Revision cards

Question 1

Explain Darwinian evolution.

Answer 1

More individuals of a species are produced that can be supported by the available resources. Characteristics that allow for individuals to compete for successfully for these resources tend to increase in frequency as a result, populations of organisms change over time.

Question 2

Summarise 3 features essential to Darwinian evolution.

Answer 2

Competition
Variation
Adaptation

Question 3

How are patterns of diversity on archipelagoes more consistent with a theory of evolution than with a theory of special creation?

Answer 3

Archipelago species strongly resemble species found on the nearest mainland.

Question 4

Early estimates of the Earth’s age initially where inconsistent with natural selection being the mechanism behind evolution. How?

Answer 4

Estimates that underestimated the age of the Earth meant that descent with modification appeared to be too slow a process to explain observed biodiversity.

Question 5

What is the best estimate of the Earth’s age?

Answer 5

4.6 billion years old.

Question 6

What can be used to give an estimate of an absolute age of a fossil and how does it work?

Answer 6

Radiometric dating techniques look at the ratio of unstable isotopes to the more stable elements they would decay into and use the half life of the former to calculate time passed.

Question 7

Fossils can indicate behavioral traits of an animal. Give 2 examples.

Answer 7

Fossilized footprints indicate locomotor patterns

Dental records suggest feeding behaviour

Question 8

How does fossil restoration work?

Answer 8

Scars on the bones from muscle attachments and knowledge of general muscle anatomy allows for the creation of a general body shape.

Question 9

What is the difference between interspecific competition and intraspecific competition?

Answer 9

Interspecific is competition between differing species

intraspecific is competition within the species.

Question 10

What is the between an organism’s realized niche and their fundamental niche?

Answer 10

An organism’s realized niche is the portion of its fundamental niche that it actually utilizes

Question 11

Evolution occurs through descent with modification, how is this seen within the fossil record?

Answer 11

Fossils of simple organisms generally appear in the geological record before fossils of complex organisms.

Question 12

Farmer’s and stockbreeder’s employed aspects of Darwinian evolution before it was formerly conceptualised. What four ‘rules of thumb’ can be seen within their practical use of genetics?

Answer 12

Stable varieties (pure breds) nearly always breed true, pass down certain phenotypic traits.

You can mate two different parents to generate hybrids, which can be identical to one parent or combine features of both parents. Hybrid x hybrid crosses result in extreme variation in offspring and hybrids don’t breed true

Occasional mutations (sports) even in stable varieties.

Sports can be backcrossed with normals to create new stable varieties

Question 13

Give and explain 5 proofs that species are not immutable, and then also give a 6th point that can be used to as evidence of evolution.

Answer 13

Homologies: The presence of homologies/ homologous features, traits shared due to common ancestry. Some of the arteries, nerves, muscles, and bones we use to talk– and those we use to hear– correspond to gill structures in fish. This suggests that these gill structures evolved into our jaw arches.

Embryological similarities AND vestiges: All vertebrates share conserved stages of ontogeny which causes embryological similarity. These organism all pass through stages in which gill slits, an example of a vestigial trait, is present before diverging toward different adult morphologies. Moreover, vestigial organs in general are evincive of evolution.

Fossil record: The presence of transitional fossils.

Animal distribution patterns: Animals move about and are not fixed to a given area.

AND, Apparent functionality of animal structure:
Particular features and phenotypes are beneficial within a particular environment. We can see further evidence of this through how convergent evolution gives rise to analogous features in through the presence of similar selective pressures.

Question 14

What is atavism?

Answer 14

The presence of ancestral features e.g humans with tails

Question 15

How does artificial selection differ from natural selection?

Answer 15

Artificial selection is human intervened for the production of traits beneficial to us.

Question 16

What is evolutionary fitness?

Answer 16

An individual’s lifetime reproductive success relative to that of others in the population.

Question 17

Does selection pressure act on the genotype or phenotype?

Answer 17

Phenotype.

Question 18

Why are certain traits sexually selected?

Answer 18

They are often indicators of a male’s health or overall quality as a mate.

Question 19

What is sexual dimorphism?

Answer 19

The distinct presence of secondary sexual characteristics and other non genitalia based physical differences.

