3 lecture 9

Question 1

During what time period did humans begin to walk upright and make simple tools
as well as brain size increased slightly

Answer 1

6–2 million years ago

Question 2

what species was lucy

Answer 2

Australopithecus afarensis

Question 3

when did lucy exists

Answer 3

3.85-2.95 million years ago

Question 4

how long did Australopithecus afarensis last

Answer 4

Existed for around 900,000 years

Question 5

how was Australopithecus afarensis like apes

Answer 5

Grew rapidly after birth and reached adulthood earlier than modern humans
Long, strong arms, curved fingers adapted for tree-climbing Apelike face proportions
Small brain

Question 6

how was Australopithecus afarensis like humans

Answer 6

Small canine teeth Bipedal (walked upright)

Question 7

what is Bipedalism

Answer 7

walking on two limbs instead of four
apes can do so occasionally, but are they are posturally more suited for
using four limbs
–for humans to do this required changes in the hips, lower back and pelvis

Question 8

how did Proportions of arms/legs change

Answer 8

long arms are adaptive for climbing and swinging through trees

While A. afarensis was bipedal, changes in the proportion of arms/legs/torso wouldn’t occur until later

Question 9

when did Brain and body size increase

Answer 9

From 2 million–800,000 years ago

Question 10

what else happened From 2 million–800,000 years ago

Answer 10

During this time period early humans spread around the globe, encountering many new environments on different continents.
Greater use of tools and fire (though not yet controlled use)
These challenges, along with an increase in body size, led to an increase in brain size

Question 11

when did Homo erectus exist

Answer 11

1.89 million to 143,000 years ago

Question 12

what species was the first to live outside africa

Answer 12

Homo erectus

Question 13

what are the traits of homo erectus

Answer 13

Oldest known early humans with human-like body proportions –longer legs, shorter arms relative to the torso –indicates adaptations for ground dwelling and loss of adaptations for tree-climbing
Expanded brain case relative to the size of the face
May have been one of the earliest humans to show reduced hair or fur

Question 14

what species is our closest extinct human relative

Answer 14

Homo neanderthalensis

Question 15

when did Homo neanderthalensis exist

Answer 15

200,000-28,000 years ago

Question 16

what were the traits of homo neanderthalensis

Answer 16

Lived in the cold
–shorter and stockier than us, thought to be an adaptation to the cold
Made and used a diverse set of sophisticated tools
Skilled hunters, also ate plants Controlled fire
Lived in shelters
Wore clothing
Buried their dead
–marked graves with flowers or offerings

Question 17

is it possible to study neanderthal DNA

Answer 17

yes, neanderthal genome project

Question 18

when did homo sapiens happen

Answer 18

200,000 years ago to present

Question 19

what are the traits of homo sapiens

Answer 19

Lighter skeletal build compared to earlier humans
Less heavily developed jaws, with smaller teeth
Less (if any) heavy brow ridges and prognathism of other early humans.
Skull reorganization – a thin-walled, high vaulted skull with a flat and near vertical forehead.
Very large brains

Question 20

Based on current fossil data, how many “bursts” or big increases in brain size have occurred

Answer 20

2

Question 21

when did the first “burst” happen

Answer 21

The first occurred with the split between the australopithecines and the homonids –Around the emergence of Homo erectus

Question 22

when did the second “burst” happen

Answer 22

The second was around the time of the emergence of the first Homo sapiens

Question 23

what is brain size related to

Answer 23

Brain size is generally related to body size
–We see this relationship across species
Bigger animals have bigger brains

Question 24

So what could lead to those big shifts or bursts in brain size that we see

Answer 24

In general, H. erectus was significantly larger and had a larger brain than ancestral hominids
These things appear to go together
Large size makes them better equipped to get food
–chase carnivores off of carcasses
–hunt animals by running them to heat exhaustion
–dig deeply for tubers which are more energy rich than grasses
A better diet was critical to produce a large, metabolically expensive brain

Question 25

are brains energy-consuming

Answer 25

Brains are energetically expensive, you need a way to give them energy

Question 26

what did humans do to provide the right amount of energy

Answer 26

Early humans, like apes, ate mostly fruit, plants, insects
Transition to eating meat was important for growing and maintaining a larger brain
This meant there needed to be a way to hunt that food
–we see the appearance and development of stone tools

