ANTH 103

Name one primate for each taxonomic category, list where it lives, and state one interesting fact about it. Please number your answers to match the numbers here. (2 points each) 1. Strepsirrhine (wet-nosed primate) 2. Haplorhhine (dry-nosed primate) 3. Anthropoid (the tariser, monkeys, apes, and hominins are in this group) 4. Platyrrhines (New World Monkeys) 5. Catarrhines (Old World primates -- not just monkeys) 6. Apes 7. Hominins

1. Strepsirrhine (wet-nosed primate) - Aye-aye: Madagascar, is nocturnal 2. Haplorhhine (dry-nosed primate) - Barbary macaque: Atlas Mountains of Algeria and Morocco along with a small population of uncertain origin in Gibraltar, their cheeks hold as much food as their stomach 3. Anthropoid (the tariser, monkeys, apes, and hominins are in this group) - Chimpanzee: can be found discontinuously from southern Senegal across the forested belt north of the Congo River to western Uganda and western Tanzania, will wage war 4. Platyrrhines (New World Monkeys) - Spider monkey: South America, don't have thumbs 5. Catarrhines (Old World primates -- not just monkeys) - Macaque: native to northern India, Myanmar, can live in troops with as many as 100 6. Apes - Orangutan: rainforests of Borneo and Sumatra, can weigh up to 100kg 7. Hominins - Mountain gorilla: Virunga range of extinct volcanic mountains on the borders of the Democratic Republic of Congo (DRC), Rwanda and Uganda, and in the Bwindi Impenetrable National Park in Uganda, around only 1000 exist in the wild

LIST, in order (number these according to the list below) one skeletal characteristic that you would expect to find for each of these traits on a (1) left-handed, (2) short (3) male who was a (4) smoker with (5) syphilis and (6) cancer that has matastacized to the cranium. He (7) died at age 18. As a child, (8) his mother taught him to carry objects on his head (and heavy objects too, like buckets of water), which he continued do throughout his entire life. He (9) lost his top four incisors postmortem. In addition, early in life he broke his (10) left lower leg in a "tib-fib" football hit when he was 15. (Poor guy!)

1. The left arm bone would be slightly longer than the right arm. 2. measure the femur, take into account age and sex 3. Look at the pelvis. It should be narrower (unfit for child birth) 4. The bones should be denser since smoking reduced the blood flow through the body. 5. usually affects the humerus in a symmetrical diffuse involvement and leaves bone lesions 6. Metastasis cancer weakens the bones as well as in the skull you should see gray-black holes in the bone 7. After the age of 18 the wisdom teeth should be present fully 8. The weight strengthens your muscles such as the longus colli muscle, and that strength should be reflected in the neck bones. 9. The teeth should be missing with no sign of healing being shown 10. Look at the lower left leg, should show evidence of break but have healed completely.

The brain size of Homo erectus averaged about _____ cubic centimeters.

1000

How many thoracic vertebrae do you have?

12

When does M3 erupt, on average?

18

Homo erectus is unique among hominid species because it survived the longest, specifically, around _____ million years.

2

The earliest known and undisputed hominin tools from Gona, Ethiopia, date to _____ million years ago.

2.6 mya

How many bones (typically) are there in the human body?

206

Humans have approximately how many protein-coding genes?

25,000

What two bones are the arrows pointing to?

2nd medial and distal phalanges

How many chromosomes occur in a normal human somatic cell?

46

You are called in to a forensics case where all that has been found is a femur. You measure this bone using the osteometric board (it's 46 cm on the nose) and the following formula. What's your conclusion about this individual's height in terms of their height range? (Make sure you convert to inches from centimeters!) Use this formula (in cm): 2.47 x femur + 54.10 (± 3.72)

5'4" - 5'6"

According to the principle of independent assortment, there is a _____ percent chance that any tall pea plant will produce either yellow or green peas.

50

How many cervical vertebrae do giraffes, guenons, and early hominins have?

7

Of those whom have been massacred in Guatemala, which percent is indigenous Mayan?

83%

Who was Gregor Mendel?

A Monk who lived in what is now the Czech Republic.

Which stone tool industry is widely regarded as the invention of Homo erectus?

Acheulian

Homo erectus first evolved where?

Africa

All of the bones and any non-bony artifacts that are collected by, or brought to, the forensic anthropologist at one time for one case are called

An assemblage

Tuberculosis is an infectious disease caused by bacteria and it is spread through human contact. What does it look like on bones, and why are antibiotics not working on some strains of TB anymore?

