LO5 - Human Evolution and Genetics Flashcards
Nature
This links to the idea of nativism - everything we know about the world is innate and genetic. It is this that determines behaviour.
Nurture
This links to empiricism - we are born with a tabula rasa and nothing in terms of behaviour and knowledge is inherited. Everything is learned.
Our past experiences determine individual differences.
Interactionism
We are born with some behaviours but our experiences can influence our behaviour and how it is expressed in the future. Experiences can also change which innate behaviours are expressed.
What is expressed in the future is based on the interaction between nature and nurture.
Nativism
Most of the knowledge we have is innate (view held by Descartes) and we are born with it. It is this alone that determines out behaviour.
It is associated with the nature side of the debate and genetics. We can look at genetics and inherited characteristics to explain behaviour.
Empiricism
We are born as a blank slate with no innate behavioural knowledge. Everything we know is learnt.
Watson and Locke held this view. It is associated with nurture. We need to look at a child’s individual history to understand their behaviour.
Proximate causation
The close causes: these are the things related to the internal changes of an animal such as hormonal state, learning and experiences.
This explains how an animal produces a behaviour and takes a reductionist approach.
Ultimate causation
This is related to evolutionary causes of behaviour (why an animal behaves the way it does).
Functionalism is interested in this question.
Species
A group of animals that can mate, do mate and produce fertile offspring.
Genus
A group of species that have evolved from a common ancestor
Family
All of the genera that originate from the same ancestor.
Homo Erectus
This was the first from our genus that left Africa. They were very conservative and used the same tools. They didn’t have the flexibility and development of culture that Homo Sapiens have.
While it could create tools, it could not adapt in the same way.
Homo neandertahlensis
Another species within our genus. The migrated out of Africa in a different route to Homo Erectus.
Their DNA is found in modern humans (mostly Asians and Europeans).
They mated with Homo Sapiens at some point.
Homo Sapiens
This is our species. We used to coexist with other Homo species.
What differentiates us is our large brain. We are a young species but had the most flexible culture which showed the most development.
We also moved out of Africa. Our increased brain size sparked the cognitive revolution.
Out of Africa Hypothesis
We came from Africa. The first Homo genus were born there and from there we left and explored the planet.
Homo Erectus was the first to explore the planet and entered Europe and Asia.
Multi-regional hypothesis
This is the idea of several migratory waves out of Africa. Includes the different routes that the different species within Homo genus took.
Another group of Homo evolves from the earlier group and continues to migrate.
It is not simply in Africa that humans evolved.
Cognitive revolution
This is characterised by the explosion in brain size that distinguishes us from our ancestors.
Humans have cultural abilities, lifestyles and interactions that Homo Erectus was not capable of because of brain size.
The brain is an enormous energy sink and the size of it is the result of a random nutation in one gene.
Consequences of the cognitive revolution
We have to spend more time looking for food to feed our brain.
Humans are born prematurely because of our skull size. Babies are very plastic and are helpless for a long time.
Raising children is a shared responsibility. We cook with fire which increases the nutritional density of food.
Language is far more complex. Helps us survive by communicating, planning etc.
Language also lets us talk about theories and allows for rapid innovation.
Agricultural revolution
Around 8000 years ago, hunter-gatherers settled down and agriculture emerged and animals were domesticated.
We discovered food grew from seeds and animals could be tamed. Shift in culture occurred. We required permanent houses near our crops.
Consequences of agricultural revolution
Ownership as a concept emerged. You protect the things you think are yours.
Larger societal structures emerged e.g. villages/cities. We are not adapted to this.
Diet changes - it got worse as we only eat the crop we grow. Cohabitation with animals resulted in disease.
Loss of knowledge - in one generation all nomadic knowledge was lost.
We had to work harder - plants and animals require more labour.
Advantages of the agricultural revolution
We could have more children at once. This was also needed to look after the crops.
No need to carry children around. It didn’t matter so much when one child dies.
Population grew a lot.
Scientific Revolution
We developed methods that allowed us to explore the nature of things. We are able to control nature to an extent and the introduction of science ensured our survival despite not being at the top of the food chain.
The Anthropocene
We are in a position now to modify the entire biosphere due to our knowledge and lifestyle. This may be the last phase if we are not cautious.
