doubtingthomas wrote: ↑Mon May 02, 2022 4:36 am
Thank you for your contributions Res Ipsa, very thoughtful.
Res Ipsa wrote: ↑Mon May 02, 2022 1:42 am
The papers refer to a body of evidence that appears to show that environment affects the rate of change for those portions of the brain. They use the term maturation to refer to the changes over time.
Res Ipsa wrote: ↑Mon May 02, 2022 1:42 am
The one effect that seems to be accepted is that certain environments tend to result in reaching puberty at an earlier age. I haven’t looked at those studies, so I don’t know anything about the evidence or the magnitude of the observed effect.
I understand, but wouldn't you expect them to have the prefrontal cortex fully developed before age 25? Or does it always have to be the average of 25?
Which "them?"
Without knowing the distribution of the data, I can't answer your question. If the average of one group is lower than the average a second, it does not mean that every single member of the group is lower than every single member of the other. It all depends on how the data is distributed.
Based on what we know, brain development is extremely complicated. This article illustrates the complexity of the process during adolescence.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3621648/ In general, the pre-frontal cortex develops last, so the completion of the changes in this area of the brain are considered the time at which the brain is fully mature.
Go back to this article:
https://www.nature.com/articles/s41598-018-27439-5
Notice that, according to this study, one type of stress increases the rate of change and another decreases the rate of change. Both changes show up during adolescence. None of them are tied to the date that brain maturation is completed. So, how do these contrary effects interact? Does one predominate over the other? Do they cancel out? Does living in a poor neighborhood correlate with one type of stress more than it does with the other?
Look back at the first article and note all the different things that affect brain development:
Adolescence is the developmental epoch during which children become adults – intellectually, physically, hormonally, and socially. Adolescence is a tumultuous time, full of changes and transformations. The pubertal transition to adulthood involves both gonadal and behavioral maturation. Magnetic resonance imaging studies have discovered that myelinogenesis, required for proper insulation and efficient neurocybernetics, continues from childhood and the brain’s region-specific neurocircuitry remains structurally and functionally vulnerable to impulsive sex, food, and sleep habits. The maturation of the adolescent brain is also influenced by heredity, environment, and sex hormones (estrogen, progesterone, and testosterone), which play a crucial role in myelination. Furthermore, glutamatergic neurotransmission predominates, whereas gamma-aminobutyric acid neurotransmission remains under construction, and this might be responsible for immature and impulsive behavior and neurobehavioral excitement during adolescent life. The adolescent population is highly vulnerable to driving under the influence of alcohol and social maladjustments due to an immature limbic system and prefrontal cortex. Synaptic plasticity and the release of neurotransmitters may also be influenced by environmental neurotoxins and drugs of abuse including cigarettes, caffeine, and alcohol during adolescence. Adolescents may become involved with offensive crimes, irresponsible behavior, unprotected sex, juvenile courts, or even prison. According to a report by the Centers for Disease Control and Prevention, the major cause of death among the teenage population is due to injury and violence related to sex and substance abuse. Prenatal neglect, cigarette smoking, and alcohol consumption may also significantly impact maturation of the adolescent brain. Pharmacological interventions to regulate adolescent behavior have been attempted with limited success. Since several factors, including age, sex, disease, nutritional status, and substance abuse have a significant impact on the maturation of the adolescent brain, we have highlighted the influence of these clinically significant and socially important aspects in this report.
How does living in a poor neighborhood correlate with each of these factors? What effect does each have on the rate of change. What effect do they have on the maturity level of the person when all brain changes are finished?
You don't know. I don't know. Science doesn't know. Given the state of the data, you have absolutely no idea how all the effects of living in a poor neighborhood affect the average age at which brain development is complete. Not only that, you have no idea what the impacts are on behavioral measures of maturity when brain development is complete. Suppose the average completion of the brain maturation process is complete, on average, at age 22 as opposed to age 25, but because of reduced period of time for brain maturity takes place, the average individual exhibits the "maturity" of an 18 year old in terms of risk taking, decision making, etc. Yes, the process happened faster, but would it be accurate to say that, in behavioral terms, people who live in poor neighborhoods "mature" faster? Hell no.
