The Living World Question 6
Question: Assertion : From evolutionary point of view, human gestation period is believed to be shortening. Reason : One major evolutionary trend in humans has been the larger head undergoing relatively faster growth rate in the foetal stage. [AIIMS 2004]
Options:
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
Show Answer
Answer:
Correct Answer: D
Solution:
As the humans would require more gestation period (should have been 21 months as compared to 9 months and will increase).
Similarly the head size is increasing (especially the frontal brain) hence growth rate needs to increase but surprisingly most of the brain growth occurs after birth till 2 years (when the arterior fontanellae close at 18 months) and some more till 30 years when finally the cranial sutures close.
Thus an increase in brain/skull size would required increase in gestation period.
BETA
