1.       Appetitive behaviours

2.       Defensive behaviours

3.       Reproductive behaviours

As the neuron has not changed over evolutionary time, which part of the nervous system has?

 The complexity of nervous system organizations

Brains appear to change in non-random ways as they increase in size. Provide an example of this.

In higher organisms over evolutionary time, the neocortex has shown greater increases in size in comparison to the brain stem. As well, early primates have more neocortex in comparison to other early mammals. They also have more of the brain devoted to visual processing.

                -Higher level processes require complex networks that are capable of being modified as conditions change.

The interesting hypothesis raised by this work is that the presence of smaller jaw muscles allowed for more of the area of the skull to be devoted to the brain. That is, smaller muscles could, in turn, require less bone to support them, and this could allow for more area for the brain. For the MYH16 mutation to be adaptive, this would also require other changes to be taking teeth in food preparation and/or a change in diet, such as eating more meat.

What do fossil records mainly tell us?

·         Evidence that comes from comparing a variety of living organisms with one another

·         Evidence that comes from comparing one type of organism, such as humans, with another that is believed to be older and thus more primitive, such as sea coral. Sometimes this results in surprising findings as when we discover that sea coral shares a number of gene sequences with humans.

Between 15 and 20 million years ago

Humans today share a number of characteristic with sea mammals such as:

·         Having little body hair

·         Chubby babies

·         Voluntary control over breathing

·         Subcutaneous body fat

·         The human brain contains proteins that are more similar to those found in shellfish than to any other known food source

Do infants have fewer neurons than adults?

No. As an adult you actually have fewer neurons than you did as an infant

What is the allocortex?

·         Archicortex

·         Paleocortex

The fact that the allocortex does not have the six-layered structure of the neocortex

·         The bottom layers (5 and 6): contains neurons that project to subcortical structures

·         Layer 4: contains local circuit neurons

·         Layers 3, 2, and 1: contain neurons that project to other cortical structures and receive information from layer 4

·         Cortical size

·         Organization

·         Area devoted to different types of cortical processing

·         Connectivity in network connections

Color and motion

What does the traditional view of brain structure and evolution emphasize?

The basic uniformity of structure of the neocortex across species

                EX: Cell columns in the neocortex are one classic example of this uniformity. The number of cells found in any given column in the neocortex has been shown to be approximately 110, regardless of where in the cortex it is located. This same number of cells has also been found to be constant across different species of mammals.

The number of cells found in any given column in the neocortex has been shown to be approximately 110, regardless of where in the cortex it is located. This same number of cells has also been found to be constant across different species of mammals. What is the one exception to this?

It is assumed that the human brain grew by increasing neuron number rather than increasing neuron size

Whales, dolphins, porpoises, and elephants

How much energy does the brain of a newborn take up?

About 80% (this reduces to about 45% by the age of 5)

The species that first used bones as hammers and anvils is referred to as what?

It refers to being wise or knowing (as the name implies, it is our cognitive flexibility that characterizes human behaviour and experience.

From a developmental and evolutionary perspective

Three levels

1.       Most basic level – vegetative functions: reflexes, sleep, and temperature regulation that would involve the spinal cord and brain stem

2.       Basal ganglia and its involvement in a number of movement-related processes

3.       Higher cortical processes

1.       Hierarchical integration through inhibitory control

2.       Encephalization

What is the type of control for the higher levels in the principle of hierarchical integration?

That the higher level structure, which evolved later than the reflexive ones, served the purpose of inhibiting and modulating these basic reflexes.

The midlevel processes continue to function normally and produce phenomena such as hallucinations and delusions. Thus, the symptoms of mental illness can be seen as particular brain areas functioning without higher level control. **Support for Jackson’s perspective has been supported by the type of thinking seen in the normal process of sleep and dreaming.

A reduction of inhibition of higher level cortical areas on emotional limbic processes.

1.       Reptiles

2.       Early mammals

3.       Recent mammals

**MacLean notes that these structures vary greatly in terms of chemistry and structure. This results in the three having different forms of memory, motor functions, and understanding of time and space.

That through rich interconnections, our brains can process a variety of information in the three somewhat independent, although not autonomous, ways.