Question 27

what is cooking important for

Answer 27

getting more calories out of the food

Question 28

who pushes the idea that the expansion in the size of homo erectus’ skull was due to the additional energy released from cooking meat

Answer 28

Harvard primatologist Richard Wrangham

Question 29

what is The strongest evidence of habitual cooking including

Answer 29

stone hearths
–clay cooking vessels –bones encircling patches of dark ground or ash
Evidence of “controlled” fire and cooking here
Appear around 1.4 million to 790,000 years ago

Question 30

did cooking lead to the split between Homo and australopithecines

Answer 30

probably not
(though the hunt is still on for finding earlier evidence of controlled fire use)
However, cooking could have contributed to the increase in brain size after the split from australopithecines

Question 31

what does all this mean?

Answer 31

Homo erectus was a little larger and had a larger brain
Large size makes them better equipped to –chase carnivores off of carcasses
–hunt animals by running them to heat exhaustion –dig deeply for tubers which are more energy rich than grasses
A better diet probably allowed them to evolve smaller teeth and smaller intestines (because they no longer have to get calories from nutrient poor grasses)
Could devote that energy to producing a large, metabolically expensive brain
Having a bigger brain helped them to invent new tricks for improving the diet (e.g. cooking, new tools for hunting, getting more nutritious food like eggs or shellfish)

Question 32

So what do you need to have a big brain

Answer 32

1) Brains are energetically expensive, you need a way to give them energy
2) Need to actually grow that big brain

Question 33

why is Need to actually grow that big brain important

Answer 33

This is important because when do you grow a brain? Can do so in utero, BUT this can complicate childbirth

Question 34

what happened in order to make the shift from quadrupedal to bipedal walking

Answer 34

To move from quadrapedal to bipedal walking, the orientation of the pelvis, lower back and hips changed
Instead of holding the body at an angle from the hips to the head, the reorientation resulted in the torso and all of the organs resting vertically on top of the hips and pelvis

Question 35

This reorganization was significant not just for walking but also for what

Answer 35

child birth

Question 36

what does upright walking result in

Answer 36

Results in a vertical shortening of the pelvis Limits how wide the pelvis can be

Question 37

At the same time, brain size and therefore skull size is increasing
–how can both of these things happen?

Answer 37

This is known as the “obstetric dilemma”

Question 38

what is “obstetric dilemma”

Answer 38

how do you fit a large head through a small, short pelvis and birth canal?

Question 39

what is the solution to Obstetric Dilemma

Answer 39

Sutures and Fontanelles

Question 40

explain the solution to Obstetric Dilemma

Answer 40

The ancestor to humans, chimps, and bonobos already had the start of a solution to this
There skull of great apes is not one solid piece of bone, but a number of large pieces of bone connected by more flexible tissue
These connections between the large bones are called SUTURES
The soft spots are called FONTANELLES
Before birth, the sutures and fontanelles are soft, which allows the skull and brain to be molded and squeezed a little as the head passes through the birth canal
Then, after birth, these sutures solidify or fuse, resulting in a continuous, solid skull –But WHEN after birth this happens is important

Question 41

what is hypothesized between larger brains and diets

Answer 41

We hypothesize that there would have been strong, coordinated natural selection for larger brains and adaptations that lead to better dietary quality

Predict there would be selection for any mutation that took advantage of the flexibility of the skull and extended the time for brain growth after birth
–Better diet and cooking likely also influenced increase in brain size (and brain size influenced diet and cooking)

Question 42

We then see a plateau in brain size between 1.5 and 0.5 million years ago. WHY?

Answer 42

One hypothesis is that eventually the benefits of improving diet
no longer offset the costs of increasing brain size

Question 43

So then what could have lead to the next burst in brain size?

Answer 43

One possibility is that this was due to intraspecies interactions

Question 44

what is intraspecies interactions

Answer 44

Basically, as population sizes started to increase
There was more competition for resources within a species Food, mates, good places to live, etc
And relatedly,
More cooperation and alliances between individuals
Social interactions became more complex and this required a bigger brain

Question 45

Does brain size really matter?

