Final answer:
A large base in a population pyramid typically indicates a high birth rate in society, reflecting a larger number of births compared to deaths. This scenario is often observed in developing or underdeveloped countries with youthful populations.
Step-by-step explanation:
A population pyramid represents the age-sex structure of a population. When a population pyramid shows a large base, this typically indicates a high birth rate. It reflects a youthful society with a large proportion of children and a reduced number of elderly individuals. In contrast, improved healthcare, especially in more developed countries, often results in an aging population, which is represented by a narrower base and a bulkier top of the pyramid, as it indicates fewer young people and a greater proportion of older individuals. Economic stability might lead to a more balanced distribution, while migration can cause significant changes in a population's concentration in different areas.
Considering the society represented by the pyramids with a broad base and tapered sides, it's likely experiencing a larger number of births compared to deaths. This can be attributed to high fertility rates and possibly higher mortality rates at older ages. Thus, a large base in the population pyramid is commonly associated with developing or underdeveloped countries where healthcare, sanitation, and economic conditions are still improving.