The first level – the reptilian brain or R-complex - involves the brain stem and cerebellum. This level processes major life requirements such as breathing, temperature regulation, and sleep-wake cycles. Also involved in this level is olfaction (olfactory bulbs) and instinctive motor processes (basal ganglia). This level of processing represent fairly structured behavioural patterns involving basic activities such as territoriality, courtship, and hunting and also includes patterned displays related to these behaviours.

The second level of the triune brain is the paleomammalian brain – what does it involve?

What is Paul Broca quoted as having said with respect to the limbic system?

The limbic system was initially described by Paul Broca in the 1870s. Broca (1878) noted that the “great limbic lobe” exists as a common denominator in the brains of all mammals, and he described its location and structure in a variety of mammals.

Although mammals have been seen as evolving from reptiles, there are stark contrasts in three types of behaviours. What are they?

1.       Whereas reptiles such as lizards lay their eggs and the offspring must fend for themselves, mammalian offspring have a close connection with their mothers.

2.       Mammals use audio-vocal communication, which maintains maternal-offspring contact

3.       Play behaviour

Nursing in conjunction with maternal care is the source of the term “mammal”

Over the past 50 years, it has been shown that damage to one area in the limbic structure results in disrupted maternal behaviours. What is area?

·         It may have been related to the early mammal being nocturnal, which would emphasize vocalizations over vision

·         These cries may also represent the earliest and the most basic mammalian vocalizations from which language could develop

·         Summarizing the function of the limbic area, MacLean suggests that the structures in feelings in relation to self-preservation and the preservation of the species.

A process in which individuals report an inability to see objects but can accurately “guess” the location and motion of the object (generally found in people who have had brain damage)

Larry Weiskrantz in the 1970s

What does hemispheric lateralization mean?

Which tasks are specific to the left hemisphere?

Which tasks are specific to the right hemisphere?

Who initially studied hemisphere lateralization?

It is assumed that filling in the gaps is the result of neural network integration, which integrates information from a variety of cortical areas. In terms of evolutionary time, as the brain areas of the two hemispheres increased, the density of interconnections between the two was actually reduced. That is to say, as brain size in primates increases over time, the corpus callosum, and thus the relative number of interconnections, does not increase proportionally. Thus, each hemisphere is able to function more independently and also able to become more specialized for different tasks.

When the individual is engaged in private thought or left to think alone about both real and hypothetical events, such as what one would do in the future or what another person is thinking.

It appears as if there is a negative correlation between activities in the default network and networks associated with processing information from the environment. Overall, what does this suggest?

They lay out the basic body plan during development for all species. In an amazing manner, these genes are expressed in the embryos across species in the same nose-to-tail arrangement as their order in the chromosomes. That is, the first Hox gene develops the front aspects of the body, continuing in order until the final Hox gene develops the posterior aspects of the body.

·         It will produce normal eyes in fruit flies

·         This is possible because it appears that these genes turn on other genes, which in turn produce body parts related to a given species. Thus, they give the basic instruction, such as “build an eye”, and turn on specific genes that create the structure of the body part for that particular organism.

·         **Given this manner of functioning, it is assumed that Hox genes existed in a common ancestor prior to both flies and mice.

·         In mice, genes from the father contribute to the development of such basis forebrain structures as the hypothalamus and septum, but not the cortex.

·         Genes from the mother contribute to the development of the cortex, the striatum, and the hippocampus – but not the basic forebrain.

**Basically, maternal genes influence the more executive aspects of the brain, whereas paternal genes influence the more emotional aspects of the brain

In primates, which aspects of the brain have shown the greatest changes across species?

This is not to say that the motivational aspects of the emotional brain has decreased, but that more control of an intellectual or strategic nature has evolved in larger-brained primates.

Which parts of the body develops during the first month of pregnancy?

At about 18 days post conception, a process begins that results in the creation of what?

The creation of the neural tube from which the brain and spinal cord develop. Literally, a structure of cells begins to develop a groove, which closes over itself to form the neural tube. This tube then sinks inside the embryo. The anterior part of the neural tube increases in size as new cells develop. It is from these structures that the neocortex and its cerebral hemispheres eventually develop.

Unlike some other organisms, humans appear to develop all of the cortical neurons by which month of pregnancy?

By the sixth month of pregnancy

Structurally, what does the most anterior end of the neural tube during pregnancy become?

It becomes the forebrain, the midbrain, the cerebellum, and the hindbrain. The remaining part of the neural tube becomes the spinal cord.

