Comprehension
When researchers at Emory University in Atlanta trained mice to fear the smell of almonds (by pairing it with electric shocks), they found, to their consternation, that both the children and grandchildren of these mice were spontaneously afraid of the same smell. That is not supposed to happen. Generations of schoolchildren have been taught that the inheritance of acquired characteristics is impossible. A mouse should not be born with something its parents have learned during their lifetimes, any more than a mouse that loses its tail in an accident should give birth to tailless mice. . . .
Modern evolutionary biology dates back to a synthesis that emerged around the 1940s-60s, which married Charles Darwin’s mechanism of natural selection with Gregor Mendel’s discoveries of how genes are inherited. The traditional, and still dominant, view is that adaptations – from the human brain to the peacock’s tail – are fully and satisfactorily explained by natural selection (and subsequent inheritance). Yet [new evidence] from genomics, epigenetics and developmental biology [indicates] that evolution is more complex than we once assumed. . . .
In his book On Human Nature (1978), the evolutionary biologist Edward O Wilson claimed that human culture is held on a genetic leash. The metaphor [needs revision]. . . . Imagine a dogwalker (the genes) struggling to retain control of a brawny mastiff (human culture). The pair’s trajectory (the pathway of evolution) reflects the outcome of the struggle. Now imagine the same dog-walker struggling with multiple dogs, on leashes of varied lengths, with each dog tugging in different directions. All these tugs represent the influence of developmental factors, including epigenetics, antibodies and hormones passed on by parents, as well as the ecological legacies and culture they bequeath. . . .
The received wisdom is that parental experiences can’t affect the characters of their offspring. Except they do. The way that genes are expressed to produce an organism’s phenotype – the actual characteristics it ends up with – is affected by chemicals that attach to them. Everything from diet to air pollution to parental behaviour can influence the addition or removal of these chemical marks, which switches genes on or off. Usually these so-called ‘epigenetic’ attachments are removed during the production of sperm and eggs cells, but it turns out that some escape the resetting process and are passed on to the next generation, along with the genes. This is known as ‘epigenetic inheritance’, and more and more studies are confirming that it really happens. Let’s return to the almond-fearing mice. The inheritance of an epigenetic mark transmitted in the sperm is what led the mice’s offspring to acquire an inherited fear. . . .
Epigenetics is only part of the story. Through culture and society, [humans and other animals] inherit knowledge and skills acquired by [their] parents. . . . All this complexity . . . points to an evolutionary process in which genomes (over hundreds to thousands of generations), epigenetic modifications and inherited cultural factors (over several, perhaps tens or hundreds of generations), and parental effects (over single-generation timespans) collectively inform how organisms adapt. These extra-genetic kinds of inheritance give organisms the flexibility to make rapid adjustments to environmental challenges, dragging genetic change in their wake – much like a rowdy pack of dogs.
Question: 1

The Emory University experiment with mice points to the inheritance of: 

Updated On: Jul 29, 2025
  • psychological markers

  • acquired characteristics 

  • personality traits
  • acquired parental fears
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The Correct Option is D

Solution and Explanation

The Emory University experiment with mice illustrates the phenomenon of acquired parental fears being passed down to subsequent generations. In the experiment, mice were conditioned to fear the smell of almonds through the use of electric shocks. Surprisingly, both the offspring and the grandchildren of these mice also exhibited fear towards the same smell, despite never having been subjected to the conditioning themselves. This finding challenges the traditional view that acquired characteristics are not inheritable.

The underlying explanation for this phenomenon is "epigenetic inheritance." This process involves chemical modifications to DNA that affect gene expression without changing the genetic code itself. These modifications, known as epigenetic marks, can sometimes escape the typical resetting process during the production of sperm and eggs, allowing them to be passed on to the next generation.

Therefore, the fear of almonds in the offspring of the original mice was not learned but inherited through an epigenetic mark transmitted in the sperm. This aligns with broader scientific perspectives indicating that parental experiences and environmental factors can indeed influence the gene expression of their progeny.

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Question: 2

Which of the following best describes the author's argument?

