ANTH 369 1/24/17 Today: ∙ Basic principles of growth and methods for assessing growth and maturity o Methods for assessing growth and maturity o Growth standards and references o Human variation in development o Poor growth and catch-up growth Assessment of maturation ∙ Dental markers of maturation o Formation and eruption of deciduous and permanent dentition Includes baby teeth and adult teeth Largely genetically and individually determined NOT influenced by environment and population Discussion: How do we assess the maturation of age? How do we get at interpreting this? ∙ Enamel samples to look at the makeup ∙ Look at the permanent molars: it is fully grown ∙ Emergence of secondary sexual characteristics o Changes of hormones and growth in the adolescent stages
Males ∙ Testes enlargement and sperm production ∙ Pubic hair ∙ Penis enlargement ∙ Axillary hair ∙ Facial hair
Why do we use PHV instead of age?
How do we get at interpreting this?
Discussion: How do we assess the maturation of age?
Females: ∙ Breast development ∙ Pubic hair ∙ Hip broadening ∙ Menstruation ∙ Fat deposition ∙ Fully “fecund” cycles
Don't forget about the age old question of -That is, what makes a thing good (morally right)?
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We also discuss several other topics like umd sociology
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We also discuss several other topics like amalgamize
Don't forget about the age old question of mgmt 200 purdue
Tanner Puberty stage classification system ∙ Classification into discrete stages of development of secondary sexual characteristics o Assessed in clinical setting or by self-assessment (due to privacy reasons) o Most researchers use the Tanner Scale (1-5 categories) o Breast development, genital development, pubic hair development ∙ Females o Earlier: Breast development, Pubic hairo Later Menstruation Ovulation ∙ Males o Earlier: Testosterone Pubic hair o Middle Sperm o Later Muscle growth Discussions: Why do we use PHV instead of age? ∙ Early and late mature processes ∙ Girls mature earlier than boys so it makes more sense What are the key sex differences? ∙ Distinct differences ∙ Ability to reproduce for females is after the peak in HV, men it’s before peak HV ∙ Sperm quality decreases slowly over time, women’s eggs stop quickly ∙ Women’s estrogen is variant on environment: o Long distance runners have decreased estrogen based on how much they run Growth Standards Back to our earlier example ∙ De Montbeillard’s son ∙ Final height over 6ft o tall for a French man in 18th century ∙ Questions: o How do we know that someone is “tall” or “short” o Environment differences? (he was wealthy) Growth reference charts ∙ To assess whether growth is “normal” or “typical” ∙ Depicts avg. height to be expected through growing years ∙ Depicts centiles (range of normal height in a percentile) o Point on the distribution ∙ Conditional upon sex and age o Can also add parental size but rarely done just for comparison and interpretation reasons Shared genetics and shared environment Target ranges∙ Median centile is 50% above, 50% below ∙ US model: 7 centiles (3,10,25, 50th, 75th, 90th, 97th) ∙ Reference curves may use mean and standard deviations if normal distribution o How many standard deviations are they above or below the mean? ∙ Z-score: indicates how many standard deviations a value is above or below the mean Growth charts based on a reference population ∙ Reference data must be based on an appropriate population standard ∙ How is it being used: clinical or public heath tool? o Misinterpretation matters ∙ Clinical: Child’s measurement centiles a measure of heath o Medical assessment as interpretation of centiles o Reference population must be appropriate o If small, default answer is there’s a problem with environment Have to prove it’s not the case ∙ Public Heath: Applicability to ind child less important o Goal: sum nutritional/growth status of a group of children in order to compare with other groups o Applies to different groups in different societies o Low and middle income nations often us WHO (international)/NCHS (US standards)/CDC charts Are we creating a problem by comparing a distinct population to US population? o Most developed nations use nationally specific charts US gives a renewal every few years (Fell’s longitudinal study) ∙ Growth standards vs. references o Standards: “optimal” situation, growing optimally without environmental discretions Much harder to carry out in reality, (exclude minorities? Medical conditions?) How do we do this ethically? Discussion: What are we motivated to carry out standards in populations? ∙ Contrast to wealthy societies to other minorities ∙ Creating standards to better different societies ∙ Further explore factors of growth ∙ Different people coming together to help interpret the public health standards ∙ What creates poor growth in terms of economics, nutrition, etc.? Developmental Age ∙ Differences in tempo of growth make problematic the notion of, for example, an “average” 14-year-old boyo Some 14 y-o pre-pubescent while others have finished their growth spurt and are sexually mature o Enormous differences may exist in sexual, emotional, and physical development in children Human Variation in Development ∙ Chronological age vs. Maturational age ∙ Same chronological age, but dramatic differences in maturity o Size o Appearance of secondary sexual characteristics o (some are early developers, others are late) ∙ Maturation assessed by markers, many of which are continuous in their change but divided into discrete stages o Ex: pubic hair development Canalization ∙ During childhood, all were growing near 50th centile ∙ After deviation because of AGS, they return to same centile position ∙ Very different formations on the HGV ∙ Adherence to particular centile or “canal” o Genetically determined o Target seeking “unconstrained environment” o Keep in this 50 centile canal Catch-Up growth ∙ But, no such thing as “unconstrained” environment ∙ Catch-up depends on timing, severity, and duration of insult ∙ Ex: Celiac syndrome and then diagnosis (can’t get adequate nutrients they need) o Growth was stunted (until age 11), then there was a change in environment (dietary) o Complete catch-up ∙ Note: this can be rare because this was in a wealthy environment. In poorer countries, you can’t get that same nutrients, thus no catch-up growth o Ex: In 3rd world countries, the children start growing well (breastfeeding), then after they fall short quickly Describing poor growth o When you look at 2 measures of poor growth o Stunting: Assessed by height for age o Long-term nutrition o Wasting: assessed by