ANT Flashcards
Definition of life history
history of the changes through which an organism passes in its development from birth to death.
Know the different stages of humans’ life history
Pre-natal life
birth
infancy
childhood
juvenile
puberty
adolescence
adulthood: reproductive stage
adulthood: senescence
Know that fitness is a function of survival and fertility
Know the definition of fitness
The ability of an organism to survive and reproduce in its environment, and to pass its genes on to the next generation
Know what happens to our cells during our life cycle (alternating haploid and diploid stages). Know how this relates to the number of chromosomes and pairs of chromosomes in each cell
diploid nucleus of sperm and ovum-producing cells go into meiosis where they become haploid nuclei, fertilization hits and results in a cell called the diploid nucleus of zygote, zygote has 23 pairs of chromosomes, half from maternal and half from paternal, the embryo and then the fetus, infant, will have 46 chromosomes
Know the definition of meiosis and mitosis, and be able to describe both types of cell division
Meiosis is the process leading one diploid cell to turn into 4 haploid cells
Mitosis is the division of a diploid (or haploid) cell that forms 2 identical cells that are also diploid (or haploid)
Know what cells are diploid and what cells are haploid in the human body
Gametes (sperm and egg) are haploid
The rest of our cells are diploids, in short somatic cells
Know in which organs spermatogenesis and oogenesis occur
Spermatogenesis occurs in the testes in the seminiferous tubules
Oogenesis occurs in the ovary
Know when female gametes are formed and what happens to all but 400 of them
Gametes are formed for females during oogenesis when in embryo development. All but 400 of them go under astresia during and after puberty
Define of spermatogonia
an undifferentiated male germ cell
Define oogonia
An immature female germ cell forming oocytes by repeated divisions
define primary spermatocyte
A diploid cell that contains two sets of chromosomes, one from the mother and one from the father, and is a developing male germ cell
Define secondary spermatocyte
a round cell that is produced when a primary spermatocyte divides during the first meiotic division
define spermatid
an immature male sex cell formed from a spermatocyte that can develop into a spermatozoon without further division
Define primary oocyte
an immature female gamete that has started the first stage of maturation, but has not yet completed it (a diploid cell that is arrested in the prophase stage of meiosis)
Define secondary oocyte
A cell that develops after a primary oocyte undergoes the first meiotic division, and is a precursor to the egg
define ovum (ova)
another name for an egg cell
define zygote
a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum
Know what happens to parental chromosomes during fertilization
They combine to form a new cell called the zygote
How many chromosomes are there in humans? How many pairs of chromosomes?
46 chromosomes and there are 23 pairs
Define DNA
Carrier of genetic information, it codes for complex molecules called proteins, it determines the phenotype of somebody.
Define histones
Basic proteins found in the nucleus of eukaryotic cells that bind to DNA, allowing it to be condensed to form the structure of chromosomes
Define nucleotides
a compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA
How many pairs of nucleotides are there in the human genome
3 billion pairs
Know there are 4 types of nucleotides in DNA
4 letters make DNA and that is adenine, guanine, cytosine, thymine
Know the DNA codes for proteins
Know the link between DNA and our phenotype
Know our phenotype is partially linked to our DNA and partially linked to our environment
What are mutations? How often do they occur? Can you name 3 types of mutations?
A change in the DNA sequence of an organism, they occur 1.1-1.7*10^(-8) which makes them rare, substitution, deletion, insertion
Are mutations generally neutral? Beneficial? Deleterious?
most are neutral or deleterious, beneficial mutations are rare
How many mutations can we expect to find, approximately, by comparing your DNA to the DNA of your biological parents?
around 30-50 mutations
Be able to explain how genetic drift works
a random change in the frequency of alleles within a population over time, occurring due to chance events and not related to natural selection
Know the roles played by mutation, migration and genetic drift in evolution
Mutation acts as the primary source of new genetic variation by introducing changes in DNA sequence, while migration (gene flow) transfers genetic variations between populations, and genetic drift randomly alters allele frequencies within a population due to chance events, essentially causing changes in the genetic makeup of a population over time without any selective pressure
What is a gene? An allele?
A sequence of DNA that give physical characteristics by synthesizing proteins. An allele is a variant form of a gene, or one of two or more alternative versions of a genetic sequence due to mutation
Be able to explain natural selection
A mechanism of evolution that explains how organisms adapt to their environment over time. Variation within a population, heritability of traits, differential reproductive success
What happens when a deleterious mutation occurs
It will decrease the individual’s fitness
Describe the evolution of lactase persistence
Digesting milk requires producing an enzyme called “lactase”. High frequencies of lactase persistence alleles are found in regions where milk is traditionally produced. Lactase persistence alleles increased in frequency due to natural selection. Milk allowed lactase persistence carriers to have moe energy and proteins in their diet. This allowed for a slightly better survival, and maybe also to reproduce more. More offspring means an increase inheritability of this trait of lactase persistence
Remember the main 4 processes responsible for genetic evolution: mutation, migration, genetic drift, natural selection
Who was Charles Darwin? When did he live?
