Introduction to Adaptations
The biological sciences, including psychology have a shared agenda: their goal its to
elucidate the adaptive designs of living things.
Adaptation = biological traits, or characteristics, that help an individual survive and
reporduce in its habitat. Adaptations perform a specific function that make an organism
better suited to its environment.
Examples: Eyes enable you to recognize and respond effectively to things around you
by detecting and analyzing the reflected light.
Raccoons primarily nocturnal and have good night vision, their front paws are so
sensitive they can "see" with them through touch as they scavenge for food.
Some bat species have evolved yet another adaptation that enables them to nagivate
through their environment at night (echolocation)
*Note: Adaptations are always for something; they serve identifiable functions in the life
of an indvidual.
Biological traits aren't semply morphological; perceptual processes and behaviours are
also biological adaptations.
Cognitive Psychologists study "higher" mental processes:
- Selective attention
- Memory encoding
- Memory retrieval
- Word recognition
These mental proceesses refer to tasks that the mind needs to accomplish to do its jobb.
In other words, they refer to the adaptive functions of mental acitivy. So cognitive
psychologists aer also adaptationists: they find it helpfl to analyse their subject matter
into adaptive their subject matter into adaptie problems or tasks, and to then look for the
adaptations that solve those problems.
There are many more adaptive functions that are served by our brain/minds. The
adaptive functions that are served by our minds evolved like all other adaptations -
through natural selection.
Evolution by Natural Selection
How do adaptations arise?
Adaptations emerge in development as a result of the activation of relevant genes in
interactionwith relavent aspects of the environment.
- How do they arise
- How do they become differentiated in related species
- How do they maintain their complex functionality in spite of the destruve force of
random genetic mutations
Ans: Natural Selection
Natural Selection Discovered by Charles Darwin and Alfred Russel Wallace
4 basic mechanisms of evolution;
a) Natural Selection
c) Genetic drift
Natural Selection = differential survival and reproduction of organisms as a result of the
heritable differences between them.
3 Essential Components:
1. Significant Individual Differences - Within any population, there is variation among
individuals for any given characteristic. Second, these differences affect individuals'
chances of surviving and reproducing (causing)..
2. Differential Reproduction - Some indviduals will have more offspring than others.
Lastly, the traits that give rise to differential reproduction have a genetic basis (meaning
3. Heritability - The offspring of successful reproducers will resemble their parents will
respect to these variable characteristics.
The blue fish are well camouglaged in the blue ocean water and the red fish are much
more visible to predators.
Therefore, the red fish get eaten more often and so, on average, the blue fish survive
and reproduce better than the red fish.
Blue fish tend to have blue coloured offspring because body coloure is a heritable trait.
-> Over successive generations, there will be selective transmission of heritable parental
traits and the population will be mostly blue. This is because the specific characteristics
that are best adapted for survival and reproduction are going to be reproduced at higher
rates. Eventually, tif the process continues, the entire fish population will be blue. Natural selection cannot act in a population where everyone is identical - variation
amongst the population is required.
Natural Selection in the Wild
Stabilizing Selection = Selection against any sort of departure from the species-typical
This sort of selection tends to keep traits stable over generations.
Example: Blue would remain the most common colour in our fish population bc it is
adaptive and minimizes the rish of predation. But in some cases (esp. if sig. change in
environ) then selection favours traits that are not typical and evolutionary change can be
observed, sometimes quite rapid evolutionary change.
"The Medium Ground-Finch" which lives on Daphne island in the Galapagos.
Peter and Rosemary Grant who studies these birds, along with their students, were able
to observe natural selection in action - within only a generation!
Beak size and ability to crack seeds: In 1977, a severe drought hit the island and
decimated the vegetation. Food was scarce adn all of the small seeds were quickly
eaten up, leaving only the large touch seeds that the finches usually didn't bother with.
The birds that had unusually big, heavy beaks, were able to eat the hard seeds that
remained and so survived the drought whereas the birds with small beaks died from
starvation. Between 1976 and 1978 the average beak depth increased from 9.4mm to
10.2mm. The large beaked surivors went on to reproduce when the conditions were
again favourable for breeding, and bc break size is heritable their offspring inherited
large beaks as well. The mean beak size inc bc only individuals w/ larger beaks were able to eat the hard
seeds. These large-beaked individuals survived and had offspring that inherited large
beaks from their parents.
Most examples of natural selection that can be observed within the lifetime of a scientist
tend to involve fairly small, subtle changes like this, which can be reversed over time (ex.
when the drought ended and plants again produced smaller seends, the average beek
depth of the finches returned to pre-drought sizes). But other changes that arise through
natural selection are more permanent and form a potential foundation for diversification