question_answer

We are told that evolution is a continuing phenomenon for all living things. Are humans also evolving? Justify your answer.

Or

(i) Explain the observations and the conclusion drawn by Darwin during his visit to Galapagos islands.

(ii) Write the two key concepts of Darwin's theory of evolution.

Answer:

New research suggests that despite modem technology and industrialisation, humans continue to evolve. In the last 10000 years or so, the pace of our evolution has speeded up 100 times, creating more mutations in our genes and hence, greater natural selection.

Some clues that show humans are evolving are as follows

(a) Lactose tolerance Historically, the gene that regulated human's ability to digest lactose was shut down as infants are weaned off of their mother's breast milk, However, adult human, in the regions of Africa and Northern Europe developed the ability to tolerate lactose in their diets as recent as 5000 or 6000 years ago due to mutations.

(b) Wisdom teeth Our ancestors had much bigger jaws than we have due to their eating habits. Today our jaws are much smaller and wisdom teeth are often impacted. Estimates say that the wisdom teeth will disappear in the coming human population.

Or

(i) Observations and conclusions drawn by Darwin Darwin during his visit to Galapagos islands found many varieties of finches in the same island. All the varieties evolved on the island itself. From the original seed - eating creatures many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches. This process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography or habitat is called adaptive radiation.

(ii) The two key concepts of Darwin's theory of evolution are as follows

(a) Branching descent, e.g. Darwin's finches.

(b) Natural selection This is based on the following observations

There are limited natural resources.

Populations are stable in size except for seasonal fluctuations.

Varying characteristics in members of population.

Variations are generally inherited.

Population size has two facts, i.e. theoretically it grows exponentially, but in reality, population size is limited due to the competition among the individuals for resources.