B1 Non-lecture content FROM ESSAYS

Question 1

Stats for amount of shared DNA with chimpanzees

Answer 1

• Cohen (2007) ~98% shared
• Suntsova & Buzdin, 2020- human-specific single nucleotide alterations constituted just 1.23% of human DNA
• Kronenberg et al, 2018- humans and chimps share ~99% of our 20,000 genes, with only 40,000
• Yunis & Prakash, 1982- humans 46 chromosomes, chimpanzee 48

Question 2

Genome size definition

Answer 2

amount of DNA contained in a haploid genome expressed in terms of the number of base pairs (Brenner, 2013)

Question 3

citation for argument against genome size being responsible for human genetic uniqueness

Answer 3

Eddy (2012)- single-celled amoebae genomes up to 100-fold larger than human

Question 4

genetic regulation and expression cited definitions

Answer 4

• regulation- process of the controlling the timing, location and quantity of gene expression- achieved through a variety of regulatory proteins and chemical modification of DNA (Serge, 2023)
• expression- process by which the DNA sequence is used to direct the assembly of a protein molecule (Brody, 2023)

Question 5

further findings for likelihood of genetic human uniqueness being found in regulation including suggestion on process

Answer 5

• Vogt (2021)- use of hybrid induced pluripotent stem cells (iPS) combining human and chimp iPS cells- morphological difference between humans and chimpanzees arises from differences in gene regulation- including through the action of transcription factors
• Suntsova & Buzdin (2020)- changes in structural genes happen at the expression regulation level, which in turn causes larger alteration of gene regulation network- going on to cause molecular, anatomical, physiological and cognitive uniqueness

Question 6

Broad role of FOXP2 citation

Answer 6

• Spireti et al (2007)- broad regulatory role e.g. through regulating foetal brain development
• ‘human’ derived amino acid changing variants were also shared by Neanderthals (Maricic et al, 2013)

Question 7

Further genes involved in human brain development

Answer 7

• Johansson et al, 2021- ZNF558- expression modulated by variable number tandem repeats- differ across human and chimpanzee populations- ultimately causing differences in forebrain development

Question 8

Differences in timing of genetic expression unique to humans

Answer 8

• Neubert (2014)- the timing itself of gene expression also plays a role in contributing to the unique human neurological phenotype, particularly in prefrontal areas (an area associated with human uniqueness)

Question 9

role of gene-environment interaction in human uniqueness

Answer 9

• Ralston (2008)- environment role in expression
• Varki (2009)- genomic expression that contributes to unique human phenotypic characteristics is greatly dependent on an increasing dependence on learnt behaviour and culture through primate evolution
• Enard (2004)- epigenetic changes particularly impact promotor methylation in the brain of humans, more so than in chimpanzees
• that through genome interactions with environment, expression is affected, and this has potential to relax thresholds of what’s needed to create large-scale genomic and ultimately phenotypic diversity

Question 10

Adaptive mechanisms definition

Answer 10

strategies used by organisms to adjust to novel environments (Alexander, 2019)

Question 11

extreme environment definition

Answer 11

habitats with harsh environmental conditions which are beyond the optimal range for human development

Question 12

Hypoxia definition

Answer 12

lowering of atmospheric pressure (Chavala, 2018), which results in a severe lack of oxygen at tissue level that is insufficient for adequate homeostasis (Beenish et a, 2022)- typically above 2500m- challenge for human adaptation of presented due to the lowering of barometric pressure and consequently lower partial pressure of oxygen in the atmosphere (Moore, 2017)

Question 13

Outline short-term physiological acclimatisation, including definition/necessary conditions

Answer 13

• involves physiological, anatomical, or morphological adjustments to improve survival in response to environmental change (Demmig-Adams, 2008)
• Physiological viability across diverse and extreme environments necessitates a high degree of phenotypic plasticity (Wells & Stock, 2007)

Question 14

citations for short term acclimatisation to high altitude

Answer 14

• increase in breathing rate and depth, haemoconcentration via reduced plasma volume (Sharma, 2022)
• increased heart rate and cardiac output (Luo et al, 2014)
• homeostatic processes- reducing oxygen levels in blood can trigger several metabolic cascades, including an erythropoietin release from the kidneys stimulating red bone marrow, which in turn causes enhanced erythropoiesis to increase red blood cell count (Vizcardo-Galindo et al, 2020)- increases oxygen carrying ability of blood to compensate for hypoxia
• cerebral blood flow regulation systems are altered, and increased angiogenesis (the formation of new blood vessels) is prompted around the brain (Ainslie & Subudhi,2014)
• work by counteracting and compensating for lower ambient oxygen availability (Beall et al, 2012)