The only honest answer to your question is "I have no idea and neither do you."
Res Ipsa wrote: ↑Mon May 02, 2022 1:42 am
And you are again conflating the notion of a mature person with changes in the physical structure of the brain.
doubtingthomas wrote:How do you define "mature"?
I have no need to define it, as my argument depends only that you are using the term to mean something different than the papers you are citing do. You were the one making a claim about a link between maturity and growing up in a poor neighborhood. As you were talking about the maturity of a person and not changes in the brain, I assumed you were talking about the extent to which an individual's reasoning, emotional regulation, behavior, etc. resemble those of a typical adult, in constrast with those of a child or adolescent.
Res Ipsa wrote: ↑Mon May 02, 2022 1:42 am
Specifically, I’ve said nothing about the one paper because your link is to an abstract of a study that is being a paywall.
If all you did was take a quick look at this paper, then it is extremely likely you didn't understand what it was saying. This paper is not a study of any kind. It doesn't add any new evidence. It proposes a new theory that purports to explain how and why poverty is associated with certain behaviors of adolescents that had been described as detrimental in the literature. It argues that this theory is "consistent" with existing evidence, but fully admits that existing theories are consistent with existing evidence. The theory is that this behavior thought of as detrimental is actually a reproductive strategy driven by evolution.
This field -- originally referred to as sociobiology but I think more modernly as evolutionary psychology is quite controversial. It was once described by Steven J. Gould as the creation of "evolutionary just so stories." The age of this paper -- over 30 years -- puts it squarely in the period of time where papers the created these just so stories were being pumped out. Here's an article written for lay folks that discusses the problems with these kinds of papers.
https://www.newyorker.com/magazine/2012 ... ssarily-so
The problem is that it's possible to figure out a story for why every example of human behavior can be explained, in retrospect, as being part of a reproductive strategy. But evolutionary theory itself doesn't predict that every trait of an organism will have a beneficial effect in terms of passing on its genetic material. The problem for evolutionary psychology is that there is no good way to distinguish between a trait that is beneficial in an evolutionary sense, is neutral in an evolutionary sense, or detrimental but linked to a beneficial trait. I think of it as comparable to data mining to find patterns -- because it's always possible to find patterns in random data, how can one tell whether a pattern has some significance or is due to random chance.
This paper hypothesis a chain of causation that links various studies together to form the explanation. It's pretty damn complicated, as is the underlying theory which has to do with how an individual allocates their available energy resources to different activities.
But the two key parts of the analysis are predictions are (1) early puberty and (2) risky behavior that increases the likelihood of pregnancy. Once those key parts are understood, it's crystal clear that the references to "maturity" in the paper refer to the timing of puberty. That's all. The paper does not argue that the girls mature faster in terms of adult cognition, behavior, etc. Instead, they argue that the girls are more likely to engage in more extreme and risky behavior that increases the chances they will get pregnant.
So, the paper does not support your claim that girls who grow up in poor neighborhoods grow up faster. Rather, it predicts more extreme versions of what we would describe as "immature" behavior.
Again, if you just grab snippets out of scientific paper without taking the time to make sure that you understand what you are reading, you're odds of reaching a conclusion supported by the paper are vanishingly small. One good rule of thumb -- if the subject of the paper isn't the conclusion you are trying to draw, you have to be very careful. If the paper isn't trying to answer the question you are asking, you're likely to misunderstand what it is saying.
Res Ipsa wrote: ↑Mon May 02, 2022 1:42 am
You are simply injecting something you appear to want to be true into these studies.
No, because the literature says both genetics and environment play a role. I read your source, which gives the extreme ends of the ranges but doesn't give us any information about the actual distribution. Given the width of the entire range, one consequence may be that, whatever the average difference is, there may be a substantial overlap between the two distributions. Regardless of differences in the averages, there still may be a substantial number of girls who live in poor neighborhoods that complete the process of brain development before other girls.