Passage

Natural selection cannot anticipate future environments on the earth. Therefore, the set of existing organisms can never be fully prepared for environmental catastrophes that await life. An outcome of this is the extinction of those species which cannot overcome environmental adversity. This failure to survive, in modern terms, can be attributed to the genomes which are unable to withstand geological vagaries or biological mishaps (infections, diseases and so on). In biological evolution on the earth, extinction of species has been a major feature. The earth may presently have up to ten million species, yet more than 90% of species that have ever lived on the earth are now extinct. Once again, the creationist doctrines fail to satisfactorily address why a divine creator will firstly bother to create millions of species and then allow them to perish. The Darwinian explanation for extinct life is once again simple, elegant and at once convincing—organisms go extinct as a function of environmental or biological assaults for which their inheritance deems them ill-equipped. Therefore, the so-called Darwinian theory of evolution is not a theory at all. Evolution happens—this is a fact. The mechanism of evolution (Darwin proposed natural selection) is amply supported by scientific data. Indeed, to date no single zoological, botanical, geological, paleontological, genetic or physical evidence has refuted either of the central two main Darwinian ideas. If religion is not taken into consideration, Darwinian laws are acceptable just like the laws proposed by Copernicus, Galileo, Newton and Einstein—sets of natural laws that explain natural phenomena in the universe.

With reference to the passage, the following assumptions have been made : 1. Only species that have the ability to overcome environmental catastrophes will survive and perpetuate. 2. More than 90% of the species on the earth are in the danger of getting extinct due to drastic changes in the environment. 3. Darwin's theory explains all the natural phenomena. Which of the above assumptions is/are valid?

(a) 1 only ✓ UPSC's answer
(b) 1 and 2 only
(c) 3 only
(d) 1, 2 and 3

Why the answer is (a)

• Assumption 1 is valid because the passage states that extinction occurs for species that 'cannot overcome environmental adversity' and that survival depends on genomes able to withstand such vagaries.

• Assumption 2 is invalid because the passage notes that more than 90% of species that have *ever lived* are now extinct, not that 90% of *current* species are in danger of extinction.

• Assumption 3 is invalid because the passage compares Darwinian laws to those of Copernicus, Galileo, Newton, and Einstein, which explain specific natural phenomena, not *all* natural phenomena.

• Therefore, only Assumption 1 is supported by the text, making option (a) the correct answer.

Why the other options are wrong

(b) 1 and 2 only: Assumption 2 incorrectly interprets the statistic about historical extinction rates as a current threat to 90% of existing species.
(c) 3 only: Assumption 3 is incorrect because the passage does not claim Darwin's theory explains all natural phenomena, only that it is a set of natural laws like those of other scientists.
(d) 1, 2 and 3: Assumptions 2 and 3 are invalid for the reasons stated above, so the combination is incorrect.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.