Question 20

When is sexual dimorphism more likely to be present?

Answer 20

When there are higher levels of completion for mates amongst members of the same sex.

Question 21

What is Allen’s rule, and what does its application to other members of Homo (in reference to modern day humans) allow us to infer about their lifestyles and habitats.

Answer 21

The morphologies of organisms have a tendency to become relatively shorter and squatter as latitude increases. Through this, we can see:

1) H. Neanderthal have a similar morphology to that of modern day inuits, we can see they have squat features that suggest they were cold adapted and lived in high latitudes.
2) H. Erectus have a similar (but smaller) morphology top the Masai, there long thin frames suggests they were adapted to the low latitudes of East Africa.

Question 22

Allopatric, Peripatric and Parapatric speciation are all similar forms of speciation, what are they and how do they differ?

Answer 22

Allopatric speciation is the process of reproductive isolation caused by geographic separation. E.g. same species on neighbouring islands with different climatic conditions.

Similarly, Peripatric speciation occurs when one of these populations is much smaller, said smaller population is geographically isolated at the edge of a larger population leading to speciation.

Parapatric occurs due to incomplete geographic separation e.g. same species moves to different climate zone on same island. Gene flow occurs unequally and, over time, reproductive isolation occurs upon the formation of a hybrid zone ala ring species.

Question 23

What is sympatric speciation?

Answer 23

Block to gene flow within same population, due to factors other than geographic causes.
Polymorphisms develop because of reproductive preferences (egg laying sites, differing mating behaviours etc) or other such isolating mechanisms that can occur within the sam physical population.

Question 24

What is the founder effect and what form of speciation is it most similar to?

Answer 24

The founder effect is when a few colonists found a new, isolated population, wherein there phenotype and genotype is not necessarily representative of the variation in the source population. It is similar to peripatric isolation.

Question 25

When did Ancestors of Homo diverge from other great apes?

Answer 25

Ancestral line diverged into species that gave rise to humans, chimpanzees and bonobos between 4.5 and 6 million years (myr) ago. Gorilla lineage split from that ancestral line 6-8 million years ago.

Question 26

When did our ancestors become recognizably human like?

Answer 26

Approximately 2 million years ago.

Question 27

When did modern humans emerge?

Answer 27

100-150 kya.

Question 28

What was the first species to leave Africa?

Answer 28

Homo Erectus

Question 29

What evidence do we have regarding the “out of africa” hypothesis?

Answer 29

Fossil record
Genetic analysis
Parasites.

Question 30

How does molecular clock dating work and what information does the analysis of gene flow tell us about Homo evolution after humans left Africa?

Answer 30

Assuming that neutral changes in the DNA code occur at a constant rate (as they are advantages or harmful), we can estimate the timescale in which changes occur by examining differences. Modern human migration out of Africa began about 150-100 kya (widely accepted dates approx 130-115 kya) with successive (and more significant) waves following at intervals after that.There were two episodes of limited gene flow: first, genetic admixture from Neanderthals to modern humans, shortly after the exit from Africa circa 50,000–60,000 years ago; second, subsequent admixture with the archaic population exemplified by the nuclear DNA extracted from the Denisovan finger bone. This second event seems to affect only the ancestors of present-day Melanesians, who are thought to have colonized Papua New Guinea some 45,000 years ago.

Question 31

Malaria is highly host specific, what does this indicate about human evolution and how does this conflict with other accounts? How do lice species give a similar account?

Answer 31

he parasite that causes malaria in Humans is most closely related to that which causes infections in Western Gorilla populations. This suggests that a single transmission event occurred between 7mya- 300kya in the congo basin. This data predates the emergence of Modern humans, this can be seen to contradict fossil record data that humans emerged first in East africa. Similarly, Clothing/body lice are more genetically similarly to Head lice than the latter is to pubic lice, suggesting that humans and gorillas inhabited the same areas.

Question 32

What does genetic evidence say about the presence of tapeworms in humans and how does this differ from traditional accounts?

Answer 32

Genetic evidence says tapeworms infection began with early hominids and the emergence of meat eating, it is thus most likely that when dogs were infected with tapeworms in the last 10,000 years that we past it to them.

