Modern humans originated in central Africa, and because of this, human populations in this region have:
A) Limited genetic diversity because of stabilising selection
B) High genetic diversity because a relatively large population has persisted for a long time
C) Limited genetic diversity because of many population bottlenecks
D) Limited genetic diversity because of genetic drift
The correct answer and explanation is:
The correct answer is B) High genetic diversity because a relatively large population has persisted for a long time.
Human populations in central Africa are considered to have high genetic diversity due to several factors. First, central Africa is believed to be the cradle of modern human evolution, where Homo sapiens first appeared around 200,000 to 300,000 years ago. Because human populations in this region have been continuous for a long period, there has been more time for genetic variation to accumulate. This long history of persistence allows for a larger gene pool and greater diversity in traits.
High genetic diversity within a population occurs when the population size is relatively large and stable, which helps prevent genetic drift from reducing variation. In contrast, smaller populations are more susceptible to genetic drift, where random changes in gene frequencies can lead to the loss of certain genetic traits over time. The large, long-standing populations in central Africa have allowed for more genetic exchange and the maintenance of diverse traits within the population.
Furthermore, central Africa’s complex geography, with its varied environments, has also contributed to the diversity of human populations by creating different selective pressures in different regions. As a result, these populations have adapted in unique ways to their environments, further increasing genetic diversity.
In summary, the high genetic diversity in central African populations is primarily due to the long duration of human presence in the region and the large, continuous populations, which have allowed for the accumulation and maintenance of a broad range of genetic variation.