As with any disease drug resistant strains start to occur. These strains that was resistant can be caught in two ways one being a person either is infected with a resistant strain, or during treatment, the bacteria mutate or pickup resistance genes from other organisms. TB usually causes joint pain

Tools were found at the same site as the fossils from which of the following?

Australopithecus garhi (means "surprise!")

This one should blow you away -- what do you notice about its face, and its canines? Huge huh? Hints: Has a tail! Hunts flamingoes! Lives in Africa!

Baboon

The study of human skeletal remains from archaeology sites is called

Bioarchaeology

Who put humans into the Animal Kingdom and the Primate Order?

Carolus Linnaeus

Name one comparison that you CANNOT use to try to determine sex in human skeletal remains.

Carpals and Tarsals orientation

Which scientist first proposed the idea that geological processes we see today are the same as those in the past?

Charles Lyell

Which group of people holds that the teachings of the Bible are infallible and that the scriptures are to be taken literally?

Christian fundamentalists

Forensic anthropologists estimate whether skeletal material may be male, female or intermediate by

Considering sexual dimorphism in human bony traits.

What term refers to the double-stranded molecule that contains the genetic code and is a main component of chromosomes?

DNA

Both biomedical anthropology and epidemiology focus on health and disease in different populations, but what is the difference between these two fields?

Epidemiologists focus more on statistics while biomedical anthropologists focus more on evolutionary aspects of health.

Who discovered Homo erectus in 1891/2 in Java?

Eugene DuBois

Describe what evolutionary medicine is and give one example where evolution played a role in finding out something crucial about a human health issue (it's ok if you use an example from earlier on in the exam).

Evolutionary medicine takes evolutionary history, culture, and environment into account when looking at health issues in humans. An example of this how people are trying to find a medicine that will beat drug resistant TB.

Name two ways forensic anthropologists determine age at death.

Examining tooth eruption and epiphyseal fusion

A dominant trait appears in its physical form only when two alleles for it are present.

False

A gathering and hunting diet typically consists of vegetables, fruits, wild game meat and fish, and dairy.

False

A hypothesis and a theory are the same thing.

False

Biological evolution is linear and directional.

False

Copernicus was the first to come up with the idea that the earth orbits the sun

False

Darwin knew of Mendel's work on inheritance, but chose to ignore it because it didn't make sense to him.

False

The blood pressure of living day gatherers and hunters is typically higher than 120/80, which is the "gold standard" for Americans.

False

You have one set of DNA and another set of chromosomes in each cellnucleus.

False

Apes have tails and monkeys do not.

False (but for some reason its true?)

Most of the human genome was formed during the agricultural revolution 10,000 years ago.

Flase

You have one set of DNA in the cell nucleus and also one separate set of chromosomes.

Flase

______ is an example of an ape.

Gibbon

Freddy Peccerelli's forensic anthropology and human rights work has taken place in which country?

Guatemala

______ is an example of a mokey.

Guenon

Some scientists have split Homo erectus into more than one species based mainly on geography. What do these researchers call Homo erectus fossils from Africa?

Homo ergaster

Probably the single most important advance in genetics has been the progress made by which project?

Human Genome

Why do female humans almost always practice "social births" (give birth with the help of others), while other primates don't?

Human babies have heads that are almost too large for the pelvic opening and they also have to twist front to back during delivery.

Gregor Mendel's major contribution to the study of inheritance was to show that:

Individual "particles" (genes), in various combinations, produce traits.

Which early scientist coined the term "biology" to refer to the study of living organisms?

Jean-Baptiste Lamarck

Who first recognized that species were groups of organisms that were distinguished from other such groups by their ability to mate with one another and produce fertile offspring?

John Ray

LCA stands for

Last Common Ancestor

What's the best way (most accurate) to estimate height in a human skeleton?

Measure the length of the femur

Which characteristics are influenced by alleles at only one genetic locus?

Medelian traits

MNI stands for

Minimum number of individuals

This is the only nocturnal monkey in the world. It's called the Douracouli or the Owl Monkey. Where does it live? (New World, Old World, Madagascar?)

New World

Which occurs regularly in gathering and hunting populations?

None of the things listed here occur regularly in gathering & hunting populations.

Measuring human skeletal remains with specific instruments such as an osteometric board is called`

Osteometry

What are the first two things you look for when you are trying to decide if a bone is from a human or from an animal?

Overall size and specific human adaptations

Which genus is potentially the earliest hominin for which we have evidence?