Question 33

Ancestral humans left Africa in multiple waves, how has this affected the genes present in modern humans?

Answer 33

During the last migration modern humans interbred with Neanderthals and Denisovans .As a result there are varying degrees of admixture, especially north of the Sahara. In such areas (Eurasia), 1-6% of the human genome is Neanderthal and Melanesians have 4-6% of the genome shared with Denisovans.

Question 34

What does our diet allow us to infer about our ancestry?

Answer 34

There are substances our bodies cannot do without but we do not produce ourselves, which therefore must come from our diet (and thus also informs us about habitats and behaviour):

Vitamin C - Fruit. Suggestive of forests

N-3 fatty acids and Iodine- Fish. Gives credence to AAT

B vitamins- meat. Indicates are early role as carrion scavengers

Question 35

There are chromosomal differences between us and other apes, what does the structure of chromosomes indicate about our evolutionary history?

Answer 35

Chromosomes have multiple different regions, including two “telomeres,” structures at the end of each chromosome that contain repetitive DNA and serve as a protective “cap,” and one centromere, a region that binds together chromosome pairs during cell division. Chromosome pair 2 has telomere sequences in the middle of the chromosome and two centromeres indicating that it is the product of the fusing of two ancestral chromosomes

Question 36

What do differences in our teeth relative to other apes indicate about our evolutionary past?

Answer 36

Hominid dental system is small relative to apes and has decreased in size over evolutionary time. This suggests dietary change, specifically increased processing of food. Tool use and eventually fire.

Question 37

Humans are not the only animals to use tools, give other examples and how said animals use them:

Answer 37

New Caledonian crows use twigs to get insects in trees. If twigs are too long they will shorten them.

Wrasse crack shellfish on stones

Dolphins use a variety of different tools and have been shown to teach.

Question 38

When does the fossil record indicate that members of the Homo genus were tool users? When does it indicate that Humans where tool users?

Answer 38

Homo: Early pleistocene. Human: Upper paleolithic (40,000 to 8,000kya)

Question 39

Describe how bipedal locomotion is characterised by through its alterations upon our evolutionary morphology, as well as how these changes are beneficial.

Answer 39

1) Position of foramen magnum , laterally lines up so that the the spine connects to the base of the the skull rather than at the back.
2) S curved spine, as a consequence the vertebrae are wedged shaped and position the torso above the hips.
3) Bowl shaped pelvis moves the Knees more in inline with the midline of the body and feet become more arched rather than handlike (like other apes).
4) Change of musculature in consequence of humans becoming fully bipedal.

Bipedalism is more energy efficient than quadrupedal gaits. Changes in Pelvis/ Buttocks and Calves/feet are a consequence of humans becoming fully bipedal and evidence of our endurance running past.

Question 40

Describe what advantages bipedalism has for predator/prey interactions:

Answer 40

Our ancestors would have been better able to scan the horizons looking for food and avoiding predators.

Gives the appearance of looking larger, intimidation against predators.

Free hands for tool use.

Question 41

How have adaptations in our morphology also been detrimental?

Answer 41

Our increased brain capacity and shrinking hips due to bipedalism makes birthing dangerous.

Question 42

Why are there differences in Human skin colour moving away from the Afrotropics?

Answer 42

Skin colour is determined by the prevalence of Melanin which is used to protect organisms from UV. However UV also aids in the production of Vitamin D, humans move away from the equator, human skin colour lights so that they an absorb sufficient levels of UV to produce vitamin D as the levels of UV are not intense enough to be significantly dangerous.

Question 43

Explain the most widely accepted view the development of human morphology and behaviour.

Answer 43

As climate change incurred and the jungles human predecessors once inhabited started to shrink, some of them were forced out through competition and lived in the open plain.

Having to hunt and also avoid predation, bipedalism was selected for. Fossil evidence suggests that this may be vestigial of partial bipedalism in their arboreal life.

Speech and intelligence evolved from a need to work in groups to hunt and avoid being hunted.

Because it was so hot out there, they shed their hair to enable sweat to flow freely .

Question 44

What counterpoints does the aquatic ape hypothesis make about our evolution?

