Evolution I & II- Key Terms
Adaption: Biological traits or characteristics that help an individual survive
And reproduce in its habitat.Adaptations are always “for” something, they perform
Specific functions that make an organism better suited to its environment.
• Human Eyes- enable us to recognize and respond effectively to things,
• Raccoons – primarily nocturnal animals, therefore they have good night vision, their
front paws are so sensitive they can virtually see with them to scavenge for food.
• Bats – bats can navigate the night skies and look for food with their echo-location system
Adaptions perspective: To understand how we manage to see, hear, respond to stimuli
scientists break these problems down into sub-tasks: how do you detect edges? How do you
assess the speed of an object or perceive a threat? Then… you can look for processes that are
capable of those tasks (relevant adaptations). Scientists categorized as “adaptationists” use this
label to describe how hypotheses about adaptive function guide their investigations. What about
“higher” mental processes… selective attention, memory encoding, memory retrieval, etc.? They
refer to the adaptive functions of mental activity. The adaptive functions evolved like all other
adaptations – through natural selection.Adaptations emerge in development as a result of
activation of relevant genes in interaction with relevant aspects of the environment.
Altruism: Behaviour in which the actor incurs a cost to provide a benefit to a
Not Altruism: Foraging/vigilance in groups because actor gains directly from behaviour. (The
Goose, and bird example are not examples of altruism.)
Behavioural genetics: The study of the genetic underpinnings of behavioral phenotypes such as
eating or mating activity, substance abuse, social attitudes, violence, and mental abilities.
Coefficient of relatedness (r): Probability that actor and recipient share gene in question.
Depends on how genes were inherited
Example: In humans we inherit two copies of every gene one from mom and
One from dad, however these copies are not always identical. Moreover, the one
You pass to your offspring and the ones mom and dad
Full Sibling (same mother & father): 0.5
Half Sibling (same mother or same father): 0.25
Aunts & Uncles: 0.25
First Cousins: 0.125
Monozygotic Twin : 1.00
Dizygotic Twin: 0.5
Cooperation : personal gain and gain for someone else. Hockey example ;
On a hockey team there is 6 players, one of the players Billy isn’t the best player but without him
you couldn’t play because you would be short players. So you decide that you might be able to
teach him how to play better.
Cost of teaching < Benefit of being on a winning team
What looks like a cost in the short term may pay off in the long term (Cooperation)
Cues of Kinship: Cues of Kinship (How do children know their mother/siblings)
• Mother’s association (rearing, breastfeeding, etc.)
• Co-residence with other children
Darwinian Fitness: Average reproductive success of a genotype relative to alternative
genotypes. (Note that fitness has nothing to do w/ biggest, strongest, and fastest
I.E. physical fitness)
Direct Fitness: Fitness from personal reproduction.
Hamilton’s rule: The reproductive benefit to the recipients (B) multiplied by the
Probability that the recipients actually have identical copies of the same gene, or
Coefficient of relatedness (r), must be greater than the productive cost to the actor (C).
Ex.: J. Haladane sacrificing 3 brothers
C=1 B=3 r= 0.5
C=1 B=1 r=0.5
(.5)(1) < 1= doesn’t fit the statement; Not altruism
C=1 B=2 R=0.5
• This means that you can increase your fitness by helping kin to successfully raise
Their offspring, sometimes even when doing so has negative effects on your own
• Because of inclusive fitness, natural selection can not only favour bavahiours that Increase an individual’s own reproductive success but also behaviours that