolve independently of each other, so each species may have some characteristics that trend toward one extreme or the other.

Humans are capable of altering their environment.
The stream environment where the dams are built is changed by them.
Humans have the ability to change their environment to increase their carrying capacity.

Some worry about the ability of Earth's environment to sustain its human population due to the rapid growth of Earth's human population.

The potential risks of famine, disease, and large-scale death are among the consequences of long-term exponential growth.

Human technology and our use of fossil fuels have caused unprecedented changes to Earth's environment, altering it to the point where some may be in danger of collapse.

The time it takes to add a certain number of humans to the population is shortening because of the growth rate.

The growth rate will likely decrease in the coming decades.
The population will continue to increase and the threat of overpopulation remains because of the damage done to the environment.

Over time, the time between the addition of each billion humans to Earth decreases.

The ability is responsible for human population growth because it resets the carrying capacity.
Human intelligence, society, and communication are all related to this ability.
Humans have developed agriculture and domesticated animals to increase their food supplies.
Humans use language to communicate with new generations, allowing them to improve upon previous accomplishments.

migration and public health are some of the factors that affect population growth.

Humans originated in Africa, but have since migrated to nearly all of Earth, increasing the area that we have colonized.
Public health, Sanitation, and the use of antibiotics and vaccines have reduced the ability of infectious disease to limit human population growth in developed countries.
Between 30 and 60 percent of Europe's population were killed by diseases such as the bubonic plaque in the 14th century, which reduced the world population by as many as one hundred million people.

Life expectancy in sub-Saharan Africa, which was increasing from 1950 to 1990, began to decline after 1985 due to HIV/AIDS mortality.

The technological advances of the industrial age have led to the reduction of the death rate in humans in the past 200 years, as well as the exploitation of the energy in fossil fuels.

Fossil fuels increase the resources available for human population growth through agriculture and harvesting wild populations.

The ability to associate population growth with the level of economic development in a region is a result of models that incorporate age structure.
The countries with rapid growth have a pyramidal shape in their age structure diagrams, showing a lot of younger individuals, many of whom are of reproductive age.
A pyramidal structure still exists in areas with slow growth, but with fewer young and reproductive-aged individuals and a greater proportion of older individuals.
Italy has no population growth.
Middle-aged and older individuals make up a greater percentage of these populations.
The countries with the highest growth rates are in Africa and Asia.

The diagram shows that the number of individuals decreases with age.
Stable population diagrams show that the number of individuals per age group decreases gradually, and then increases for the older part of the population.

Stages 1 through 3 show age structure diagrams for rapidly growing, slow growing, and stable populations.

Hundreds of millions of people will starve to death in the 1970s, even if crash programs are implemented now.

The laws of exponential population growth are still in effect and can't continue indefinitely.

Many Chinese couples have more than one child because they wish to have a male heir.

The effectiveness of the policy in limiting population growth is controversial.
Some of the more rural areas of the country have had stories of female infanticide.

In other countries, family planning education programs have had positive effects on population growth and standards of living.

The human population continues to grow despite population control policies.
Inequalities in access to food and other resources will continue to widen because of the need to produce more food to feed our population.
According to the United Nations, the world's population could vary from 6 billion to 6 billion.