Question 15

citations for developmental adaptation to high altitude

Answer 15

• less immediate time scale (Beall, 2012)
• developmental environments may lead to the development of enlarged residual lung volume in adulthood (Frisancho, 2009), increase in vital capacity (Beall, 2012)
• contributes to the successful cardiovascular adaptation of native Andean and Tibetan populations, although there is variation between populations in the extent to which these developmental adaptations are present (Beall, 2012)- may be due to slightly different environmental nuances of these population’s surroundings, as well as the potential influence of the genome in constraining phenotypic plasticity (Chevin & Hoffman, 2017)

Question 16

citation to how developmental adaptation in extreme environments occurs/takes effect

Answer 16

when individuals develop in biologically stressful environments, phenotypic expression is greatly affected, and this can have lifelong effects (Frisancho, 2009)

Question 17

citations for genetic regulation at high altitude

Answer 17

• Beall (1998)- natural selection on haemoglobin concentration within Andean and Tibetan populations
• O’Brien et al (2020)- the EPAS1 locus has distinctively high allele frequencies at numerous SNPs as compared to populations not living in such high altitudes- effects effects haemoglobin concentration upon exposure to hypoxia (Beall, 2012)
• Beall (2012)- percentage of arterial haemoglobin that is saturated with oxygen- largely regulated by specific dominant allele- presence of at least one copy more common in Tibetans living at higher altitudes (84%), compared to those living at lower altitudes (78%) as results in less hypoxic stress- only in HA natives

Question 18

Citations for differential population genetic adaptation mechanisms at high altitude

Answer 18

• EPAS1 locus- under selection in Tibetan populations (Beall et al, 2012), but not in Andean (Bigham et al, 2010)
• Gao (2024)- adaptation at the population level is influenced by evolutionary forces that are population-specific e.g. demography, recombination, and unique environmental elements

Question 19

Citation for possibility cultural buffering of environmental extremes

Answer 19

enhance survival and efficiency when living in environmental extremes (Ilardo & Nielsen, 2018)

Question 20

human growth definitions, including defining normal growth

Answer 20

• irreversible and constant increase in size (Balasundaram, 2022)
• statistical definition of normal- z-score for length/height for age less than minus two standard deviations from median growth standard for children globally (WHO, 2017)

Question 21

abnormal growth prevalence statistic

Answer 21

• Vilcins (2018)- just under 1/4 children affected by stunting (impaired linear growth in the early years of life)

Question 22

genetic factors in normal growth citations

Answer 22

• Hall et al (2017)- Malawi twin study- gut microbiome was a strong predictor of growth outcomes following malnutrition
• Duggal et al, 2018- several genetic associations with protein and carbohydrate intake potential
• Onis & Branca (2016)- epigenetic changes linked to intergenerational inheritance of stunting

Question 23

Citations for growth disturbance factors in utero/at birth

Answer 23

• exposure to the mothers microbial community may cause complications in the growth of the foetus (Wells, 2017)
• vaginal delivery acts as a potential instance of contamination (biome seeding)- long-term effects on the offspring’s metabolism (Rautava et al, 2012)
• strong predictive link between metabolism and normal growth patterns in childhood (Nilsson et al, 2017)
• reduced space for foetus in women who themselves have stunted growth (Onis & Branca, 2016)

Question 24

Citations for dietary growth disturbance factors

Answer 24

• Mahfouz et al, 2022- malnutrition one of evading causes of stunting in children, Egypt- children who did not meet the recommended protein intake were over twice as likely to have stunted growth
• Braun et al, 2016- strong link between protein intake and growth trajectories in children between 1 and 9 years of age
• Tanner, 1992- growth is reflective of nutritional and hygienic status of a population

Question 25

Citations for social growth disturbance factors

Answer 25

- WHO- inadequate psychosocial stimulation can cause stunting - Bogin, 2020- stress hormones e.g. cortisol can lead to a hypermetabolic state of catobolism (the breaking down of body cells) as a stress response, which ultimately has a negative effect on bone growth - Worku et al, 2018- child-peer and child-mother interactions, as well as play time and materials, also has an influence on children’s developmental growth outcomes - Bass et al, 2016- these factors take effect through modulation of a child’s neurocognitive and motor development