Different parts of the neural tube expand differently in different animals under the control of specific genes. Provide an example that supports this claim.

As compared to other organisms, primates, including humans, have an extremely large neocortex, which develops from the most anterior part of the neural tube. In mammals, there are extreme differences in the number of neurons and in the surface area of the neocortex. For example, the surface area of a macaque monkey brain is some 100 times that of the mouse. The human brain has about 1,000 times more surface area than the mouse brain and about 10 times more than the monkey brain.

How many areas do humans have devoted to visual processing? How many areas do rodents have devoted to visual processing?

·         Humans have more than 30

·         Rodents have only 5

What is the basic unit of signal transmission?

The axon and the action potential that is generated within it

In the 1940s, the brain scientist Karl Lashley (1949) suggested that the only neurological characteristic for which there was a strong correlation with behavioural abilities was what?

Was the size of the brain in relation to the size of the body.

Who further extended the idea of Karl Lashley and in which book?

Jerison followed up on his idea in a now classic work, Evolution of the Brain and Intelligence (1973)

Jerison made a number of suggestions for using brain size to understand cognition. What were his suggestions?

1.       Brain size could be used to estimate other structural parameters, such as the density of neurons, the number of folds in the cortex, and the size of other neural structures. (**One exception to this involves the sense of smell – the olfactory bulbs appear to have little relationship to the size of other brain structures).

2.       The amount of information processed by a particular brain area is reflected in the size of that area.

3.       He was able to show that, in vertebrates, as body size increases across species, brain size expands in a mathematically predictable manner. Specifically, Jerison reported that each unit increase in the average body size for a species results in a 0.67 increment in the size of the brain. (*Recent work has shown the number to be slightly larger: 0.75)

How did Jerison consider the evolution of cognitive processes in terms of nocturnal vs. diurnal animals?

He speculated that early mammals that were known to be nocturnal could not rely on visual stimuli. Instead, they needed to integrate information from their auditory system with that of olfaction. Hearing told them that something was present and where it might be, and smell told them what it was. According to Jerison, this was the beginning of a nervous system that moved beyond simple stereotyped responses of reptiles to various types of visual stimuli. The nervous system of nocturnal mammals encouraged the evolution of spatial maps, which he speculated would late evolve into humans’ ability to create internal representations of external events. Over time, as mammals moved from being active at night to being active during the day, a more complex visual system also developed, which carried with it these previous capacities for spatial representations as well as the need for integration of information from a variety of sensory modalities.

One important development, according to Jerison, came with the larger brain in primates, including humans. This was the ability to connect information processing with time. Thus, such an organism could not only integrate information from a variety of sources, it could be aware of temporal contingencies. This eventually led to what?

A sense of self in humans – a self that integrates information and has a history that it remembers.

Nicholas Humphrey asked an interesting question. He wanted to know why great apes performed laboratory tests in a way that suggested they possess more intelligence than would be required for obtaining food in the wild. What was his answer?

His answer was that the intelligence was needed for social processes. According to Humphrey, there is a dynamic tension in social groups in that individuals seek both to preserve the overall structure of the group and outmaneuver others in it. This is, social groups lead to both cooperation and competition. In the sense that social intelligence also contributes to survival and reproduction, it becomes a force in the evolution of cognitive processes. Through this mechanism, the intelligence of a species can be increased. This is called either the “social intelligence hypothesis” of the “Machiavellian intelligence hypothesis”.

Researchers have used social intelligence as a way to study which other topics?

Deception, social learning, and the ability of one organism to understand the motivation and thinking of another.

How might you study social intelligence and brain size?

One approach has been to simply look at group size. However, group size alone has not been shown to simply look at group size. However, group size has not been shown to be strongly related to brain size across a variety of primate species.

If one considers group size, they may come to realize what?

They may come to realize that this is more a measure of potential interactions than actual interactions. For example, because primates groom one another, a measure of actual social interactions would be the size of the grooming group or clique. Indeed, this measure does correlate positively with relative brain size.

Scientists have taken two complementary approaches to the study of brain evolution and size. What are these two approaches?

