Exam review, Evolution of Cognition Flashcards
what is Encephalization
is the increase in brain size, relative to body size
The trouble with a focus on brain size and cranial capacity is that what
it measures only the dimensions of the brain, not neural activity or structural complexity
where does the majority of brain activity takes place
The relatively thin cerebral cortex
Humans have highly textured brains, allowing for more overall what
cortical surface
how many neurons in the human brain
85 billion neurons in the human brain
what are the three major regions of the brain
the cerebrum
• the cerebellum
functions)
• the brain stem
what does the cerebrum
(“higher functions”)
what is the cerebellum
(motor & muscles
what is the brain stem
(“core functions” i.e. breathing, heartbeat, etc.)
what are Endocasts
are replicas of the insides of early and modern human braincases. They represent the size and shape of the brains that once occupied the braincases
what is Paleoneurology
The study of the evolution of the brain structure and function
what is EQ (Encephalization Quotient)
The ratio of actual brain size of a species to the expected brain size of an “average” mammal of that particular body size
what tends to have the largest EQ
n the animal kingdom, proportionally larger brains differentiate all mammals from reptiles, and among mammals primates tend to have the largest “encephalization quotient” (EQ)
Different sources cite different EQ values for humans; EQ is what kind of ratio
a sample-dependent ratio
why must we must be cautious about comparing specific species
The hominin fossil record is fragmentary and incomplete
how does EQ and Hominin Evolution relate to
Autralopithecines & Paranthropines
Early hominins are smaller in body size to great apes, but have equally sized brains.
• Therefore, gracile and robust early hominins were more encephalized than modern great apes
how does EQ and Hominin Evolution relate to
Early Genus Homo
H. habilis has a relatively small body, but a brain size that overlaps with the largest gorillas.
• H. erectus/ergaster’s leap in body size coincides with a proportionately faster leap in brain size
EQ and Hominin Evolution relate to
Archaic Hominins & AMH
The jump from H. erectus cc to Archaic hominin cc is the most accelerated in the fossil record!
• AMHs are more encephalized than Neanderthals because they are smaller, but have brains of nearly equal size
Over the last 6 million years: brain size has…
has increased absolutely and relatively (to body size)
In last 2 million years: increases to brain size….
have sped up, while increases to body size have slowed
is encephalization an important evolutionary adaptation for humans
yep
what are the Hominin Encephalization
Tool Use (“Man the Tool-Maker”)
Hunting (“Man the Hunter”)
Social Intelligence Hypothesis
what is the Tool Use (“Man the Tool-Maker”) theory
Stone tool making required complex conceptual abilities, forethought, planning, & better motor coordination
what are the problems with the Tool Use (“Man the Tool-Maker”) theory
Chimps make simple tools in the wild and can be taught to make stone tools, so a large brain is not necessary.
• Encephalization trend begins EARLIER than stone tools appear (~6 mya vs 3.3 mya).
• Major changes in brain size occur when there are only slight changes in stone tools
what is the Hunting (“Man the Hunter”) theory
Hunting selected for larger brains because it required:
• more sophisticated knowledge of the environment,
• the ability to plan complex strategies
• better cognitive skills to manipulate the complex social relationships inherent in a social life involving food-sharing
what is the problem with the Hunting (“Man the Hunter”) theory
Encephalization was occurring BEFORE there is any clear evidence for hunting or food-sharing.
• Some carnivores (lions) use complex ambush strategies without large brains or language
what is the Social Intelligence Hypothesis
The intellectual requirements of increasing social complexity was the main stimulus for encephalization. Required:
• Sharper social skills
• Better communication
• Technology and hunting also contributed, but these were not the prime movers
what is the problem with the Social Intelligence Hypothesis
Many primate societies have complex social behaviors, but no trend toward encephalization
what are the problems with the brain
An Expensive Organ
Childbirth and Growth
why is the brain as An Expensive Organ a probelm
In humans:
• 2% of human body weight
• 20% - 25% oxygen supply & blood flow
• Other great apes can’t afford the metabolic cost for both large body size and neurons, so there is a trade-off.