Question 26

Citations for physical complications of childhood growth stunting

Answer 26

- Wells, 2017- early disruption to growth in infancy can influence body composition ratios across the lifespan, with potential to alter the ratio of lean tissue and body fat - Lee & Giovannucci, 2018- composition changes have later consequences for mortality risk - Onis & Branca, 2016- neural and cognitive abnormalities later in life e.g. abnormal postnatal development of apical dendrites from the cortex

Question 27

Citations for health-related complications of childhood growth stunting

Answer 27

- increased morbidity from infectious disease e.g. pneumonia (Black et al, 2008) and diarrhoea (Olefin et al, 2013) - non-communicable disease- increased cardiometabolic risks in adulthood (Rolfe et al, 2018), biomarkers for enteric dysfunction (Harper et al, 2018)

Question 28

Citations for socio-economic complications of childhood growth stunting

Answer 28

- 20% economic income decrease on average (Grantham-McGregor et al, 2007) - poorer school outcomes (Adair et al, 2013) - poorer peer and parent interaction (Brown & Pollitt, 1996)

Question 29

citations regarding extent to which consequences of childhood stunting are lifelong

Answer 29

-Wells, 2017- prolonged consequences of growth abnormalities are more likely if ecological stressors stunt growth during certain ‘critical windows’ - Soliman et al, 2021- developing brain is particularly vulnerable to nutrient insufficiency between 24 and 42 weeks of gestation - Hochberg, 2011- role of epigenetics- environmental challenges affecting growth may cause more profound and long-term consequences due to developmental plasticity

Question 30

adverse effects of catch up growth

Answer 30

- Sighal, 2017- several long-term adverse effects of early ‘catch-up’ growth itself, including risk of obesity and non-communicable disease

Question 31

Study example of culture as result of ecological necessity

Answer 31

- Grund (2019)- Sonso community of chimpanzees- individuals more likely to exhibit tool use in times of necessity - Ramsey (2007)- this behaviour spreads quickly in chimpanzee communities

Question 32

cited social learning definition (primates)

Answer 32

to learning influenced by observation of, or interaction with, anther individual or their products (Heyes, 1994)

Question 33

Influence of genetics on primate culture

Answer 33

Borell (2019)- behavioural differences in primates are greatly influenced by the genotype (genetic makeup of the individual)

Question 34

gene culture co-evolution theory with citations

Answer 34

- social learning causes cultural transmission of a certain behaviour - causes adaptive phenotypic variation - selection pressures to that population are changed, as the development of cultural practices modify the environment and thus impact the suitability of individuals to that environment (niche construction) (Laland, 2010) - This therefore has genetic consequences, as different functional genes within the population are selected - genetic changes cause a genetic evolution of cultural competencies, such as changes in brain size and structure- further effects cultural transmission - culture is developed through a bi-directional process; with cultural traits exerting a selection pressure on genetic traits and genetic traits influencing the transmission and evolution of cultural traits (Whitehead, 2019) - conclusions of this theory are still tentative, due to a lack of studies with directly comparable genetic and culture data for the organisms (Whitehead, 2019)

Question 35

Citations for sexual selection hypothesis of infanticide

Answer 35

- Hrdy et al, 1977- relative gain in genetic representation as killed offspring of male rivals - Pweiea, 1991- in seasonally breeding species e.g. ring-tailed lemur; male less likely to be chosen again in subsequent years if offspring killed by infanticide, as viewed as incompetent - Hrdy et al- evidence of genetic basis in rodents, interbirth intervals are indeed shorter, infanticide widespread

Question 36

Citations against sexual selection hypothesis of infanticide

Answer 36

- Sussman et al- only 12.5% of cases of infanticide meet requirements of sexual selection hypothesis (as infanticidal male rarely observed mating with mother (8/48), few involved direct attacks on independent infants (6/48) - Barlett, 1993- some infants got themselves into situation (e.g. by clinging to mother during conflict) could be due to characteristic that causes both e.g. overall aggression-infanticide just consequence of aggressive episodes- no genetic inheritance or direct selection for trait been provided

Question 37

Recent approach to possible selection of infanticide

Answer 37

- More recent DNA evidence- infanticide adaptive (Borries, 1999)- male attackers not related to victims, presumed killers subsequently fathers - Suggests is advantageous characteristic so could be produced by natural selection, but more evidence needed to assert whether by-product of aggression (genetic research is correlational), or whether independently selected (as most research in rodents)