Biology in the present: living people

Biology in the present: living people Chapter 5

Focus • Race…is it real? • Human variation and adaptation • Forensics

Is race biological? • Idea of race started in Renaissance when people began to travel widely and categorize things • Race means a taxonomic difference…i.e., different species with different genetics • Early scientists (Linnaeus and Blumenbach) used skin color as a determinant • Also said categories were fixed and unchanging

Is race biological? • Began with Linnaeus • 4 types of Homo sapiens: • H. sapiens Africanus negrus • H. sapiens Americanus rubescens • H. sapiens Asiaticus fucus • H. sapiens Europeus albescens • What is the criteria for each category?

Debunking race • Franz Boas (founder of American anthropology) challenged this concept of race • Especially idea of being unchanging • Because features varied so widely, race was invalid as a concept • Others found similar findings using blood type • Race is a folk taxonomy, or culturally created category with no biological basis

Quick assignment • For the following pictures, put the people into racial categories by ONLY LOOKING AT RACIAL FEATURES • Do not use geography, clothing, or any other CULTURAL features • They should fit into black, white, red, yellow, or other…we are using the skin color technique that has been historically used

Botswana Japan Australia Russia Brazil Norway India New Zealand

answers • Was it easy to put people into categories based just on skin color? • Is it easier to use ETHNIC descriptions like geography, language, and clothing?

Debunking race • Main findings: • 1. There is more variation within groups than between them • 2. With the extremely small amount of genetic differences in people, we are not different species and therefore cannot be different races

If not race, then what? • We us a clinal system instead of racial categories • This allows for all human variation in a spectrum • Human variation is continuously distributed around the world • One great example is the adaptation of skin color (we will discuss later)

Blood Type • Remember there are 4 blood types (phenotypes): • Type A, Type B, Type AB, Type O • With different genotypes: • AA or AO • BB or BO • AB • OO

Blood Type • Therefore, the O allele is the most common • It is the original allele and A and B are mutations • There are certain populations that have higher frequencies of certain blood types, but like race, it is a clinal system

adjustments • Adjustments are adaptations the humans have to survive in stressful environments, all to maintain homeostasis • Larger lung capacity for those in high altitude • Acclimatory are temporary biological adaptations • Sweating in heat or shivering in cold • Behavioral are cultural adaptations or behaviors to stressors • Build a fire or an igloo in cold environment • Go near water or fan yourself in hot environment

Which one?

Body shape • Body size and shape can also be adjustments • Bergmann’s Rule: animals in colder environments are short and stocky; those in hot ones are long and lean • Allen’s Rule:limb length has same principle: short in cold and long in hot environments

Skin color • Also an adjustment, depending on geography • Regulated by melanin (pigment)in the skin • Gloger’s Rule: animals near the equator will have darker skin and those far from equator will have lighter skin. • Why?

Light skin Vitamin D is important for bone health. Lack of this can cause the disease rickets. The vitamin needs radiation (sun) to by synthesized People who live in areas with less sun (away from Equator) have lighter skin to allow more synthesis This only explains light skin color

Dark skin For darker skin colors, people live near the Equator and have a similar relationship with folic acid, important in pregnancies Dark skin can be for protection against UV rays, for protecting skin from sun that can damage folic acid, and for camouflage

Skin Color • To summarize: • Vitamin D needs lots of UV  light skin • Folic Acid needs protection from UV  dark skin

Nutritional energy • Diet is vital to development • Humans have wide variety of food and are omnivorous, so we have adapted successfully to diet • Minimal energy needed to keep a person alive is basal metabolic requirement • Other energy is needed for growth, reproduction, exercise: total daily energy expenditure (TDEE) • Macronutrients (carbs, fats, proteins) • Micronutrients (vitamins and minerals)

Nutritional energy • Lack of these can cause serious developmental problems, health problems, and death • Undernourished: lack of calories • Malnourished: lack of balanced diet • 1 billion (1/7) of the world is currently starving • Partly due to decrease in variety from agriculture • Partly due to overpopulation

Genetics: Growth and Development Protein-caloric malnutrition: class of malnutrition that show growth problems. It includes: Kwashiorkor: (Ghanan) means “second child disease” because mostly happens once a child is weaned onto mainly starchy food. Growth is retarded, edema (water retention) happens in legs and feet, distended bellies, pshychomotor retardation

Genetics: Growth and Development Marasmus: results from diet low in protein and calories. Can happen any time, but also common at weaning. Extreme growth retardation, wasting of muscles, anemia and death.

overnutrition • In America, we have overnutrition, in which consuming too many calories, fats, and sugars leads to obesity and health problems • In U.S., more than 50% of population is overweight • Hypercholesterolemia: increases in cholesterol, which causes heart disease • Type II diabetes • What are other diseases we suffer from? Are they infectious or chronic?

Disease • Why are some diseases connected to “race” or ethnicity? • Sickle-cell? • Tay Sachs? • Cistic fibrosis? • These have a connection to a population’s genetics

Disease • But diabetes and high cholesterol are not “black diseases” • It is often the social atmosphere and economic inequality that leads to poor health in certain groups

The notion of race • What is eugenics? (p. 327) • How was this used to promote racism? • Why are we still using the concept of race if it is not valid?

The notion of race • What is eugenics? (p. 327) • How was this used to promote racism? • Why are we still using the concept of race if it is not valid? • It’s gone on for centuries • It is hard to change people’s minds, opinions, and culture • People think that because you can easily identify skin color, there has to be a biological basis for racial groups

Genetics: Growth and Development Every mammal has a set of deciduous teeth and permanent teeth These tend to form and erupt in normal patterns and can be used to identify age

Important Note: You can only use teeth to determine age up to 15 years because after age 16 we all have the same adult teeth for the rest of our lives • *** Use bone information first, and teeth secondary in determining age for forensics

Growth of bones • When born, bones are not fused together; there are spaces at growth centers called epiphyses • A person stops growing when these fuse together • Environment can influence growth • If malnutrition, disease, or other stressors, stature can be short • Americans have increased height steadily over decades

forensics • Used to identify age and sex of skeletal remains • Helps ID victims • In an adult skeleton: • By the 20s all growth plates have closed and all teeth are permanent • Remember, you can only use teeth up to age 15!

forensics • For sex, the skull and pelvis are most useful • Skull: • Males are larger, more muscular, square chin, prominent brow • Females are smaller, less robust, round chin, flat forehead • Pelvis: • Females have broader subpubic angle, wider sciatic notch and circular pelvic inlet • Males have narrow subpubic angle (less than 900), narrow sciatic notch, and triangle-shaped inlet • Look at pg. 310

For ASSINGMENT • Use the skeleton picture with epiphyseal closure (bone closure) ages • If the bone has not yet fused, the person is younger than that age • If the bone has fused, the person is at least that age, or older • Double-check ages with teeth ages (use bones first) • For sex, use the pelvic characteristics first and the skull second

Biology in the present: living people