• Suzana Herculano-Houzel (neuroscientist) says cooking offset this trade-off in humans (TED TALK)
why is Childbirth and Growth a problem with the brain
Because brain tissue grows less than other tissues, large brains mean babies are born with larger heads, causing problems in delivery.
• This means that as hominin brains became bigger, babies had to be born EARLIER in their development (allowed for more brain growth after birth).
• This created a much longer period of infant dependency, requiring much more time and effort to care for and rear offspring.
what is Intelligence
The ability to engage in flexible, problem- solving behavior
Characteristics of the modern mind include
Self awareness
• Memory
• Awareness of the future
• Analogical reasoning (recognizing likeness)
• Symbolization - Making one thing stand for another. This is essential in language.
Animals possess SOME, but not all of these characteristics.
what is The Great Debate of Cognitive Evolution
Evolution of intelligence and the mind MAY OR MAY NOT be linked in a simple way to changes in brain size. The presence or absence of such a link is currently being debated
what are the 2 positions in the cognitive evolution debate
generalized and modular
what is the generalist view
Intelligence in hominins is a unitary phenomenon that is linked to gradual increases in brain size.
• In other words, the brain is a generalized computer in which “intelligence” is determined by its size and complexity
what is the modular view
Intelligence is “modular” (i.e. partitioned into different functions), with different modules controlled by different circuits in the brain.
• In this view, overall “intelligence” is much more complex, and is determined by a combination of overall computing capacity AND the degree to which the modules are connected with each other.
what is Evidence for General Intelligence
Studies of animals in general show a close correlation between “intelligence” and larger brains when you control for body size and eliminate the parts of the brain that only control physiological functions (dolphins and African Gray Parrots for example)
what is Evidence for Modular Intelligence
There is evidence for modularity in a few animal species.
• Example: Jays can remember where they hid thousands of individual acorns, but they perform poorly on some other types of intelligence tests that don’t involve memory
Gardiner and other psychologists and linguists proposed a model of the mind as a set of what
modules (multiple intelligences).
Archaeologist Steven Mithin has applied this modular theory to human evolution. His multiple intelligences are
Generalized Intelligence Social Intelligence Natural History Intelligence Technical Intelligence Linguistic Intelligence
what is Generalized Intelligence
A small core of basic memory and learning skills necessary for survival. (This is present to some degree in ALL mammals.)
what is Social Intelligence
Concerned with social interactions. This is more highly developed in primates than in most other mammals, so our early ancestors probably had a well developed social intelligence module
what is Natural History Intelligence:
Knowledge of the environment, including food sources, shelter, and predator-avoidance.
what is Technical Intelligence:
Use and manufacture of tools. The earliest evidence is stone tools, but before that our ancestors probably had chimp-like tool-using behaviors
what is Linguistic Intelligence:
TRUE LANGUAGE, with sounds standing for things and concepts and rules of grammar and syntax
what does Mithin argue about the cognitive leap
that the “cognitive leap” occurred when the linguistic module grew to overlap and link the other modules. • Supposed this occurred suddenly at c. 50- 45,000 BP, possibly facilitated by a neurological reorganization of the brain
what is Evidence for Modular Intelligence
Archaic Hominins (BEFORE AMH):
• Successful hunting strategies + great skill in stone tool manufacture.
• BUT, Archaics were rigid in other behaviours and lacked innovation in some.
• No evidence of decoration or obviously symbolic artifacts before Upper Paleolithic
However, our ideas of how early these innovations appear is updating with every passing year
what are alternate hypothesis’
the CAPACITY for complex cognition may have evolved long before complex thought patterns actually developed.
• By c. 50,000 BP: human population densities had increased to the point that groups were interacting with each other much more frequently, creating the conditions for the cumulative nature of culture to create and reinforce behavioral complexity
what is evidence for “earlier” innovation
2014 discovery
• Maros Caves, Sulawesi, Indonesia
• Cave paintings • ~ 40 kya