Sahelanthropus

What did Gregor Mendel find out during his lifetime of experimentation in plant hybridization?

That genes (he said "particles") come in pairs and are inherited as distinct units, one from each parent.

In her TED talk, Louise Leakey (daughter of the very famous Richard and Mary Leakey, who found and named Homo habilis, among other things), states which of the following:

That it's unusual that we're the only member of the Homo genus still alive and around today.

Which teeth are erupting in this photo?

The M3s

A skeletonized body is found in Humboldt County, and you are called in by the forensic anthropologist to assist on the case. The body has been disinterred (dug up) and brought to the Coroner's Office in Eureka, which has a fully stocked, working laboratory already set up. Describe the steps you would go through in the laboratory to conduct an investigation of the remains. Be specific and as detailed as possible.

The first thing to be done is to determine if the remains are human or non-human. After that the second step is determine if they are of recent or ancient Origins. Afterwards the skeletal analysis initially begins with the biological profile, which involves estimation of the deceased's sex, age of death, ancestry, and living height. You'd usually measure the femur for the height. To determine sex you can look at the features of the skull, as well as the features from the bones. Females usually have a smaller head, females also have wider pelvis' and these characteristics help to find out the sex of the individual. Once you have these you can narrow down the pool of missing persons to consider for comparison. A positive identification of an unknown individual can be made through comparisons of records taken during a person's lifetime these can include dental records, x-rays, etc. The last step is usually an analysis that involves a comprehensive assessment of the skeletal trauma, usually classified as blunt force, sharp force, or projectile trauma. Once you have figured out these things you can give a profile of the individual (if you haven't identified them yet) and a cause of death.

Who were the perpetrators of the massacres that have killed more than 200,000 civilian victims, many of whom were children and the elderly in Guatemala?

The police and military

What information can be gleaned from examining pubic symphyses (in particular the pubic symphyseal face)? Be as specific as you can, describing in general terms how different pubic symphyses look and what that might mean

The pubic symphyseal face is classified into six phases according to age-related features that are common in both males and females. The public symphyses is there to absorb the shock when walking. Also during childbirth it moves to accommodate the birth. Looking at this can show how old someone is or if they've given birth.

Who proposed that population size increases at a faster rate than food supplies?

Thomas Malthus

Which one of the following occurs through nondisjunction?

Trisomy 21

Apes have a larger cranial capacity than monkeys.

True

Bipedalism has contributed to the occurrence of complications during hominin pregnancy.

True

Bones "remodel" (have the capacity to build themselves back up), but teeth do not.

True

Energy derived from 'sugars' for hunters and gatherers is 1-2%, while it is at least 20-25% for Americans.

True

Evolutionary medicine takes evolutionary history, culture, and environment into account when looking at health issues in humans.

True

Genetic drift is the force of evolution that causes changes in allele frequencies, that are produced by random factors in isolated, small populations.

True

Humans are a generalized species.

True

Hunters and gatherers eat approximately ten times the amount of fiber than people living in America do.

True

In general, monkeys tend to be smaller than most of the apes.

True

The cell nucleus contains DNA and DNA is a main component of chromosomes that contains the genetic code.

True

The entry hole from a bullet is smaller than the exit hole.

True

When a person is heterozygous for hemoglobin alleles causing malformed hemoglobins, and they also have increased malaria resistance, they are carriers for the sickle cell trait.

True

When a small group of organisms leaves or becomes separated from their parent population and forms a new population in isolation it's called founder effect.

True

What's the main difference in the top causes of death in the U.S. between the year 1900 and the year 2000?

We went from dying mainly from infectious dieases to dying of lifestyle diseases.

A 52-year old male went missing in Thousand Oaks, CA and you get called not see if a skeleton that was found matches the description. You know what to do because you are a board certified forensic anthropologist. You first note a robust occipital protuberance, heavy nuchal and temporal lines, and big mastoid processes. The right femoral head is enormous, as is the humeral head. You note that the M3s had been extracted leaving smooth alveolar bone. Two of the ribs were broken and not healed, and the nasal bones showed sure signs of being broken earlier in life. Finally, you note that the sagittal suture is completely obliterated. Could it be true? Could this be a 52 year old male? Why? Provide a yes or no and a very short answer here, indicating which clues are irrelvant to determining if this skeleton was a 52-year-old male.

