Week 2 Flashcards
(45 cards)
Define canalization
The tendency of a trait to remain stable despite how a person’s genes or environment may be reacting
A “typical” pattern of growth in a trait among most humans is an example of…
Canalization of that trait
A highly canalized trait is likely to have a lot of constraints coming from…
Genetics
Define phenotypic plasticity
The ability of a genotype to produce various phenotypes which may confer environmental adaptation
Muscle mass and fat mass are good examples of traits which are highly (canalized/plastic)
Plastic
Plasticity has its most marked effects in these stages of life
Infancy to adolescence
Why are the adult and post-reproductive life periods less plastic than other life periods?
During these periods we are not growing very much
What are 3 methods by which humans are able to adapt to their environment?
Culture and technology
Physiology and development
Genetic adaptation
Humans are most reliant on (1) to mediate environmental stresses
Culture and technology and physiology (as opposed to genetics)
What likely drove the evolution of a very flexible life cycle observed in humans?
An unpredictable environment
Periods of time which can have the most drastic impacts on human growth and development are called…
Critical windows
When is a human considered to be the most vulnerable to its environment?
The first 1000 days
What is hyperplasic growth?
A period in time where cells are growing in number (rapid division) - structure and function of cells are being established
What is hypertrophic growth?
Follows hyperplasic growth, cells increase in size
At what point is the physiology of your cells “locked in”?
In early childhood after hyperplasic growth
Why are critical developmental windows so short?
Because we want to set them up when the environment is stable, and the longer the window is the less chance there is of the environment remaining stable
How do humans ensure our babies are sheltered from a variable environment?
The baby’s nutrition is provided by the mother, who is able to buffer the environmental conditions for the baby
What “environment” is a human baby exposed to in its first 1000 days?
The mom: placenta and breastmilk
What is transient gestational diabetes?
Giving energy to a baby may increase the mom’s insulin signals - high levels of insulin may cause transient resistance while this is happening and usually goes away after birth = gestational diabetes
Why does the end of the critical window coincide with weaning?
By the time you’re weaned you are exposed to the environment, don’t want to be super sensitive to it at this point
How does a mom signal her phenotype/nutritional status to her baby in utero?
- Nutrients in the blood
- Hormones
- Cytokines and immune signals
- Metabolites (like glucose)
How is a mom able to signal stress to her baby if cortisol cannot cross the placenta?
Cortisol affects testosterone secretion (among other hormones) which are able to cross the placenta
In a study on stress and colony density, female seals who were in dense colonies tended to be (less/more) stressed than seals in less dense colonies
More - crowding = stressed
In seals, increased prenatal testosterone (due to stress) influenced these three qualities:
- Locomotor activity
- Growth
- Increased Competitiveness
