Why study non-human animals?
The theory of descent with modification predicts:
1. Where do neurons come from?
The buildingblocks of the nervous system, its neurons, are similarin all animalsthat have a
2. How did it get built?
a. The human nervous system isbuild int an organizedway and it is possibleto see stept by
step how that organization came about by examiningpredecessors?
3. The addition of more neurons isrelated to behavior becoming more complex.
Why do westudy these animals? What can we learnfrom animal research?
- Fruit fly
○ Chromosomeis related to genetic inheritance
○ Genes are on chromosomes
○ First genome
○ Understanding of Down's syndrome
Caused by Chromosome21, results in learning impairments,alzheimerlike
changes in the brain, earlierdeath, distinctive features
□ Why would adding one more chromosome make things bad?
Maybe it's just one gene?
◊ Put an extra chromosome in a fruit fly and observing
abnormalitiesin the fruit flyand manipulategene by gene and
discover what it isthat produces this disorder, you can do
genetic modificationsto stop it.
A widevariety of animalsare used to research, including humans.
- Fruit fly, Californiasea slug, zebra finches (complicated songs), miceand monkeys
○ Each one has a particular way of answering a question that a scientist wants to answer
1. The human brain is too complex
2. Understand the evolutionof the human brain
3. Understand animals
4. Model human diseases
5. Find relationshipsbetween brain structure and behavior.
Darwin's finches, natural selection
Darwin's pigeons, artificial selection
The neuron theory
- Santiago Ramon y Cajal
○ First person to describe a neuron
○ Nobel prizein 1906
- Cellshavevery distinctive features
○ Don't touch each other, communication
- Take these cellsand stain them (talked about later)
C Eleganshas 302 neurons of some 900 cells
- Take what you know about neurons and apply it to other animals
- Every animal that has muscles, nervous systems, etc, has a neuron that looks likeevery other
Human brain was 100 billionneurons
- How big is 100 billion?
○ The amount of trees in the Amazon 1. Neurons for every animal that has them, are pretty much the same.
a. Neurons and muscles seem to go together, that became duplicated until a complex brain
likeours was created
b. What werethe