34. Physiologists’ approach to plant improvement

Intersecting Processes

There is

a longstanding tension within agricultural research between, broadly speaking, breeders and physiologists. Breeders seek improvement through selection of varieties combined with plant or animal husbandry appropriate to those varieties. Physiologists focus on determining and manipulating the specific genetic and environmental factors underlying the development of the trait in question. (In this era of genomics, breeders may also be physiologists, but let [us]continue distinguishing the two ideal types.) Breeders are not uninterested in the underlying factors. They make hypotheses about such factors based on… trials [of multiple varieties grown in multiple locations] as well as sources other than the data analysis, then use these hypotheses to plan the next set of varieties and locations on which to collect data… Physiologists make much less use of variety-location trials to generate hypotheses; instead they focus on experiments under controlled conditions. Since the advent of DNA technologies, their experiments have included…

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25. Congenital traits

Intersecting Processes

Some traits that one is born with may be associated with external factors during gestation, such as exposure to thalidomide.  Researchers may, however, in deciding which traits to investigate to look for genes, choose congenital traits in the knowledge that they have been formed without the social interactions or environmental influences that occur after birth.  Indeed, even when congenital traits are associated with external factors during gestation, investigating the epigenetic basis of the trait—the way it involves turning on or off a gene—may be fruitful.

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23. “All cancers are genetic”

Intersecting Processes

“All cancers are genetic,” the genetic oncologist might say.   If asked to elaborate, they might explain that “all cancers begin when one or more genes in a cell are mutated (changed), creating an abnormal protein or no protein at all” (cancer net).  If asked what that means for relatives, they would note that “only about 5% to 10% of all cancers result directly from gene defects… inherited from a parent” (American Cancer Society).

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21. Abnormal conditions provides insight about origin of normal conditions

Intersecting Processes

Five offspring of a couple in a remote area of Turkey grew up walking quadrupedally on their hands and feet, as portrayed in the popular science documentary ‘Family That Walks on All Fours.’ Among the various angles of research on the siblings was genetic analysis identifying a mutation in a gene on chromosome 17 influencing cerebellum development and the work of certain evolutionary biologists try to link this gene to the evolution of human bipedalism 3 million years ago.  Indeed, other deleterious effects of the gene are depicted as reversing the progress in fine motor coordination and intelligence that accompanied human evolution.

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20. If it is passed down, there’s nothing we can do (could have done)

Intersecting Processes

[C]onsider the results of the study of multiple twins while thinking about your own family. Consider a scenario in which the nonidentical twins are much less similar than identical twins, which means that sharing fewer genes makes a big difference (skipping here the technicalities of getting the number—heritability—that quantifies that result…). If this were the case, for whatever trait we are thinking about, e.g., IQ test score, we might say: “There is nothing I could do as a parent to change the outcome for my offspring. I am not to blame for the outcome other than having passed on my genes.” If that conclusion seems justified, we might then reason that the same is true for every other family, and thus society as a whole should not try to change what it is doing because it will not make a difference.

Complications

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7. To explain innate behaviors

Intersecting Processes

A behavior that is innate occurs without being learned.  As long as we can assume that the environment is sufficient for the organism to survive, this independence from learning might lead us to look for the genes that determine the trait.

Some complications: Behaviors still have to be developed—they are not evident in the fertilized egg!  Investigations of development show that behaviors that are fixed in normal circumstances can still be changed.  For example, as Anne Fausto-Sterling describes, an innate behavior of rat pups is to crawl to their mother’s teats after birth.  Experimental studies have shown, however, that if the mothers are fed peppermint while pregnant, the newborn rat pups crawl towards the peppermint taste even if that takes them away from their mothers.  We still have to explain the development of the innate behavior of pups crawling towards a taste that is familiar, but the experiment shows us the value of not simply…

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6. Genetic = hard to change

Intersecting Processes

A gene passed to you from a parent is in every cell of the body that develops.  If it has an effect on your traits, there is no way to expunge it from every cell in order to eliminate that effect.

One complication to this line of thinking is that the immutable gene, even when that gene has severe implications for the body, is insufficient to dictate the social implications for the person.  Someone I came to know with muscular dystrophy was, in the 1960s, what we now call mainstreamed at school at his mother’s insistence.  High school friends who went on to university with him initiated a pattern of what we now call independent living that continued as his physical condition required sleeping in an iron lung.  Meanwhile, he worked as a counsellor first for students then at centers for the disabled and became a parent, living decades beyond the expected 20 or so years…

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5. Entry points into study of development

Intersecting Processes

Since the late 1800s—well before advances in genetics and molecular biology—developmental biologists have been studying the mechanisms through which a single cell divides into multiple cell types and gets arranged into tissues, organs, and the organism’s overall form (Gilbert 2013).  Genetic knowledge and technologies [provide] a productive strategy to work towards teasing open the complexities of development.  (Extracted from p. 1-3 of Nature-Nurture? No).

The first complication of this reason to look for genes is really a clarification.

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4. Understand the basis of traits

Intersecting Processes

Since the rediscovery of Mendel’s laws, it has been common to talk about genes for xx, where xx could be feeblemindedness, IQ, sports ability, procrastination, homosexuality, divorce, crime, fidelity, conservatism, liberalism, schizophrenia,… (You choose xx; see what you get when yougoogle “Is there a gene for xx.”)

There are manycomplications, including

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