World Population Change over Time

In comparing rates between populations, it is important that one is comparing ‘like with like’. One population may be considerably older than a population to which it is compared and therefore it would not be surprising that mortality rates were higher. Instead it is more useful to make comparisons taking account of differences in characteristics such as age or gender. The same considerations apply to examining disease rates over time in a given population. If the characteristics of the population change over time (e.g. the population gets older), this needs to be considered. To formulate hypotheses, the rate of a disease under study in a population may be compared with the rate in other populations, or in the same population at difierent time points. If the rates vary significantly between populations or are changing within a population, then this provides impetus for investigating the reasons underlying these differences or changes.

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Analgesic use in a Norwegian general population: change over time and high-risk use - The Tromsø Study

BMC Pharmacology and Toxicology ◽

10.1186/s40360-015-0016-y ◽

2015 ◽

Vol 16 (1) ◽

Cited By ~ 16

Author(s):

Per-Jostein Samuelsen ◽

Lars Slørdal ◽

Ulla Dorte Mathisen ◽

Anne Elise Eggen

Keyword(s):

High Risk ◽

General Population ◽

Population Change ◽

Change Over Time ◽

Analgesic Use ◽

Over Time

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Pancake Evolution: A Novel & Engaging Illustration of Natural Selection

The American Biology Teacher ◽

10.1525/abt.2019.81.2.110 ◽

2019 ◽

Vol 81 (2) ◽

pp. 110-114 ◽

Cited By ~ 1

Author(s):

D. Andrew Crain ◽

Matthew Hale

Keyword(s):

Genetic Diversity ◽

Natural Selection ◽

Second Generation ◽

Population Change ◽

Allelic Variation ◽

Postsecondary Students ◽

Change Over Time ◽

Changing Environments ◽

Over Time ◽

Made In

Understanding the theory of natural selection is crucial for any student of biology, but many secondary and postsecondary students struggle with the concepts. We present a novel, engaging exercise to illustrate natural selection through making pancakes. After students make pancakes (representing offspring) with various ingredients (illustrating genetic diversity and allelic variation), other students (representing the environment) judge the pancakes on the basis of taste. Only the highest-ranking pancakes are made in a second generation (illustrating population change over time), and new ingredients are added. After several generations of pancakes, with each generation exposed to ever-changing “environments,” students understand the fundamental concepts associated with the theory of natural selection.

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