1.       Allometric approach: focuses on the entire brain or large subdivisions

2.       Neuroethological approach: Examines the relationship between specific behaviors and underlying cortical structures. (Ex: you could ask whether one of the brain structures involved in spatial maps, the hippocampus, is larger in organisms that have a large territory that they explore than in those who do not. Ex2: ask whether the number of songs that an organism can produce is related to the number of neurons in the areas of the brain that control singing.)

Research show that primates who are primarily nocturnal have larger _____________ structures, whereas those who are awake in the day have larger ____________  ____________ areas in the brain.

Olfactory; Primary visual

(Looking at a longer evolutionary perspective, it appears that in primates, there has been a persistent tradeoff between olfaction and vision. Newer research has also shown this to be true on the genetic level. From examining genetic structure across a wide variety of species, these authors concluded that the evolution of color vision occurred in humans and other primates genetically similar to us as olfactory abilities were declining. This, of course, was not true in primates such as new world monkeys, which have not developed color vision)

As we look at the size of brains across species, we notice that organisms with bid brains are rare. Why would this be?

The common answer is that big brains require more energy than small brains. It is estimated that compared to the same amount of muscle tissue, brain tissue requires a metabolism that is more than 22 times faster.

It is estimated that compared to the same amount of muscle tissue, brain tissue requires a metabolism that is how many more times faster?

A metabolism that is more than 22 times faster

When we look at mammals, we observe that primate brains tend to be __________ times larger than brains of nonprimates with the same body weight.

2.3 times larger

When we observe humans, we discorver that, given our body mass, our brains are some __________ to ____________ times the size that would be expected in comparison to other mammals.

Three to five times

Humans support their brains without a large increase in the rate of basal metabolism. That is, metabolism in mammals appears to vary with ____________   ____________, not __________  __________.

Metabolism in mammals appears to vary with body size, not brain size

Metabolism or rate of energy use scales at about ________ of body weight.

it scales at about ¾ of body weight

What does the inconsistent relationship between brain size and metabolism suggest?

It suggests that, throughout evolution, human metabolic requirements may have been constrained. This may also have implications for adaptation and behaviour.

Increases in brain size must have been related to other factors, such as?

The types of foods early humans ate, the types of activities we engaged in, as well as the competition for food sources between infants and others around them. This competition between infants and others in turn may have limited the number of offspring humans produced as well as shaped the role of caregivers and extended families in providing food.

The development of human brains and their complex wiring both take more resources and a longer period of dependency than is seen in other species, which has significant implications for parent-child dependency and interactions. Elaborate on this further.

In terms of resources, newborns use 87% of their resting metabolism for brain growth and functioning, compared to 44% at age five and 25% in adulthood. These percentages are more than twice those found in chimpanzees.

Some researchers have suggested that the way humans have adapted to a larger brain it to do what earlier?

They give birth earlier. That is, compared to other mammals, humans are not fully developed when we humans are formed after birth. It has been estimated that about half of all synapses in humans are formed after birth.

It has been estimated that about half of all synapses in humans are formed when?

Are formed after birth

Human birth occurs during a phase in which it has been estimated that synapses are formed at the rate of _______________ per second, which would be ___________________ each minute.

40, 000 per second; 2,000,000 each minute

Compared to chimpanzees, whose cranial capacity increases 1.6 times after birth, the cranial capacity of humans increases how many times after birth?

It increases 4.3 times

Unlike nonhuman primate brains, the brains of human infants continue to grow at pre-birth rates for about how many months after birth?

For about 13 months after birth

If the growth rate of humans actually matched other primates, than the human infant would remain in the womb for how many months?

For 21 months

The female human pelvis is constrained by which requirements?

By requirements associated with walking upright on two feet. Thus, evolution appears to have made a tradeoff between the requirements of walking upright and the development of a large brain.

What are some tradeoffs that results from human females walking upright on two feet?

1.       An infant who is born less well-developed and in need of more support, compared to other primates

2.       Human births taking longer and placing the mother in more risk than is seen in other primates

As brain weight increases, what also increases?

Body weight

Humans and which other mammal have a brain weight that is larger than that predicted from the regression line based on body weight?

Dolphins

Primate species that eat mainly leaves have smaller brains than those that eat fruit. How can this be explained?

This is related to a variety of factors:

1.       Leaves require more energy to digest than fruit. Thus, energy that is used for digestion cannot be used by the brain.