We have manipulated the planet so much that it may not be able to habitate us anymore.
Gene
Within each cell’s nucleus we have strands of genetic material (chromosomes) which contain DNA which is used to express certain traits.
DNA produces nRNA which codes the building block proteins of an organism. DNA contains all the genes that low a cell to function.
Chromosomes
46 chromosomes contain all of our genetic material. Each cell contains many mitochondria that contain their own DNA meaning there is more than one set of genetic material in each cell.
Our chromosomes look similar to chimps but other organisms have far more pairs - the number does not relate to advanced development.
Diploid set
We have 23 pairs of chromosomes which makes up a diploid set.
Normal human cells contain 23 pairs of chromosomes
Haploid set
The sex cells of a human have a haploid set of chromosomes (only 23). They don’t have pairs.
Two combined haploid sets produce a diploid set in the offspring which allows us to inherit traits from both parental lines.
Genotype
The complete set of an organisms genes
Phenotype
The overt characteristic of an organism (properties we can observe resulting from what genes are expressed).
Phenotype is a product of genotype and environmental factors and experience.
Nucleus
Within a cells nucleus is the genetic material.
Prokaryotic cells have no nucleus, only Eukaryotic cells (plant and animal cells) have a nucleus.
Allele
These are different forms of the same gene.
We inherit a combination of features from our parents (two sets of genetic coding). These different forms can be called alleles and can either be hetero or homo zygous.
Heterozygous
The alleles code for different phenotypes. The expressed phenotype reflects the coding in the dominant gene.
Homozygous
The alleles code for the same phenotype.
Innate human characteristics
What are we born with? These are phylogenetically preserved behaviours across the species. E.g. Baby Schema.
Baby Schema
It is the reaction to a specific set of facial characteristics that adults express.
Human babies have: large heads, round faces, large eyes and a small mouth and nose.
This causes adults to carry out caretaking behaviours as these characteristics have a high appeal to humans as this induce a perception of cuteness.
Caretaking behaviours ensure the survival of infants.
Piloerection
This is hairs standing on end as a reaction to cold or a fight.
We see this behaviour in animals raising their hackles. This makes them look bigger.
When we are cold this occurs to create a layer of warm air between the skin and outside - it insulates.
Inborn preferences
There is a preference to seek cover (building forts and caves). As humans are not at the top of the food chain we like to hide.
Adult humans also prefer to fit in corners.
We also prefer higher looking for our dwellings as this is safer.
Inborn abilities (social)
Primates stretch out hands to initiate contact.
Body contact signals affection/caring. This is the same in all primates and is used to establish trust.
Behaviour of petting/caressing is primate behaviour of social grooming. Purpose of keeping clean.
Inborn abilities (facial expressions)
We share facial expressions with primates (grimacing). We have similar facial expressions with strong emotions as those of chimps.
Similar facial expressions allow us to conclude that others have the same inner state as us. We can only speculate - this is theory of mind.
Innate behaviours
These are not learnt but given to us through genetics. These are part of our species behavioural knowledge.
We have adapted to a hunter-gatherer lifestyle as this is what the majority of our ancestors did. Babies come with behaviours that promote their survival to this kind of lifestyle.
Inborn reflexes
These aid survival.
We also have an attraction to novelty which helps us to develop our knowledge of the world.
We have motivation to explore and manipulate objects.
Play behaviour simulates adult life.
We have basic cognitive skills e.g. numerical.
Moro reflex
The arms spread out then pull in then the infant starts to cry. This is present at birth and is a startle reflex associated with a loss of balance or support.
It is a survival reflex as the baby wants to cling to their mother. If they lose balance and try to grab their mother but they are not there, the baby will try to get its attention.
Grasping reflex
Infants can support their own weight with grasping. Mothers has fur and previously this would have been to attach the baby to its mother.
Feeding/Rooting reflex
If the corner of a baby’s mouth is touched, it turns towards the stroking and roots.
If the baby had to learn to feed this would be a risk for survival. It helps for breastfeeding.
Crying
Extremely efficient innate behaviour. It is well coordinated and high in energy consumption.
it is primal communication and ensures a caring reflex from parents as it is both worrying and irritating.
It activates the centre that promotes fear and adults try to rectify this as we want the sound to stop.
