Evolutionary Psych 3100
Lecture 3: Levels of Analysis
Jan 14 2014
WHY DOES THE DOOR OPEN? (motion sensor automatic doors)
- Sensor that senses photons moving, triggers electrical response and moves
- Other answer: it opens to let customers in…
- If there’s 2 answers, one has to be wrong, so which is wrong?... but neither are
- Addressing different aspects of the question: why does the door open and how does the
o HOW= MECHANISM
o WHY= FUNCTION
WHY DOES THE HEART BEAT?
- To pump blood (function – ‘the reason’)
- Signal that sends a neural electric signal that causes contractions (mechanism)
- What would happen if we tried to study the heart knowing only the mechanism but not
the function (the why)?
WHY DO WE EAT?
- To give us nutrients which give us strength (function)
- Empty stomach sends signal to brain = emotional sensation = I’m hungry (mechanism)
o Some of our food desires/preferences are hardwired (ex. Sweets, fats)
o Psychological adaptation: connection between taste buds and the brain
o Brain is set up to like and dislike things that will keep us alive; natural selection
(ex. The dung beetles brain is set up to enjoy feces, as it will help them
o Sexual interaction and social interactions are enjoyable as it benefits us;
reproduction and not being isolated
*we follow proximate motives – such as the mechanism, we are not necessarily consciously
seeking that function; we are not necessarily concerned with reproductive success when we
search for a mate, we just do things that are statistically associated with reproductive success
*our psychological mechanisms have developed in a way that is statistically associated to
reproductive success; meaning on average we do things that are linked to such results
Timbergen’s 4 Types of Questions/ Levels of Analysis
Proximate Causes Ultimate Causes
Mechanism: direct physiological, Function: what effect does it have on
cognitive, neurological, etc., causes of reproductive success?
behaviour at that time Why have that mechanism? Why did it
evolve? What causes it to persist rather
than being selected out?
Development of that Mechanism Phylogeny (evolutionary history): What
(ontogeny): processes that cause a did that trait evolve from? When in our
mechanism to develop within an lineage?
BEHAVIOUR OF BREASTFEEDING Mechanism
- specific hormones that cause milk production, neurological pathway that processes how
infant cries-> distress -> desire to nurture -> actual breastfeeding behaviour
- begins with birth -> cascade of hormones -> create multiple effects such as stimulation
of mammary glands, rewire the brain so that the mother is concerned for her child ->
learning of ‘how to’ and its importance. Something happens within a woman’s life history
to understand the benefits.
- provide nutrients to infant… survival
- evolved out of some parental investment and arose in an early mammalian ancestor,
millions of years ago
- we have the capacity to breastfeed because we are mammals, that’s what it means to
be a mammal (this is not an alternative to why it exists though, the function answer
above and mechanistic are both also correct)
‘Johnny helping Suzie’
- concern vs. feels good about helping vs. felt guilty about not helping (all going on in
Johnny’s brain at the time of helping vs. not helping… triggering the behaviour at