Yes it could be the missing 52-year old man. I know this because wisdom teeth are typically taken out in the late teens, and the removal of the M3s has left a smooth bone. Something that is also import is the fact that the sagittal suture is obliterated and that doesn't happen until age 30-40. One thing I don't believe is important in identifying the age is the fact that two of his ribs were broken and hadn't healed.

What bones hold your upper teeth?

Your maxillae

What new and exciting discovery, not yet even published in your textbook, was described in the "The skull of humanity's oldest known ancestor is changing our understanding of evolution" article?

a 3.8 myo cranium of Australopithecus anamensis that might be "Lucy's" ancestor

What the heck is a zygote?

a fertilized egg

What is a foramen?

a hole

What is an important feature in "robust" early hominins who probably ate a diet of tough vegetation, seeds and nuts?

a huge sagittal crest on the top of their heads where their temporalis chewing muscles attached

What is a hypothesis?

a provisional statement regarding certain scientific facts or observations.

Which condition in humans results in dwarfism due to growth defects involving the long bones of the arms and legs?

achondroplasia

From Ch. 5 Material: What is the term for the rapid expansion and diversification of groups of organisms into newly available ecological niches, like that we see in guenon monkeys, or Darwin's finches, or butterfly species?

adaptive radiation

Cranial suture closure is used by forensic anthropologists to help estimate/determine

age of death

If you have parasites when you are little, you are likely to NOT have this when you are older.

allergies

Move your arms around so that you can feel your scapulae (plural for scapula), those flat bones that are on your back. What are they sliding over when you move them?

almost all of your ribs

What's the type of bone called that holds the teeth? (Look at numbers 5&6 here, below.)

alveolar

An adaptation is _____.

an anatomical, physiological, or behavioral response to the environment. Next

Forensic anthropologists _____.

apply biological anthropological techniques to legal issues.

Dominant alleles

are expressed when paired with recessive alleles.

Oldowan tools

are the first known tools made by hominins.

Which bone is this?

axis

Who is this -- a nocturnal grub-eating lemur from Madagascar called the _____________- ____________? (notice the hyphen there -- you'll have to include it in your answer to get it correct)

aye-aye

Myopia, which doesn't occur in hunting and gathering populations, is

being near-sighted and in need of glasses or contacts to see objects that are far away.

The study of human biology within the framework of human evolution is primarily the domain of _____.

biological anthropologists

Humans have adapted to the natural environment through a series of long-term interactions between ____.

biology and culture.

This is NOT a chimpanzee. This type of primate only lives in Congo (DRC). What is it? Dr. G has studied it in the wild!

bonobo

What was the "black death?"

bubonic plague, caused by a bacterium trasmitted by rat fleas

What's your heel bone called?

calcaneus

Who is New World primate that you saw using tools and doing plant rubbing for parasites in the David Attenborough film?

capuchin monkey

Of the following listed, what types of cases do forensic anthropologists typically NOT work on?

cases that involve bodies that aren't skeletonized

The term evolution refers to _____.

changes in the genetic structure of a population from one generation to the next.

Look at those canines! And look at the size . . . this is no strepsirrhine (the wet-nosed lemurs and lorises) . . . this is not a monkey either! So can you guess which ape this is? Hint: Jane G. studies them . .

chimpanzee

What are the bones in red here?

clavicles

Our "tails" are which bone?

coccyx

The skull

consists of the cranium and the mandible.

What term refers to a suite of nonbiological adaptions to the environment, including learned behaviors that can be communicated to others, especially intergenerationally?

culture

What semifluid substance, found within the cell membrane, contains the nucleus and numerous other structures involved with cell function?

cytoplasm

What are the little orange bones here called?

distal phalanges

Dominant alleles are

expressed in the phenotype when paired with a recessive allele.

Humans now eat a lot more _______________ than we did during the paleolithic.

fat

What bone is this?

fibula

Your lateral "ankle bone" is actually which bone?

fibula

In the context of natural selection, what is a measure of the relative reproductive success of individuals?

fitness

The belief that species do not change, but are the same as when they were first created, is known as _____.

fixity

The soft spot on the top of a baby's head is called a

fontanelle

Which large whole in the bottom of the cranium in hominins allows the spinal column to connect to the brain and is a sure indicator of upright posture?

foramen magnum

Clyde Snow was a famous

forensic anthropologist.

What does Betty Pat Gatliff specialize in?

forensic facial reconstruction with clay

The initial step in the scientific method involves _____.

formulating a hypothesis.