Updated On: Jul 29, 2025
  • Darwin’s and Mendel’s theories together best explain evolution.
  • Mendel’s theory of inheritance is unfairly underestimated in explaining evolution.
  • Wilson’s theory of evolution is scientifically superior to either Darwin’s or Mendel’s.
  • Darwin’s theory of natural selection cannot fully explain evolution.
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The Correct Option is A

Solution and Explanation

The author's argument is best described by the option: "Darwin’s and Mendel’s theories together best explain evolution." This argument arises from the passage's exploration of modern evolutionary biology. The passage details how the combined insights from Darwin’s natural selection and Mendel’s genetic inheritance form the foundation of evolutionary theory. However, the passage also acknowledges that evolution is now understood to be more complex, incorporating genomics, epigenetics, and developmental biology. The description of systems such as epigenetic inheritance supports the complexity beyond individual theories, suggesting a more comprehensive understanding where various factors collectively inform adaptation. This aligns with the synthesis of Darwin's and Mendel's ideas, indicating that their combination best explains evolution, acknowledging that additional elements enrich the picture.
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Question: 3

Which of the following, if found to be true, would negate the main message of the passage? 

Updated On: Jul 29, 2025

  • A study affirming the influence of socio-cultural markers on evolutionary processes. 

  • A study highlighting the criticality of epigenetic inheritance to evolution. 

  • A study indicating the primacy of ecological impact on human adaptation. 

  • A study affirming the sole influence of natural selection and inheritance on evolution.
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The Correct Option is D

Solution and Explanation

To determine which option negates the main message of the passage, we should identify the central theme of the passage, which is that evolution is more complex than previously thought, involving factors beyond just natural selection and inheritance. These factors include epigenetics and cultural inheritance, indicating that evolution is influenced by multiple extragenetic factors. The summary of key points is:
  • The inheritance of acquired traits through epigenetic marks and cultural influences contradicts the classical view that adaptations are solely a result of natural selection and genetic inheritance.
  • Epigenetics and cultural factors are shown to affect evolution, making it more nuanced and complex.
Given these points, the statement that negates the main message would be one that denies the complexity of evolution by affirming classical evolutionary theory.
The correct answer is: A study affirming the sole influence of natural selection and inheritance on evolution.
This option negates the main message because it contradicts the passage's argument for the involvement of multiple factors, such as epigenetics and culture, in evolution.
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Question: 4

The passage uses the metaphor of a dog walker to argue that evolutionary adaptation is most comprehensively understood as being determined by:

Updated On: Jul 29, 2025
  • extra genetic, genetic, epigenetic and genomic legacies.
  • socio-cultural, genetic, epigenetic, and genomic legacies
  • ecological, hormonal, extra genetic and genetic legacies.
  • genetic, epigenetic, developmental factors, and ecological legacies.
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The Correct Option is D

Solution and Explanation

The passage uses the metaphor of a dog walker to illustrate the complexity of evolutionary adaptation involving multiple factors. The central idea is that while traditional views emphasized genetic inheritance alone, modern evidence suggests a more multifaceted understanding, incorporating:
  • Genetic factors: Genes inherited following Mendelian principles.
  • Epigenetic factors: Chemical modifications affecting gene expression, which can be inherited (e.g., epigenetic marks).
  • Developmental factors: Influences from developmental biology, including molecules like hormones passed from parents.
  • Ecological legacies: Environmental and cultural influences shaping adaptation over generations.
The dog walker metaphor represents genes, and the dogs represent various factors tugging in different directions, contributing to the evolutionary pathway. This comprehensive understanding suggests that adaptation is not solely genetic but involves interactions between multiple legacies, leading to the correct answer: genetic, epigenetic, developmental factors, and ecological legacies.
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Question: 5

In the first paragraph, the author laments the fact that:

Updated On: Jul 29, 2025
  • there is no recognition of the Indian soldiers who served in the Second World War.
  • the new war memorial will be built right next to India Gate.
  • India lost thousands of human lives during the Second World War.
  • funds will be wasted on another war memorial when we already have the India Gate memorial.
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The Correct Option is A

Solution and Explanation

In analyzing the comprehension passage, it is clear that the primary focus is on the concept of inheritance of acquired characteristics, which was traditionally believed to be impossible, but is now being reconsidered due to new evidence. This evidence includes the phenomenon of epigenetic inheritance, where experiences can affect offspring characteristics.

The question pertains to what the author laments in the first paragraph. Let's examine the options:

  1. There is no recognition of the Indian soldiers who served in the Second World War.
  2. The new war memorial will be built right next to India Gate.
  3. India lost thousands of human lives during the Second World War.
  4. Funds will be wasted on another war memorial when we already have the India Gate memorial.

​The correct answer is: there is no recognition of the Indian soldiers who served in the Second World War.

This aligns with the mention of a lack of recognition for Indians who served in World War II, which is explicitly stated in the comprehension portion provided.

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