weight for height o This is present/near past nutritional statusANTH 369 1/26/17 Today: ∙ Evolutionary and comparative perspectives on human growth o Life history approaches o Mammalian and primate foundations of human growth o Brain evolution and the human life history pattern o Integration of evolutionary and biocultural perspectives Discussion: Points of interest in the last week: ∙ Importance of repeatable, objective, analysis (even for straightforward measurements) o Need to standardize ∙ Issue of cost vs. convenience (BMI is easy and cheap and is easily transferred over populations, whereas high resolution measurements are much more expensive. There is a time and place for everything ∙ Importance of visceral adipose tissue, focus on different types of body fat ∙ Difference types of maturation markers, may focus on one or another ∙ Genetic patterns of growth, but also influence on the environment ∙ Sex difference in adolescence in terms of rate of growth ∙ Use of reference populations and growth o Reality: Comparing populations is incredibly complicated The human life cycle is unique ∙ Life history traits in humans o Short duration of breast feeding o Short interbirth interval o Delayed development (prolonged childhood) o Pronounced growth spurt An evolutionary life history perspective ∙ Describing the human pattern vs. other close related species o Then focus on the HOW then the WHY ∙ Variety of factors shape growth and development o Genetics o Environmental influences o Note: It’s never nature or nurture, always both, just how much of each) ∙ A life history perspective (branch of evolutionary theory, a way to understand changes) o Patterns of growth and development can be viewed as adaptations o Any point in life course can be the focus of evolutionary change o What has to happen in terms of growth and development that leads you to grow in a certain way? Mammalian life histories∙ Life History: Theoretical framework that focuses on the strategies an organism uses to allocate energy (calories) and other resources to: o Basic survival costs (maintenance, thermoregulation, activity, etc.) and productive costs (growth and reproduction) Less energy for survival, more into productive o Focuses on: Timing of key life events (birth~ how long the baby stays in the mother, weaning, age at reproductive maturation, longevity~ how long species lives) Trade-off allocation: resources (energy) are generally limited; investment in one function affects investment in others ∙ Appropriate trade-offs dictated by environment Something Old, Something New ∙ Focus: conserved traits (traits are kept in history), and derived traits (the newer traits that develop) o Separate the new traits vs the old traits o Decide the importance of the new emerging traits o Discussion Questions: How do we know whether a trait is derived or whether it is a conserved trait? ∙ Conserved: what do we have in common with living species (ex: thumbs) ∙ Derived: Nothing like other living species (ex: standing upright) Did we evolve from chimpanzees? ∙ No: We have a common ancestor, but not based off chimpanzees themselves o Look close to the common ancestor, they look like chimpanzees than us o New question: how did we Mammalian and Primate Foundations of Human Growth Humans as mammals and primates ∙ Many human morphological, physiological, and behavioral features rooted in mammalian patterns ∙ Features of mammals relevant to life history: o Features live lives that are expensive in terms of energy expenditure and consumption o Mammals can inhabit many different environments o Mammals live flexible lives both in terms of behavior and biology Our heritage as mammals∙ High energy costs of endothermy but allows environmental diversity o We do things differently in terms of regulating temperature and energy ∙ Increased relative brain size (same as dolphins, elephants) o Greatly enlarged cerebrum (Neocortex with higher-order thinking) for processing sensory information High, obligate metabolic demands Increased behavioral flexibility and learning ∙ Dietary adaptations o Helps meet relatively high and continuous energy demands Ex: Heterodont dentition (different teeth variations to optimize use) Beaver: continuously growing incisors are useful for food and trees Humans: a well-adapted omnivore (not specialized to eat one or 2 things) ∙ Locomotor adaptations o More dependent on an active life o Growth phase then reproductive phase o Set adult size: finite period of bone growth (epiphyseal fusion) ∙ Unique reproductive biology o High reproductive costs Placenta: efficient maternal nourishment Lactation: High quality nutrition to poorly developed, toothless infant o Mother remains mobile during gestation and buffers from external environment Different than fish (who dump eggs in a stream) Here, investment in smaller number of offspring o Increased mother-infant interaction after birth Importance of bonding with mother and offspring o Divergence in male and female (anatomy, physiology, and behavior) Sexual dimorphism: two different shapes/size for the sexes (size, antlers, etc.) ∙ Emphasis on Body fat o Fat reserves allow for energy buffering Fat present in other vertebrates but most for mammals ∙ Ex: Bears in the winter, whales, etc. Nutritional reserves especially important in reproduction and growth o Human body fat primarily as energy buffer but amount and distribution has reproductive role ∙ Emphasis on sociality and parental care o In general, mammals lead “slower” lives (more “K” selected, or well adapted for environments where it takes investment to grow offspring) Contrast: R-selected: many offspring, not much attention Emphasis on quality over quantity but considerable variation o Increased dependency Importance of mother-infant bond Increased opportunities for infant learning and behavioral flexibility Optimal growth includes a stimulating environment (social involving) o Increased reliance on behavioral flexibility and learned information Discussion: Why are some species more K-selected and other are more r-selected? ∙ Environment: social dimensions and what is invested o Why sociality in first place? Cooperative aspect, teamwork, etc. ∙ R-selected: well in unpredictable environment (more genetic variation), it’s going to help some offspring adapt ∙ Increased biological and behavioral flexibility o Relatively long lifespan and increased physiological, behavioral, and morphological flexibility Environmental tracking Developmental plasticity ∙ Greater effects of proximate environment on phenotype ∙ Ex: baboons o Baboons foraging in an East African garbage dump o Sexual maturity earlier in food enhanced o Sexual dimorphism enhanced