Lecture 14 - Evolution (Cognitive Neuroscience, UU)

Development of traits:

• Variation
• Heritability
• Natural selection / adaptedness

Key factor is selection pressure

Are we dealing with common descent or with convergence?

• Common descent: we lijken meet op apen omdat deze dichterbij liggen in de evolutie
• Convergence: unrelated species have come up with similar solutions to similar problems

• Homology: a trait is of common descent
• Analogy: a trait is functionally similar but was not derived from the same ancestor

False dichotomies in evolution studies:

• Innate – acquired/learned
• Genes – environment
• Instinct – learning
• Nature – nurture

What is innate? Different opinions:

• Present at birth
• Behavioural difference caused by a genetic difference
• Adapted over the course of evolution
• Unchanging throughout development
• Shared by all members of a species
• Present before the behavior serves any function
• Not learned

Lorenz: behavior can be dissected in innate and acquired/learned components.

• Animals reared in complete isolation would show behavior that is completely innate, = Kaspar Hauser experiment

Lehrman: behavior is the result of a complex interaction between the individual and its internal and external environment.

No new neurons are generated after birth.

At birth there are (too) many synaptic connections, so pruning takes place.

Does absolute size matter? No, if the body is bigger, the brain is too. So look at relative size.

Cortex size does matter. Forebrain complexity is characterized by cell groups.

Brains tend to get bigger and bigger. Why? 3 hypotheses:

1. Foraging hypothesis: differences in brain size are due to differences in the way animals get their food.
2. Social intelligence hypothesis: the more social interactions are needed (larger social group), the larger the brain (relatively).
3. General intelligence hypothesis: species differences in social learning and innovation are linked to brain volume.

Group size does not covary with primate general intelligence score.

Summary:

• Cognitive traits covary together in primates, raising the possibility of a primate general intelligence, that includes elements of social intelligence
• The g measure covaries with brain volume measures but not group size
• High g species appear in several groups, suggesting independent evolutionary events
• Conserved general processes, as opposed to specialized modules, may be an important part of primate cognitive evolution and the evolution of social learning

Misinterpretations of the view of evolution:

1. Medieval view of evolution (scala naturae)
   1. Scant consolation
   2. There is no cognitive scaling in nature
2. Confounding evolution and mechanism
   
   1. Tinbergen’s 4 why’s regarding behavior: evolution, function, development, mechanism (causation).
   2. Adaptive specialisations: the whiskers of a bunny are well represented in the brain
   3. Based on food storing birds: it is hypothesized that they have adaptive specialisations for spatial memory. However, this is not the case.
   4. In neuroecology, we can only look at clues of nature. However, these clues can be misleading because they are not explanations.

Evolutionary considerations are explanations for human cognition. The mind/brain has evolved as a result of selection pressures in the Stone Age.

Why evolutionary psychology doesn’t work:

• No cognitive fossils: thoughts can not be fossilized
• Cultural evolution: there has been a change in the way we think
• Evolution is not about mechanism

So we are dealing with common descent AND convergence.

1. Common descent: homology; neural and genetic mechanisms that are present in all of us
2. Convergence: auditory-vocal learning, we made use of the shared mechanisms differently.

Also specialization: human language syntax

Conclusions:

• Development is a complex dynamic process, NOT simply nature vs nurture
• Evolution is about a reconstruction of the history of traits, NOT about their underlying mechanisms
• Brain and cognition have evolved
• Both common descent and convergence have played their roles
• Language likely evolved very recently, only in humans

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