Charles Darwin discovered evolution. He lived from 1809-1882
Name some of the phenotypic characteristics that have evolved through natural selection and allow just us to walk bipedally
A flattened and flared pelvis
Neck of femur is lengthened
Cortical bone of neck of femur is thicker on its lower edge
Knees close to the centerline of the body
Name some key human adaptations that are transferred genetically or culturally
Large brain, stone flaking, fire control, consumption of meat, hunting, scavenging, language, cultural diversity, technological innovation
How old is our planet? When did life appear?
Earth appeared 4.5 billion years ago. Life appeared 3.8 billion years ago
When did the Hominin branch split from the branch leading to the extent of chimpanzees and bonobos?
Between 5 and 7 million years ago
What makes evolution happen faster or slower?
It is fast when there is a lot of variability on the phenotypic trait under selection
When the trait is highly inheritable
When the coefficient of selection is high (relationship between trait and value and fitness is strong)
It is slow when the population is small and has limited genetic diversity
Know the difference between directional selection, disruptive selection, and stabilizing selection
Directional selection favors one extreme phenotype, disruptive selection favors both extreme phenotypes, and stabilizing selection favors the intermediate phenotype, essentially selecting against the extremes
What is maladaptation? Be able to explain why cetaceans can’t breathe underwater
Failure to adjust adequately to the environment or situation. Cetaceans have a terrestrial common ancestor, which itself evolved from an aquatic ancestor. Gills were present in the ancestors of all, but disappeared in a group that became adapted to terrestrial life, replaced with lungs. The ancestors of cetaceans evolved adaptations to aquatic life again, but there was no evolutionary path towards evolving gills again. They ended up adapting to breath holding
What maladaptations do humans have? What constraints cause these maladaptations?
We cannot fly, we cannot digest cellulose, we develop addictions, we struggle with long-term adaptation. The constraints are that life has limitations, genetic evolution is slow, environments can change fast, genetic evolution proceeds small step by step because most mutations have small effects, there are trade-offs between traits
Why does infanticide occur in langurs?
It is a reproductive strategy where a new male taking over a group kills infants that are not his own, allowing the females to become fertile faster and mate with him, increasing his reproductive success
Explain why altruism looks like a maladaptation, but is actually an adaptation
altruism is recognized as an evolutionary adaptation because it enhances the overall fitness of individuals indirectly
Be able to explain Hamilton’s rule
Altruism will be favored if the benefits to the recipient * coefficient of relatedness is greater than the cost to the person paying the price
What is the coefficient of relatedness between a mother and one of her children?
1/2
What is the coefficient of relatedness between 2 full siblings? Between 2 half-siblings?
1/2, 1/4
Be able to explain the “two-fold cost of males”
the theoretical disadvantage that sexually reproducing populations face compared to asexual populations
What is parthenogenesis?
reproduction from an ovum without fertilization
Explain inter-chromosomal and intra-chromosomal recombination
Inter-chromosomal is when the exchange of genetic material between different chromosomes occurs during meiosis with a random assortment of alleles. Intra-chromosomal recombination is when genetic material is exchanged with bits from different locations on the same chromosome.
Define “crossover”
the exchange of genetic material between two homologous chromosomes during meiosis, where segments of DNA are swapped, resulting in new combinations of alleles and contributing to genetic diversity in offspring
Know the 4 reasons why sexual reproduction is advantageous even if producing males costs mothers a lot of resources
When selection pressures change over time
When selection pressures change over space
When organisms that are less adapted to their environment can opt to reproduce sexually
When population size is smaller
What is our species’ scientific name?
Homo sapiens
Know how related we are to chimpanzees, bonobos, gorillas, orangutans
Homo sapiens belong to the family Hominidae (Hominids in English). This in short means we belong to a common ancestor, called the “great ape”
Comparing human and chimpanzee life history, what differences do we see?
- Humans have an exceptionally long lifespan
- Dependence of human juveniles on older individuals
- Support of old, post-reproductive individuals (females in particular) to younger individuals in humans only
- Human males provision females and juveniles
Define “life history trade-off”
a situation in biology where an organism must allocate limited resources between different life history traits
Why do fruit flies exposed to a high extrinsic mortality evolve a higher intrinsic mortality?
Higher mortality means less chance of survival, this allows the fruit flies to allocate fewer resources into survival and allocate more to reproduction
Why is evolving a longer lifespan “expensive”?
- thermoregulation, running away from predators
- repairing damaged cells, fixing damaged DNA, fighting pathogens
- Having a large but slow maturing brain, having a large body increase our development time buy delays reproduction
in short it requires a lot of energy
Why is evolving a greater fertility “expensive”?
