Chapter 6: Evolution of the Nervous System

Question 1

What contains all the genetic information of an organism?

Answer 1

The genome/genotype

Question 2

What is the difference between a genotype and a phenotype?

Answer 2

An organism’s observable characteristics make up its phenotype, while its genetic information that codes for that characteristic is a genotype.

Question 3

What influences a phenotype?

Answer 3

One’s genotype and environment through epigenetic influences.

Question 4

What are 2 steps of epigenetic changes we studied?

Answer 4

1) DNA Methylation

2) Histone modification

Question 5

Explain DNA Methylation and Histone Modification in Epigenetics

Answer 5

1) Methyl group, found in diet sometimes, tags DNA for gene activation or repression.
2) This then leads to Histone modification - it affects how tightly the DNA is wrapped around the histone. If it’s wrapped tightly, its harder to express the gene and if it’s not it’s easier.

Question 6

Human brains are the product of natural selection. true or false?

Answer 6

True

Question 7

What is Directional selection? (graph)

Answer 7

Selection that favors a shift in a characteristic within a population. (prefer brown over blue eyes)

Question 8

What is Stabilizing selection? (graph)

Answer 8

Selection that favors reduced variation in a characteristic within a population. (prefer only brown eyes)

Question 9

What is Disrruptive selection? (graph)

Answer 9

Selection that favors a divergence in a characteristic within a population. (prefer both brown and blue)

Question 10

Describe the 3 myths of evolution.

Answer 10

1) Naturalistic fallacy: the assumption that what ‘is’ is what is ‘good’
2) Nature vs Nurture: that theres competition between the two when in reality it’s a mixed influence.
3) Determinism fallacy: the assumption that what is rooted in genetics is unchangeable.

Question 11

What is Adaptive flexibility?

Answer 11

It’s a term that claims the brain is a physical system designed to adapt and change according to the environment.

Question 12

What are Spandrels in evolution?

Answer 12

A behavior/structure that is a by-product of an adaptive behavior/structure but is of no use now.

Question 13

What is an example of a Spandrel?

Answer 13

The belly button - from the umbilical chord.

Question 14

What do you call features that have adapted to perform a function that is not what it originally was supposed to adapt for?

Answer 14

Exaptations

Question 15

What is an example of an Exaptation?

Answer 15

Feathers - they were meant to retain body heat but instead birds use them to fly.

Question 16

What are Analogous features?

Answer 16

Structures between species that LOOK like they have common evolutionary origins but they DO NOT. (e.g. bee wing and bird wings)

Question 17

How do analogous features come about?

Answer 17

Through Convergent evolution.

Question 18

What is convergent evolution?

Answer 18

The evolution of a shape/structure in DIFFERENT ways to serve the SAME function.

Question 19

What are Homologous features?

Answer 19

Structures that ARE SIMILAR because they have COMMON evolutionary origin.

Question 20

What is divergent evolution?

Answer 20

the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure

Question 21

Identify 6 shared features among vertebrates.

Answer 21

1) Development from a Hollow Dorsal Neural Tube: The head of the embryonic neural tube goes on to form the major subdivisions of the brain, but a fluid series of hollow spaces within the brain—the ventricular system—persists into adulthood.
2) Bilateral symmetry
3) Segmentation of Spinal Nerves
4) Hierarchical control: Higher levels of the nervous system tend to control or modulate lower levels.
5) CNS and PNS separation
6) Functional specialization: Certain physiological and behavioral processes are controlled by specific neural mechanisms, often consisting of specific networks of brain regions operating together.

Question 22

Identify 3 evolutionary changes to the human brain.

Answer 22

1) Increase in size.
2) Increase in size mostly in Cerebrum
3) Increase in brain convolutions (gyri and sulci)

Question 23

What is the term used to describe when once evolved traits are no longer useful or are maladaptive due to changes in environment?

Answer 23

Evolutionary mismatch.