Laughing
It is innate as blind and deaf children still show it.
It is universally human and part of our social behaviour - it serves a purpose.
Trait
These are commonalities such as personality, emotion, sexual behaviour and reasoning that can be traces to evolution and natural selection.
Twin studies on heritability (interactionist findings)
Groups are created to examine the extent to which performance on IQ tests reflects the influence of inherited traits or environmental factors during development.
Monozygotic twins growing up together/apart
Dizygotic twins growing up together/apart
Normal siblings growing up together
Individuals not related to each other living apart (control)
Similarity in intelligence was highest in monozygotic twin who grew up together, then those who grew up apart, then dizygotic twins living together then siblings reared together.
Inheritability estimates for intelligence are around 40-50% in children and young people and 60-80% in adults.
Scores of adopted children correlate more with the scores of their biological compared to non-biological relatives.
Dizygotic twins
These come from two eggs being fertilised by two sperm.
They are two organisms with a different genetic makeup.
Monozygotic twins
They come from one sperm fertilising one egg the then the egg splitting to form two zygotes.
They are genetically identical.
Heritability
A statistical estimate of the proportion of variability in the population for some trait is attributable to genetic differences between the group
Natural Selection
Darwin’s theory of evolution has this at its core. Those organisms who are best adapted to their environment survive and have a better chance of reproducing.
These traits are delivered to the next generation and the number of adapted organisms increases.
Rapid multiplication
There are so many life forms that produce far more offspring than can actually survive.
There are random mutations in the genes of offspring compared to parents. Genetic material is not identical between parents and offspring. This generates variation.
Limited resources
Organisms must compete to get resources. An increase in population requires more resources (space and food). However, both are limited and often relatively constant. Individuals compete for these resources.
Humans may decide to be agriculturalists as it gave us some control over these limiting factors.
Struggle for existence
Occurs over limited resources but also available reproductive partners. It is both intraspecific and inter specific. All animals in a habitat compete for the resources.
It also plays out on the environmental level as individuals compete for space to live.
Symbiosis provides another view of this. Cooperation is seen.
Variation and mutation occurs (genetic material changes)
As the environment changes, the more genetic variation within a species, the more likely it is to adapt as it is more likely that a mutation will have occurred that increases the ability of the species to survive.
If environment changes but not changes occur in the organism, the species will go extinct as it cannot adapt.
Some traits in an individual allow them to adapt better to environment.
Survival of the fittest
Individuals with more adaptive traits will have higher probability of reproducing and passing on their genes. Natural selection acts on phenotype. Advantageous genes are passed on to the next generation.
Inheritance of useful variation allows for the formation of new species.
Endosymbiosis theory
This contests that the world is a fight for survival.
Previously, life has developed by one organism absorbing another and taking in the qualities of both organisms to form a new species.
Endosymbiosis is the process of cells living together. One organism lives inside another and cells stated to become highly complex as they were filled with chloroplasts and mitochondria.
Prokaryotes
These were the first living organisms - they were unicellular and had no membrane-bound organelles such as mitochondria/nucleus.
They have none of the basic features of plant and animal cells.
They had the ability to absorb other organisms by wrapping their cell membranes around them.
Eukaryotic cells
These are the plant and animal cells that we see today. They contain specialised organelles, some of which are membrane-bound.
For example mitochondria are an organelle with their own DNA. They reproduce themselves through binary fission.
Evidence for Symbiotic theory
Cells aren’t able to contain some of the structures within them e.g. mitochondria - they must have absorbed them.
Chloroplasts and mitochondria have their own DNA which is strikingly similar to that of bacteria. Ribosomes also have the same structure to that of ancient bacteria.
Two layers of membrane for these organelles suggest that the outer membrane used to belong to the cell that engulfed them.
Binary Fission
This is different to sexual reproduction as it only requires one bacterium to divide and reproduce.
DNA replicates itself then the cell splits in two, both of which containing identical DNA.
Consequences of endosymbiosis
Endosymbiosis can account for the origins of the vast variety of eukaryotic organisms.
Absorbing process allowed organisms to combine powerful abilities and become better adapted for life on earth. This resulted in the plants and animals we see on earth today.
Life as we see it now is the result more of cooperation than competition.