2.       Also, there appears to be an inverse relationship between the size of the brain and the digestive organs of gut. In humans, there appears to be a gram-for-gram tradeoff over evolutionary time between the increase in brain size and the reduction of human digestive organs as compared to apes.

3.       As Allman suggests, fruit eating requires larger and more complex brains because an organism must know where the fruit trees are and also anticipate when they will be producing ripe fruit. A brain capable of noting color would also be beneficial for assessing the ripeness of the fruit.

4.       (Also Allman) The limited amount of ripe fruit must have resulted in greater competition that would be the case for leaves, which are more readily available.

(**This same type of thinking would also apply to meat eating in humans because meats are easier to digest than leaves, and hunting for meat sources requires a variety of complex cognitive processes and may be best accomplished in groups)

In humans, there appears to be a gram-for-gram tradeoff over evolutionary time between the increase in brain size and the reduction of what?

The reduction of human digestive organs as compared to apes

What are the reasons for which Allman suggests that fruit eating requires a larger brain?

Fruit eating requires larger and more complex brains because an organism must know where the fruit trees are and also anticipate when they will be producing ripe fruit. A brain capable of noting color would also be beneficial for assessing the ripeness of the fruit.

There is a strong relationship between brain size and longevity, which in turn is related to food source. Provide an example to support this claim

The gorilla, which eats leaves and plants, has a relatively smaller brain and shorter life span compared to other primates

Among primates, humans have the longest life span and the largest brains. Unfortunately, these data were not extended to other mammals known for life spans similar to humans – such as?

Horses, whales, and elephants

What is the Encephalization Quotient (EQ)?

Brain weight in relation to an organism’s body weight

Which is the better predictor of mental abilities: EQ or absolute brain size?

Absolute brain size

                (*This is consistent with brain imaging work from the neurosciences, which shows that the actual size of a body part does not map directly to the size of its representation in the brain. Rather, it is the sensitivity or acuity of the sensory and motor processes that reflect the amount of cortical tissue devoted to those processes. Thus, our hands and tongue have more cortical areas devoted to them then do our feet, even though our feet are larger than our hands)

Across species there is differential representation of body parts in the brain depending on their utilization. Provide an example to support this claim.

The hands of raccoons, the tails of spider monkeys, the snouts of coatimundis, and the lips of llamas all have increased cortical areas devoted to their control. Thus, greater sensitivity in the sensory and motor system results in larger cortical areas devoted to those tasks.

There are two ways of conceptualizing the relationship between cognitive abilities and brain areas. What are they?

1.       “Mental module model” or “Swiss army knife model”: This model suggests that the brain, like a Swiss army knife, contains a number of modules devoted to specific tasks. Underlying this model is the suggestion that evolution of cognitive abilities carried with it the requirement for a new neural module in the brain.

2.       “Alternative to the mental module model”: This model suggests that increased abilities come with a global increase in neurons and their interconnectedness within the brain that allows for greater information processing.

Which model do modern neuroscientists favor more: “Mental module model”/“Swiss army knife model” or the “Alternative to the mental module model”?

They tend to favor the “Alternative to the mental module model”

As the primate brain becomes enlarged, what happens to the proportional number of connections through the corpus callosum between the left and right hemispheres?

The proportional number of connections has been reduced.

What do both models (“Mental module model”/“Swiss army knife model” and “Alternative to the mental module model”) suggest?

They both suggest that, over evolutionary time, the development of higher cognitive processes required an increase in cortical tissue. Of course, an increase in cortical tissue would require a larger skull area to house the brain. This gives us an opportunity to create a gross estimate of cognitive abilities from the fossil record by examining the cranial capacity of a species.

Across primates, does the percent of gray matter stay constant or does it fluctuate?

The percent of gray matter remains basically constant.

Gray matter is involved in which processes, while white matter is involved in which other processes?

Gray matter is involved in the processing of information, whereas white matter is involved in moving information from one area of the brain to another.

Is it gray matter or white matter that increases as brain size increases?

White matter

Whereas about 9% of the brains of lower primates are composed of white matter, _______% of the human brain is white matter, while gray matter remains a constant percentage.

34%

Are human male brains larger than those of human females?

Yes. In fact, the brain size of males is approximately 100g larger than that of females, when adjusted for body weight or for height. These same gender differences in brain size have also been reported in children.

What is one possible way in which we may come to understand why human male brains tend to be larger than those of females?

