Chapter 3: Foundations of Development Flashcards
Define pleiotropy.
“The phenomenon of a single gene having effects on more than one phenotypic trait.”
We discuss the concept of niche selection in a later chapter. How does this concept relate to twins?
“Siblings, including twins, may have psychological adaptations designed to steer them toward different specializations, or niches, in order to reduce direct competition between them in their local environment.”
When do limbs, the circulatory system, and a few basic organs develop prenatally?
Eight weeks.
If a bottleneck occurs in a population then what would be the result?
Less genetic diversity.
Provide the three discussed milestones for fine motor development.
1 month: Pre-reaching 4 months: Bi-manual grasping. 9 to 10 months: Uni-manual grasping.
Why might an infant be preterm? What does this mean for their development?
Typically caused by multiple births, poor nutrition, smoking, and physical stress. Often results in oxygen deprivation due to under-developed lungs, which increases an infants likelihood of developing cerebral palsy plus visual and cognitive impairments.
When does neuronal differentiation begin and end?
Begins at roughly 20 weeks and continues for years after.
At what age can an infant technically survive on its own outside of the amniotic sac?
Twenty-eight weeks.
At the ages three and six, respectively, how much of the infants brain has developed?
Three: 80% Six: 90%
What is interesting about the varied development of synaptogenesis in different areas of the brain?
Synaptic density peaks at one year in the visual cortex, but not until four years in the prefrontal cortex. This shows the prioritization of various systems at different ages.
How does synaptic pruning operate?
It functions from one year into early adolescence to prune non-useful synaptic connections at a rate of 100,000 synapses per second.
What are some of the evolved cognitive adaptations of pregnant females?
1) They are better able to remember male faces, given the risk that an unknown male would have posed. 2) They are more selective when interacting with strangers, and tend to judge ill strangers harsher. 3) They will bunker down in their third trimester and become a home body, as per their nesting instinct.
Describe the life outcomes of children produced through in vitro fertilization (IVF) versus those conceived through more typical means.
Children produced through IVF had better life outcomes at age six, and more typical life outcomes at age twelve. Overall, the results of this procedure are not significantly different from that of typical copulation.
Provide the date at which each of these infant reflexes disappear: moro, rooting, sucking, and babinski.
Moro: three months. Rooting & Sucking: six months. Babinski: one month.
Describe the evolved utitlity of morning sickness.
Morning sickness evolved as a defence against teratogens (toxins). Particularly prevalent during the embryonic stage (three to eight months) when the embryo first joins with the mothers blood stream via the placenta.
What does it mean to say that children are “niche pickers”? How does this occur?
Children either inadvertently or purposefully place themselves in specific environments. Young children do this through an ‘evocative gene-environment’ relationship, where they evoke change in their environment through reactions. Older children do this through an ‘active gene-environment’ relationship, where they locate themselves in selected situations.
When does neuronal migration begin and end?
“By the age of 3 months, the brain has divided into three specialized divisions that will later underlie specific cognitive processes.” “…cell migration is complete by 7 months of gestation”
What does a ‘Cephalopelvic disproportion’ refer to? How might this have impacted our development through history?
“Refers to a situation where the baby’s head is too large to pass through the mother’s pelvis.” “The relationship between the mother’s pelvis and the fetus’s skull is a major determinant of human gestational age.” Humans are born nine months earlier than when we would otherwise expect—based upon other primates.
How many weeks does the prenatal period last?
Roughly 38 weeks.
What does genetic drift refer to?
The change in gene frequency that results from the fact that genes passed from parent to offspring are selected randomly, not evenly.
Which side of the brain do infants process speech with?
The left side.
In which group will we see lyonization expression?
Females, due to their dual X chromosomes.
Why is ‘Pre-Eclampsia’ an interesting birth complication?
Pre-eclampsia is, “extremely high blood pressure that results from pregnancy, and it occurs late in pregnancy, usually after 32 weeks.” This is the result of an infant extracting too many nutrients from the mother using placental tissue, and is more common in cases where the father is not a longterm partner.
How heritable are mono and dizygotic twins?
Monozygotic twins are not at all heritable, and occur 1 in 285 births. Dizygotic twins are maternally heritable, and occur 1 in 85 births.