Answer 45

kind of
A larger brain can hold more cells, larger cells, and more connections between cells
Cells are larger when they hold more DNA
The human genome is pretty big, so it requires larger cells
Having more cells and connections allows for more complex behavior
Of course, while we assume that these changes in size are associated with changes in organization, we can’t tell that from fossils

Question 46

are bigger brains good for language

Answer 46

yes

Question 47

Did big brains produce complex social environments? Or did they result from those social interactions?

Answer 47

it is hard to determine because it is almost like the “what came first, the chicken or the egg” question

but current theories look like this;
Increased hunting/tool use –> increased brain size –> increased sociality/language
but the last two are not set in their order because we have to rely on just fossils

Question 48

what species is vocal learning found in

Answer 48

Found in very few species –humans

• -cetaceans (dolphins, whales) –hummingbirds, parrots –elephants
• -bats

Question 49

what does vocal learning require

Answer 49

Requires sensory input
–young animals need to hear examples of the sound –if the don’t they will produce abnormal sounds
and Requires practice
–young animals have to try to make the sound many times before they get it right –they have to be able to hear themselves while they do it
–if they can’t hear, they will produce abnormal sounds

Question 50

what brain area is important of vocal learning

Answer 50

The brain areas (like the basal ganglia) that are important for this sort of learning are similar across species
And similar to brain areas that you need for learning other “motor” tasks
e.g. how to throw a ball, how to run or swim or kick, etc

Question 51

How better can we define language? And is it a specifically human trait?

Answer 51

Referential signaling Displacement Syntax

Productivity

Question 52

what is Referential Signaling

Answer 52

Signals can contain information
Chickadees can use referential signaling
They can indicate the size as well as how dangerous a predator is by changing the number of ‘D’ notes in their calls

Question 53

what other animal uses referential signaling

Answer 53

Vervet Monkeys

Question 54

how do Vervet Monkeys use referential signaling

Answer 54

Live in close-knit social groups or tribes
Have different sounds for different types of predators

Have different sounds for different types of predators
Snakes
–when someone makes the snake call, everyone looks down, and stands up bipedally
Hawks
–when someone makes the hawk call, everyone looks up and runs for the nearest bush
Leopards
–when someone makes the leopard call, everyone checks the trees and ground, runs out onto branches that can’t support the leopard’s weight
You can get the vervets to respond by playing back the calls
–so it’s not that everyone sees the predator and therefore knows what to do the information is in the call itself

Young vervets don’t know where to look at first
Adults don’t trust young vervets (often get their “vocabulary” confused)
–will wait for another adult to call
Young vervets have to learn from adults WHEN to make the calls and WHAT the calls reference or mean

Question 55

is referential signalling language

Answer 55

Not really

Question 56

why isn’t referential signalling language

Answer 56

With language, we can talk about things that happen at a different time
–the future, the past
This is known as DISPLACEMENT
Vervet alarm calls are only used to sound the alarm
–calls not produced when predator is absent, i.e. they don’t chat about the
predator after the fact
–whenever they hear the call, they respond by looking for the predator or hiding

Question 57

Where else might we find language

Answer 57

bees

Question 58

how do bees content for language-users

Answer 58

Bees perform a “waggle dance” to indicate where a good food source is (the rest of the video is here http://youtu.be/bFDGPgXtK-U)
Through this dance, they can communicate where they came across a good food source as well as how good the food was
So their communication has DISPLACEMENT, but is it a language

Question 59

what is Syntax

Answer 59

There are rules or principles governing the structure or sequence of communication signals
Once you know the rules, you can change the content
–i.e. once you know the rules for making a sentence in English, you can make all kinds of sentences with different words and meanings, following the same structure

Question 60

how do bees use Syntax

Answer 60

The waggle dance has a clear structure or syntax
–parts of the dance can be modified to indicate different information (distance, direction) –perhaps not as flexible as our language, but it does have a modifiable sequential structure

Question 61

what is Productivity

Answer 61

we can make new signals out of existing signals
– means that language isn’t finite but can increase to incorporate new things
Without this ability, we would have much more difficulty talking about all kinds of things today (everything from airplanes to the internet)

Question 62

how do bees use productivity

Answer 62

they don’t

Bees
Bees perform a “waggle dance” to indicate where a good food source is
Productivity
– we can make new signals out of existing signals
– means that language isn’t finite but can increase to incorporate new things
Without this ability, we would have much more difficulty talking about all kinds of things today (everything from airplanes to the internet)
The