Recent research suggests one way to understand these differences may lie in the manner in which male and female brain are “wired”.

·         Examining the white matter of the brain, gray matter of the brain, and cerebrospinal fluid, Gur and his colleagues found differences in their distribution in the brains of males and females.  Females had a higher percentage of gray matter (55% vs. 51%) whereas males had a higher percentage of white matter (40% vs. 38%). Males also had more cerebrospinal fluid (CSF) in their sulci (8% vs. 6%).

Who has more gray matter: women or men?

Women

Who has more white matter: women or men?

Men

Who has more cerebrospinal fluid: women or men?

Men

What are the “sulci” of the brain?

The depressions of fissures in the surface of the brain

How do males and females show different patterns in relation to the two hemispheres of the brain? What do these finding imply?

·         Males had more gray matter in the left as compared to the right hemispheres and more CSF in the right hemisphere as compared to the left hemisphere.

·         Females showed no differences in gray matter, white matter, or CSF between the two hemispheres of the brain.

Ø  One implication of these findings for cognitive processing is that females have more tissue available for computational processes, whereas males have more for the transfer of information across different regions of the brain.

The greater lateralization in males as compared to females is also consistent with the lateralization of what?

Function literature. In terms of function, it has been shown that language is more lateralized to the left hemisphere and spatial processing is more lateralized to the right hemisphere in males as compared to females, who show less lateralization of function.

What is the task of sensory systems?

To derive meaning from energy that exists in the external world

A little more than 500 million years ago, there was an increase in the diversity of life forms of earth. Organisms existing at that time lived where?

In water

Frequencies that are least affected when passed through water correspond to those that our ___________ system is most sensitive to.

Our visual system – thus, although the visual system continued to evolve as organisms lived outside of water, the physical frequencies processed by our visual system harken back to adaptations manifested more than 500 million years ago.

Which types of frequencies are used by electric fish to probe and sense their environment?

Low frequencies (approximately 100Hz)

During the period of increasing diversity more than 500 million years ago, new genetic variations developed that produced different types of photoreceptors. What were they and how did they come to be?

·         One type of photoreceptor was sensitive to low light and evolved in the rods in our eyes – which allows us to see dim light

·         Another type of photoreceptor was produced that required greater illumination. Over time, the receptors of this system became sensitive to different frequencies in the visual spectrum. These were the forerunners of the cones in our visual system, which allow us to experience colors. These genes for cones differ in different species, resulting in different sensitivity to different parts of the visual spectrum.

Which of our systems senses movement and sends this information to the hindbrain, which in turn sends signals to the eye muscles? What does this allow us to do?

·         The vestibular system

·         This enables our eyes to move in the opposite direction from our movement, in order to compensate for that movement and leave the image on our retina stable.

Further corrections of our interpretation of visual information take place in the cerebellum. What does the cerebellum do in the case?

The cerebellum compares changes in eye velocity and head velocity. The front-facing location of our eyes enables us to determine depth, which would have been helpful for both eye0hand coordination as well as catching prey.

True or false: The olfactory bulb is smaller and simpler in humans than in other primates?

True

How do we determine what external information we should be paying attention to?

·         The most basic answer is that we pay attention to those aspects of the environment that have signals of value to us (EX: Loud noises)

·         A further answer is that we pay particular attention to those aspects of the environment that have signals of value to us (because humans have never been a solitary species and have always lived in social groups, a further answer is that we pay particular attention to the cues of others, as especially facial expressions. Humans not only have carefully tuned visual systems for noting changes in facial expressions, we also have large cortical areas that produce facial expressions (e.g., directing muscles that retract the corners of the mouth and smooth or wrinkle skin around the eyes).

Part of the limbic system, the ______________, receives input from areas of the cortex involved in facial expression.

Amygdala

What does damage to the amygdala do?

Damage to this area results in the lack of ability to detect emotional expression, even though the person can identify the face.

When we are watching someone perform a task, there are neurons in specific areas of our brain that fire as if we were performing the task ourselves. Which types of cells are involved in this process?

Mirror cells (also referred to as mirror neurons)

Mirror cells may be involved in observational learning as well as what?

Development of an understanding of others

Although humans do not have the largest brain either in absolute or relative terms, humans do have the largest what?

Humans do have the largest number of cortical neurons. This results from the high density of neurons in the human brain.

