Connection for AP® Courses
The methods used to look at animal population dynamics can also be used to look at the human populations. Like animals, humans are affected by abiotic and biotic factors. Unlike animals, humans have the ability to manipulate the factors affecting the growth of their population. As a result, additional factors come into play when studying human population dynamics. When studying projections of human population growth, ethical questions can also come to light.
Information presented and the examples highlighted in the section support concepts outlined in Big Idea 4 of the AP® Biology Curriculum Framework. The AP® Learning Objectives listed in the Curriculum Framework provide a transparent foundation for the AP® Biology course, an inquiry-based laboratory experience, instructional activities, and AP® exam questions. A learning objective merges required content with one or more of the seven science practices.
Big Idea 4 |
Biological systems interact, and these systems and their interactions possess complex properties. |
Enduring Understanding 4.A |
Interactions within biological systems lead to complex properties. |
Essential Knowledge
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4.A.6
Interactions among living systems and with their environment result in the movement of matter and energy.
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Science Practice |
1.4
The student can use representations and models to analyze situations or solve problems qualitatively and quantitatively.
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Science Practice |
4.1
The student is able to justify the selection of the kind of data needed to answer scientific questions about the interaction of populations within communities.
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Learning Objective |
4.11
The student is able to justify the selection of the kind of data needed to answer scientific questions about the interaction of populations within communities.
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Essential Knowledge
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4.A.6
Interactions among living systems and with their environment result in the movement of matter and energy.
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Science Practice |
2.2
The student can apply mathematical routines to quantities that describe natural phenomena.
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Learning Objective |
4.12
The student is able to apply mathematical routines to quantities that describe communities composed of populations of organisms that interact in complex ways.
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Essential Knowledge
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4.A.6
Interactions among living systems and with their environment result in the movement of matter and energy.
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Science Practice |
6.4
The student can make claims and predictions about natural phenomena based on scientific theories and models.
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Learning Objective |
4.13
The student is able to predict the effects of a change in the community’s populations on the community.
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Essential Knowledge
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4.A.6
Interactions among living systems and with their environment result in the movement of matter and energy.
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Science Practice |
6.4
The student can make claims and predictions about natural phenomena based on scientific theories and models.
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Learning Objective |
4.16
The student is able to predict the effects of a change of matter or energy availability on communities.
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Concepts of animal population dynamics can be applied to human population growth. Humans are not unique in their ability to alter their environment. For example, beaver dams alter the stream environment where they are built. Humans, however, have the ability to alter their environment to increase its carrying capacity sometimes to the detriment of other species (e.g., via artificial selection for crops that have a higher yield). Earth’s human population is growing rapidly, to the extent that some worry about the ability of the earth’s environment to sustain this population, as long-term exponential growth carries the potential risks of famine, disease, and large-scale death.
Although humans have increased the carrying capacity of their environment, the technologies used to achieve this transformation have caused unprecedented changes to Earth’s environment, altering ecosystems to the point where some may be in danger of collapse. The depletion of the ozone layer, erosion due to acid rain, and damage from global climate change are caused by human activities. The ultimate effect of these changes on our carrying capacity is unknown. As some point out, it is likely that the negative effects of increasing carrying capacity will outweigh the positive ones—the carrying capacity of the world for human beings might actually decrease.
The world’s human population is currently experiencing exponential growth even though human reproduction is far below its biotic potential (Figure 36.15). To reach its biotic potential, all females would have to become pregnant every nine months or so during their reproductive years. Also, resources would have to be such that the environment would support such growth. Neither of these two conditions exists. In spite of this fact, human population is still growing exponentially.
A consequence of exponential human population growth is the time that it takes to add a particular number of humans to the Earth is becoming shorter. Figure 36.16 shows that 123 years were necessary to add 1 billion humans in 1930, but it only took 24 years to add two billion people between 1975 and 1999. As already discussed, at some point it would appear that our ability to increase our carrying capacity indefinitely on a finite world is uncertain. Without new technological advances, the human growth rate has been predicted to slow in the coming decades. However, the population will still be increasing and the threat of overpopulation remains.
Link to Learning
Click through this interactive view of how human populations have changed over time.
Based on the interactive, how would you describe human population growth?
- a decline in human population growth
- a lag in human population growth
- logistic growth
- exponential growth