- Producing gametes requires energy and time, especially in women, who produce larger gametes than men
- Searching for a partner, learning communication and other culturally important skills that help finding a partner, buying gifts, outcompeting same-sex individuals
- mating, investing energy and health capital during pregnancy, producing milk, caring for offspring requires energy and time that could be allocated to improve our survival
(In short requires a lot of energy)
What types of resources are involved in life history trade-offs?
Energy, time, and nutrients
Why is the average interbirth interval observed in women generally greater than 24 months, while it could in theory be as low as 12-15 months?
the evolutionary pressures favoring maternal recovery, child survival, and reproductive success result in naturally longer interbirth intervals. Both biological mechanisms, such as hormonal regulation during lactation, and ecological factors, such as resource availability and cultural practices influence these intervals. This extended spacing reflects an adaptive strategy to optimize both maternal and offspring fitness in the long term.
Define the demographic transition
the shift from high birth and death rates to low birth and death rates that typically accompanies socioeconomic and cultural changes, particularly during the transition from pre-industrial to industrialized societies.
Know the characteristics of the 0-6mo development stage
- Starts noticing sounds
- Starts vocalizing. Chuckles and laughs
- Starts reaching for objects with either hands
- Still struggles transferring objects
Diet: 100% milk
Know the characteristics of the 6-12mo development stage
- Starts crawling, and then bipedal walking around 12mo
- starts saying simple words. “Agua”, “Mama”, “Dada”, “dog”
- Listens and understands simple words
- Starts using fingers. Uses opposable thumbs and index finger to pick things up
- Moves objects, places them in container
- Starts eating solid food
Know the characteristics of the 12-24mo development stage
- Uses words for most things
- Uses several words, mini sentences, to comment or ask
- Uses crayons, starts drawing
- Can turn book pages
- Walks well
- Typical weaning period
Know the characteristics of the 24-36mo development stage
- Starts making proper sentences with 4+ words
- Uses several words, mini sentences, to comment or ask
- Enjoys listening to stories
- Socializes with other children
- Able to draw circles
Know the characteristics of the 36-48mo development stage
- Talks about activities, says what happened at (pre)school
- Answers questions specifically (what, where, who, why?)
- Able to dress almost independently. Still struggles with buttons and shoe laces
- Enjoys socializing with other children
How does time to walking onset vary in relation to brain mass in mammals?
This is because larger brain mass often correlates with slower brain maturation, as neural networks take longer to develop the complexity required for motor coordination and other cognitive functions.
What parental behavior affects the timing of development milestones?
Physical interaction and stimulation, nutritional practices, cultural norms, verbal and social interaction, alloparental care, risk aversion and protective practices, evolutionary and cultural context
What is kitwalse (making jump)? Where do Kipsigis live?
In Kenya, mothers stand children in their laps and bounce them vigorously in a routine the Kenyan Kipsigis call “kitwalse,” meaning “to make jump”. The child responds with stepping movements, sometimes “walking” up the adult’s body. They live Western Highlands of Kenya
Why to Ache children walk on average a year after most other children? Where to Ache people live?
The Ache, a foraging society of Eastern Paraguay, travel for extended trips through uncleared, dangerous forests. For fear that children will “get into trouble” in the forest, mothers rarely put their infants down or let them venture more than a meter away. Locomotor development is severely delayed in the Ache
Read and understand some of the specificities of childrearing in Teso people, Kipsigis, Ache, Jamaicans
Kipsigis mothers of Kenya do not give infants opportunities to crawl, and their onset age is delayed
Ache fear children getting lost so they don’t let them walk
Some Jamaican mothers continue to practice massage and formal exercise of sitting and walking after immigrating to England, but others do not
Know the definition of the Theory of mind (ToM)
the ability to attribute mental states to ourselves and others, serving as foundational elements for social interaction
Know how the Sally and Anne test works
Sally put ball in carriage, Anne takes and puts the ball in the box, where does Sally look?
At what age do children start developing a ToM, on average
4-5 years old
Understand the Eurasian Jay experiment in class (about ToM)
Understand the Chimpanzee experiment mentioned in class (about ToM)
Understand the difference between general growth and growth velocity
General growth describes what is achieved (e.g., adult height), while growth velocity explains how it is achieved (e.g., timing and pace of growth spurts)
Know the shape of the growth velocity curve in mice and cows
It goes high up and then goes down drastically for mice and for cows it is yeah, what you expect for a big animal
Know the shape of the growth velocity curve in humans, and know when a growth spurt is observed
Goes up and up slowly, growth spurt starts way high up and goes down with a bump up at 10-16 then goes back down
Define the Juvenile stage
Offspring who are weaned, no longer dependent on maternal lactation for feeding, but who are still prepubertal