The neocortex evolved an amazing level of direct access to the motor neurons of the medulla and spinal cord. What does this enable?

This enables humans to have a high degree of dexterity in our hands as well as to control the muscles of our eyes, jaws, face, tongue, and vocal cords.

Humans have better control over their breathing than do most other species. What are the obvious advantages to this?

The obvious advantage of this arrangement is the ability it gives humans to produce vocal sounds as well as facial expressions

True or false: The modern human brain appears to contain areas that are not found in other primate species?

False. The modern human brain does not appear to contain any areas not found in other primate species.

·         *However, humans use these areas for different purposes. For example, similar areas to those humans use for language, such as Broca’s and Wernicke’s areas, are also found in other primates.

What does “hominin” mean?

Any of the modern or extinct bipedal primates, including humans

Why was hominid replaced by hominin?

It was replaced in order to be more precise in naming species

the remote desert region In 1974, a discovery was made in of Ethiopia. Explain this discovery.

A skeleton of a human ancestor that lived some 3.2 million years ago. She was the first autralopithecus afarensis discovered and was called “Lucy” after the Beatle’s song – Lucy in the sky with diamonds. Lucy walked on two legs although she had a more ape like head, long arms, and a brain about ¼ the size of current day human brains. Findings have suggested that Lucy’s species had a fourth metatarsal and arches in their feet similar to modern day humans – thus, they were able to walk upright.

In which year was the hominin “ardipithecus” discovered?

2009

It has been estimated that “ardipithecus” around how many years ago?

They lived before the time of Lucy, 4.4 million years ago in an area of Africa that is now Ethiopia.

Describe what was concluded on the study of “ardipithecus”.

·         Included most of the skull, teeth, pelvis, hands, and feet

·         Ardipithecus does not resemble a chimpanzee, gorilla, or other nonhuman primate – this was a species that was neither primate nor human

·         Skeleton was that of a females

·         She was about four feet tall

·         She weighed about 110 pounds

·         Based on her skeleton, she is assumed to have walked upright and planted her feet flat on the ground

·         It is also assumed that she could move through the tops of trees because she had an opposable big toe, which could grasp limbs

·         Other evidence suggests that she lived in woodlands rather than grasslands

What is the second oldest hominin species that has been discovered?

Australopithecine – who appears to have walked upright between three and four million years ago

How do we know that Australopithecine walked upright?

·         Fossil records of footprints found in Tanzania

·         The structure of the skeleton – pelvis, spine, and feet

·         The hips and legs appear better suited for walking on the ground than on tree limbs

·         The opposing big toe had been lost

Australopithecine overlapped with another species of the genus Home – what was this species called?

Homo habilis

When did Homo habilis live?

From 2.4 million to 1.6 million years ago

What is Homo habilis’s nickname? Why?

“Handyman” because of the tools that were found with it

The first specimen of the species Homo habilis was discovered by whom?

By Leakeys in Africa in the 1960s

Describe the features of Homo habilis.

·         Its arms were somewhat long and its legs somewhat short

·         This species had hands like we do today, with opposing thumbs

·         This species had smaller teeth

·         The height is thought to be around five feet, with a weight of 100 pounds

·         The brain size of this species was around 650 cc

Describe the tools that were found at the site of the Homo habilis.

The tools found were basically stones with a sharp edge (could have been used for a variety of reasons including food preparation)

Around which time was the Homo Erectus discovered?

Around the time that the Homo habilis was discovered

Homo Erectus is estimated to have live around how many years ago?

Around 1.8 million years ago

In terms of Homo Erectus and their tools – what was found?

They used more sophisticated tools and probably fire. They were also though to make containers for food and water.

**Interestingly, once the tools appear in the fossil record, they remain largely unchanged, suggesting that the species lacked innovation.

What are the estimated physical features of Homo Erectus?

·         Tall (at least six feet) and slender

·         May have been more efficient at walking than current-day humans

·         Brain size around 1,000 cc (which is about less than current-day humans)

In which regions were the fossils of Homo Erectus found? What does this suggest?

·         Fossils of this species found in Africa, Asia, and Europe

·         This suggests that this was the first of the hominins to migrate out of Africa

What isolated Homo Erectus in the regions of Europe, Asia, and Africa?