Question 63

language involves or allows for what

Answer 63

displacement
syntax
productivity

Question 64

define Displacement:

Answer 64

the ability to talk about something temporally or spatially distant

Question 65

define Syntax:

Answer 65

a detailed structure or sequence that has rules and allows

Question 66

define Productivity:

Answer 66

the creation of new signals

Question 67

Our examples so far indicate that no other species possesses language But, could other species evolve language

Answer 67

Sure!
On the one hand, the sequence of environmental factors, mutations, etc that lead to human language seem unique and rare
But at the same time, there are many examples of really complex things evolving more than once
This is known as CONVERGENT EVOLUTION

Question 68

what are HOMOLOGOUS traits

Answer 68

are those that arise from a common ancestor

Question 69

what are ANALAGOUS traits

Answer 69

are those that are similar in function or structure, but not because they come from shared ancestry

Things that are analagous are said to evolve independently, that is, without a shared ancestor

Question 70

give an example of convergent evolution

Answer 70

common example that we talk about is wings Birds, bats and insects all have wings
but they all evolved them independently

common example that we talk about is wings Birds, bats and insects all have wings
but they all evolved them independently
We can see how different they are when we look closely at the structure
In addition, we can determine whether something is convergent by looking at the phylogeny

Question 71

what is Parsimony

Answer 71

is how you get a pattern of trait expression with the fewest changes

Question 72

In order to develop an eye, vertebrates require a gene called what

Answer 72

PAX6

Question 73

what is PAX6

Answer 73

PAX6 is a control gene

It regulates the expression of other genes in a cascade during development
In particular, PAX6 determines where an eye will develop
–if you put it on the leg of an embryo, the embryo will develop an eye there

Question 74

mutations in the PAX6 gene result in what

Answer 74

individuals with small (or no) eyes

Question 75

wherever PAX6 gets turned on or expressed, the embryo will…

Answer 75

eventually develop an eye

Question 76

What’s interesting is that even though eyes are examples of convergent evolution (they did not arise from a common ancestor)
what does this mean

Answer 76

Every time a species goes to make or evolve an eye, it uses that PAX6 gene

Question 77

What does the evolution of eyes have to do with language

Answer 77

In 2001, the gene FOXP2 was implicated in a speech and language disorder affecting half of the members of a particular family
It was hailed as the “language” gene and the hunt was on to find out more about it
1) Just in humans?
No. it turns out that FOXP2, like PAX6, is an ancient control gene, found in a wide array of species
–But, maybe FOXP2 works like PAX6 and could allow the convergent evolution of language in other species?
In songbirds, FOXP2 deficits result in poor song learning, and the production of aberrant, garbled songs
This implies it might be important for vocal learning

Question 78

if not just humans,, then what

Answer 78

What does the evolution of eyes have to do with language?
In 2001, the gene FOXP2 was implicated in a speech and language disorder affecting half of the members of a particular family
It was hailed as the “language” gene and the hunt was on to find out more about it
1) Not just in humans
2) Important for vocal learning?
Knocking it out in mice affected pup alarm calls (which are vocalizations). But, it also resulted in poor motor learning and motor ability
In bats, it may be important for echolocation, which requires a lot of sensory-motor integration but isn’t a learned vocalization

Question 79

is the evolution of eye Important for vocal learning

Answer 79

May be important for motor learning

But doesn’t appear to be a “language” gene

Question 80

Could other species evolve language

Answer 80

Sure!
On the one hand, the sequence of environmental factors, mutations, etc that lead to human language seem unique and rare, but there are lots of complex traits and behaviors out there, some of them are convergent
But, from current data, it doesn’t seem to have happened yet

Question 81

give a summary of all that has been discussed

Answer 81

Over the past 5 million years, humans diverged from a more ape-like ancestor
Multiple different human species have existed, each displaying differences in posture, brain size, and behavior
We discussed what would be necessary for those changes in brain size and behavior, as well as what those changes would be useful for
Then we talked about one of the traits that we consider uniquely human, language, and how it compares to communication systems in other species
–convergent evolution
–referential signalling, vocal learning, etc.