Answer 44

AAT argues that Humans inhabited Rainforests and would have to wade through mud/ occasional swim, this would eventually dry out into the savannah and many of the adaptations from there waterside life were able to be repurposed.

Bipediablism adapted from wading behaviour, we can see this in similar behaviour in other great apes as well as the fact morphological analogies in marine animals such as our spine and lower limbs in same plane

The development of speech may have been initially facilitated by water related breath control

AAT proposes that our hairlessness is more analogous to marine mammal hairlessness as if it were an adaptation to the savannah heat, why aren’t more savannah animals hairless?

Our reliance on N-3 fatty acids and Iodine which come from fish suggests we lived near water.

Question 45

The use of fire has been pivotal in driving our evolution but when does it go back to?

Answer 45

Though there are strong suggestions that Homo erectus was using gire 1.7 mya ago, definitive habitual use is date 790 kya and habitual cooking only 350 kya.

Question 46

What are some of the consequences of using fire?

Answer 46

Cooked food releases more energy and is easier to digest and it also kills pathogens. This may have helped facilitate the growth of our brains. This would also act to explain our relatively neotinic features as only small jaws, teeth and gut needed to process it. Moreover, Ash can be used to make soap, which again helps with pathogens.

Question 47

The human brain is pivotal to our success, how is it unique to other organism and how is it similar?

Answer 47

While we are not the only animals with large brains and our brains largely resembles a scaled up primates brain, we do have the largest EQ. Moreover, our brain is organised differently compared to other animals. Our neocortex is particular large relative to our size, we have the largest neuronal count per unit volume and we have a lot white matter. Other areas of our brain are much smaller relative in size compared to our neocortex and to other animals.

Question 48

What does EQ mean and how is it relevant to human intelligence?

Answer 48

EQ stands for Encephalization quotient, it is measure of brain to body ratio, taking into consideration the fact that some features of the brain remain consistently sized regardless of organism size. Humans have the largest EQ.

Question 49

What does the evolution of human facial morphology say about the development of our brain?

Answer 49

As our species evolved our face flattened relative to other related organisms as to accommodate for the expansion of our neocortex.

Question 50

Brains are energetically costly, what does this say about our evolution?

Answer 50

A high number of neurons requires energy levels that cannot practically be obtained from primate-type foraging, suggesting that cooking played a critical role in the development of our species by boosting energy provided by the food we did forage. However, some scientists argue that the development of more efficient tools sufficient in lowering the energy cost of food as larger brain size predates strong evidence of fire.

Question 51

What was Homo Sapien’s last common ancestor with Neanderthal and Denisovan man and what caused this speciation geographically?

Answer 51

H. Heidelbergensis; those that stayed in Africa when on to become Homo Sapien, while the Denisovan/ Neanderthal line diverged from populations that spread into Europe.

Question 52

Why is it unlikely that Human populations evolved independently?

Answer 52

The differences between human populations are relatively small.

Question 53

Could humans speciate in the future?

Answer 53

Technically yes if geographic or other pressures were to occur to cause a block to gene flows, however globalisation(as currently is) means this is unlikely, a more likely outcome is cultural convergence.

Question 54

What factor may cause barriers to gene flows in human populations?

Answer 54

Geographical distance, geographical barriers and cultural and language barriers.

Question 55

What are ornament displays and what do they signal?

Answer 55

Sexual selection characteristics, they indicate to potential mates the organism’s genetic quality; disease state and; freedom from developmental or environmental factors that may be deleterious to health quality.

Question 56

In terms of differences between Eastern and Western phenotypes, how has culture acted to change how emotions are typically read?

Answer 56

While Westerners typically distribute their expressions across their faces, Eastern populations emote with eyes. This affects where members of those particular racial groups fixate when reading emotions.

Question 57

Apes and Humans differ in emoting, how and why?

Answer 57

Humans are more eye-orientated than other greater apes, this is because Humans have a lighter scalar and the iris is relatively small in comparison. this adaptation evolved because of our social nature as the eye became a useful communication tool, this makes it easier for one individual to infer where another individual is looking, increasing the efficacy of this particular form of nonverbal communication.