The ice age – which happened less than a million years ago

What happened to the populations of Homo Erectus in the regions of Africa, Asia, and Europe?

·         Those in Asia become extinct

·         The European group led to Homo Neanderthalensis

·         The African group led to Homo Sapiens

In1856, near the time Darwin was preparing to publish his book On the Origin of Species, a German school teacher found some human-like bones in a cave in the _____________   ____________

Neander Valley

What was special about the bones that were found in Neander Valley?

 It was clear that these bones – and other found previously in Belgium as well as other parts of Europe and the Middle East – were different from modern humans. These individuals had a broad rib cage, wide pelvis, large protruding jaws, large nasal area, long thick skulls, and projecting brow ridges. The brain size of 1, 450 cc may have been slightly larger than modern humans but is also consistent with bulkier body size. The body type is associated with colder climates, as opposed to the slender humans of Africa.

Homo Neanderthalensis was considered to be what?

A distinct species of humans who lived between 230,000 and 30,000 years ago

Why to do see two ways of spelling “neanderthal” and “neandertal”?

Because the spelling of the German word for valley was changed from “thal” to “tal” in the early 1900s

What can be inferred about the Homo Neanderthalensis based on his tools?

·         Judging by the variety of tools and weapons found with them, it is likely the Neandertals were formidable hunters

·         Their tools appear to have been made for specific purposes

Which species was the first to have been found to bury their dead?

Homo Neanderthalensis (**One burial site dates from about 100,000 years ago)

Which species decorated their bodies with pigments?

Homo Neanderthalensis

Neandertals overlapped with Homo Sapiens in Europe and they probably came in contact with one another, there was little in the way of mating between the two groups. Is this belief still held today?

No. Since 2010, the popular belief has been that mating did take place

In 2010, a finger bone was discovered in the Denisova cave in southern Siberia that suggests what?

It suggests that another Homo group existed along with both the Neandertals and modern humans.

DNA analysis indicates that this group, called the Denisovans, diverged from Neandertals about how many years ago?

About 640,000 years ago

300,000 years ago, when the Neandertals went into iceage Europe, where did the Denisovans go?

They went east

There is evidence to suggest that Denisovans were present in Asia about how many years ago? What is the evidence?

·         45, 000 years ago

·         This is shown by the fact that Denisovans share DNA mutations with people from Papua, New Guienea, with 4% to 6% of their DNA in common

·         This suggests complex interactions between early humans, the Neandertals, and the Denisovans.

Homo Sapiens are also referred to how?

As modern humans

Modern humans are thought to have appeared in Africa how many years ago?

Somewhere between 195, 000 and 160, 000 years ago, although the exact date varies depending on the research method used

What is the brain size of modern humans?

Somewhere between 1, 350 cc

What are the characteristic physical features of Homo sapiens?

·         -Small pelvic area

·        - Prominent chin

·       -  Forehead that rises sharply

Around when did modern humans begin to migrate out of Africa?

Around 90, 000 years ago, although recent findings suggest it might have been earlier, initially through the Middle East

Homo sapiens are associated with sophisticated tool use. Elaborate.

·         Beginning about 80, 000 years ago,  bone harpoon points appeared

·         By 40, 000 years ago, a wide variety of materials such as flint and bone were used for tools such as needles and fishhooks

·         Clothing and art began to appear (this included objects worn as decorations on the body)

From a psychological standpoint, what does the creation of art by the Homo sapiens suggest?

It suggests the emergence of symbolic behaviour for the first time

A variety of art objects dating from around 30, 000 years ago have been discovered. What was found in Germany? What was found in France?

• ·         Germany: a series of animal figurines from about 34, 000 years ago were discovered. These included figures of a lion, panther, bison, horse, reindeer, and mammoth. Carved from ivory, they were discovered in the caves of Vogelherd.
• ·         France: a series of cave paintings depicting a variety of animals dating from 32, 000 years ago were discovered. The exact meaning of the cave paintings of this era is unknown, although some scholars have suggested a religious significance.
• *Based on these types of behavioural changes, it is argued that the archeological record has changed more in the last 40, 000 years than it had in the prior million years

Compared to other human species, Homo sapiens have modified their environments in ways not seen previously and in a relatively short time. Some researchers speculate that one aspect associated with these changes some 50, 000 to 40, 000 years ago was changes in what?

Neural capacity that allowed for language