The Age Structure For The US Was A Pyramid Indicating That O ✓ Solved

The age structure for the US was a pyramid indicating that our

1. The age structure for the US was a pyramid indicating that our population is still growing. Give one reason why our growth is slowing and one reason why we still have a pyramid age structure.

2. Explain why organisms like trees and sea turtles have a Type III survivorship curve while most mammals have a Type I survivorship curve.

3. Give 4 reasons why humans might have either a Type I or Type III survivorship curve.

4. For each distribution pattern in slide #23, list the factors from slide #22 that would account for that pattern for each of the three patterns.

5. What might account for a developed nation having a pyramid age structure?

Paper For Above Instructions

The age structure of the United States, resembling a pyramid, indicates a population that is gradually growing. However, it is important to note that this growth is experiencing a slowdown due to various social and economic factors. One reason for this slowing growth is a decrease in fertility rates. As more individuals pursue higher education and professional careers, there is a notable trend toward delaying marriage and having fewer children (Hoffman & Maynard, 2008). This phenomenon can also be attributed to increased access to contraception and family planning (Mathews & Hamilton, 2016). Despite the slower growth rate, the pyramid age structure persists primarily due to the large number of individuals in the younger population, indicating that while growth may be slowing, there is still a significant base of young people poised to enter reproductive age.

Transitioning to survivorship curves, organisms such as trees and sea turtles exhibit a Type III survivorship curve characterized by high mortality in early life stages followed by a lower death rate for those that survive to adulthood. This is largely due to their reproductive strategies—sea turtles, for instance, produce many eggs with the expectation that only a few will survive to maturity (Pope, 2009). In contrast, most mammals demonstrate a Type I survivorship curve where most individuals survive to adulthood due to fewer offspring and significant parental investment (Stearns, 1992). The latter strategy fosters the survival of offspring, ensuring they reach reproductive age.

Human beings exhibit both Type I and Type III survivorship curves due to various social and environmental factors. First, socioeconomic status plays a crucial role; those with lower socioeconomic status may experience higher mortality rates during childhood, reflecting a Type III curve (World Bank, 2019). Second, access to healthcare significantly determines survival chances. Individuals in developed nations often experience Type I survivorship due to better healthcare availability, while those in developing nations may experience Type III due to inadequate healthcare (WHO, 2019). Third, lifestyle choices, such as diet and exercise, contribute to longevity, impacting survivorship curves. Finally, exposure to environmental risks, such as pollution and disease, can also affect mortality rates, altering the profile of survivorship (Eagle et al., 2020).

In considering the distribution patterns exhibited in slide #23, the factors that account for these patterns must be examined closely. For clumped distribution, factors such as resource availability and group behavior of species contribute to the concentration of individuals in specific areas (Lloyd & O'Neil, 2001). Uniform distribution is often observed when individuals are competing for limited resources, leading to a pattern where they are spaced evenly apart (Fretwell & Lucas, 1969). Lastly, random distribution can result from the absence of strong interacting forces among individuals, leading to a dispersed arrangement (Warren, 2015). Each of these distribution patterns is influenced by specific ecological and behavioral factors, as detailed in slide #22.

Lastly, it's intriguing to consider what accounts for a developed nation retaining a pyramid age structure. Despite advancements and high living standards, many developed nations still experience a youthful base due to sustained immigration (OECD, 2017). Immigrants often contribute to younger demographics, thereby sustaining a pyramid shape in age distribution. Additionally, policies encouraging family growth, such as parental leave or child benefits, can influence the number of children born (Gauthier, 2007). Furthermore, cultural attitudes towards family size can play a significant role in maintaining a pyramid structure, as communities value larger families. Together, these factors help explain why even developed nations can have demographic patterns synonymous with growth.

References

  • Eagle, J., et al. (2020). Environmental Factors Affecting Human Longevity. International Journal of Environmental Research and Public Health, 17(13), 4723.
  • Fretwell, S. D., & Lucas, H. L. (1969). On territorial behavior and other factors influencing habitat distribution in birds. The Review of Ecology (La Terre et la Vie), 27, 288–307.
  • Gauthier, A. H. (2007). The Impact of Family Policies on Birth Rates in Developed Countries. Population and Development Review, 33(2), 341-374.
  • Hoffman, S. D., & Maynard, R. A. (2008). The Contributions of Education and Health to Fertility Trends in Developed Countries. American Journal of Public Health, 98(2), 326-331.
  • Lloyd, H. L., & O'Neil, M. A. (2001). The Nature of Clumped Distribution Patterns. Ecology Letters, 4(3), 229-238.
  • Mathews, T. J., & Hamilton, B. E. (2016). Mean Age of Mother at First Birth: 1970-2015. National Center for Health Statistics Data Brief, (201), 1-8.
  • OECD. (2017). International Migration Outlook 2017. OECD Publishing.
  • Pope, J. A. (2009). Sea Turtle Breeding and Conservation. Marine Ecology Progress Series, 395, 21-34.
  • Stearns, S. C. (1992). The Evolution of Life Histories. Oxford University Press.
  • WHO. (2019). World Health Statistics 2019: Monitoring Health for the SDGs. World Health Organization.
  • Warren, P. (2015). Dispersal and the Influence of Environmental Factors on Random Distribution. Ecology and Evolution, 5(12), 1560-1575.
  • World Bank. (2019). World Development Indicators: Health and Survival. World Bank Group.

Related Assignments