With reference to Indian elephants, consider the following statements: 1. The leader of an elephant group is a female. 2. The maximum gestation period can be 22 months. 3. An elephant can normally go on calving till the age of 40 years only. 4. Among the States in India, the highest elephant population is in Kerala. Which of the statements given above is/are correct?

Let's analyze the statements concerning Indian elephants:

1. The leader of an elephant group is a female. This statement is correct. Elephant herds, especially of Asian elephants, are matriarchal societies. The herd is typically led by the oldest and most experienced female, known as the matriarch, who guides the group to food, water, and safety.

2. The maximum gestation period can be 22 months. This statement is correct. Elephants have one of the longest gestation periods among mammals, typically ranging from 18 to 22 months, with 22 months being a common maximum for a full-term pregnancy.

3. An elephant can normally go on calving till the age of 40 years only. This statement is incorrect. While their reproductive rates may decline with age, female elephants can continue to calve well beyond 40 years, often into their 50s and sometimes even early 60s, though pregnancies become less frequent. The 'only' makes the statement restrictive and incorrect.

4. Among the States in India, the highest elephant population is in Kerala. This statement is incorrect. According to recent elephant censuses in India, Karnataka consistently holds the highest elephant population, followed by Assam. Kerala is an important habitat but does not have the highest population.

Therefore, statements 1 and 2 are correct.