From Ch. 5 Material: Taphonomy is the study of

fossilization

All the genes shared by the reproductive members of a population are called its _____.

gene pool

What's the evolutionary force that happens in small, isolated populations?

genetic drift

Darwin had little to no knowledge of which aspect of biology?

genetics

The entire genetic makeup of an individual is also known as its [________].

genome

This is the other kind of Asian ape. It is a ___________ .

gibbon

What do you think this primate is? Males, who can reach 400 pounds, are much larger than females, and these primates live in Africa. Koko is a famous one (in captivity), and Digit was a famous one from the wild.

gorilla

What are the two earliest two species in our genus Homo?

habilis and erectus

Humans are _____ bipeds.

habitual

Continuous or polygenic traits are things like

hitchhiker's thumb and hair color.

What the heck is this one!? It's crazy isn't it? Look at that jaw (mandible) -- tells you that it eats leaves and things that are harder to chew. This one has 3 premolars, meaning its from the New World (Central and/or South America). . . and it, yes, it make super loud vocalizations that can travel about a mile.

howler monkey

What shapes the "biocultural" viewpoint, used by biomedical anthropologists?

human evolution, biology, and culture

Why are humans getting taller since 1900?

improved nutrition and fewer infectious diseases

Where the heck is your vomer?

in your nasal cavity

Biomedical anthropologists assume that human growth

is a response that reflects adaptions to the environment.

"Ardi" (short for Ardipithecus)

is an early hominin who walked bipedally, in Ethiopia.

Human evolution _____.

is subject to the same forces that have acted upon other organisms.

According to the Smithsonian video, forensic anthropology

is the subfield of bioanth that helps solve murder and missing persons cases.

This little primate lives in Madagascar. The "dental comb" is something they use to groom one another and to scrape gum from trees. Its eyes are are a little more lateral than anthropoids' eyes are . . . so the question is, what type of primate lives on Madagascar?

lemur

In the Origin of Humans video (produced by HHMI Biointeractive), they talk about the traits that distinguish us from the nonhuman primates? Which of the following is NOT one of those traits?

long, curved fingers and toes for grasping tree branches

If you are a genetic carrier for sickle cell anemia, you have some immunity to which disease?

malaria

Bipeds have huge ____________________________ on their temporal bones where one of the major head stabilizing muscles attaches.

mastoid processes

Because we're bipedal hominins, we have large

mastoid processes.

Archaeologists study

material culture

How is the tibia oriented in relation to the fibula?

medially

Which term is used to describe small changes occurring within species, such as changes in allele frequencies?

microevolution

Which type of DNA is only inherited from the mother?

mitochondrial DNA (mtDNA)

Asexual cellular reproduction is also called

mitosis

What is the process of simple cell division by which somatic cells divide to produce two identical daughter cells?

mitosis

Which of the following does not increase genetic variation that is inherited?

mitosis

Which handsome guenon is this -- note that it has a white spot on either side of its tail?

mona monkey

Which term can refer to changes in DNA bases as well as changes in chromosome number and/or structure?

mutation

An alteration in genetic material occurring during meiosis where chromosomes "stick" together is called ___________________.

nondisjunction

If you're a cultural relativist you will

not judge cultures based on your own. Next

Adenine is one of the four

nucleotides

Which anthropologist focuses on the relationships between various dietary components, cultural practices, physiology, and certain aspects of health and disease?

nutritional anthropologists

What do most non-human animals NOT die of?

old age

What is the name of this ape from Asia?

orangutan

Which subdiscipline in biological anthropology examines anatomical and behavioral evolution as evidenced by the hominin fossil record?

paleoanthropology

What is the bone that is numbered 2 here?

parietal

Great chewers, like the robust australopithecines and gorillas, have sagittal crests that are ridges that have formed between which two cranial bones?

parietals

Where's the best place skeletally to look for sex differences?

pelvis

What term is used to refer to the observable, physical expression of a genotype?

phenotype

Mary Anning is credited with discovering the first complete skeleton fossil of which extinct creature?

plesiosaurus

Continuous traits, also called _____ traits, are influenced by genes at two or more loci.

polygenic

Scientists use _____ to produce many copies of small DNA fragments, such as those obtained at crime scenes or from fossils.

polymerase chain reaction

Which term refers to all or part of the skeleton, not including the skull, and literally means "behind the head"?

postcranial

Which tooth is missing in this dental formula? 2:1: ___:3

premolars

Which principle states that genes (alleles) occur in pairs because chromosomes occur in pairs and that, during gamete formation, the members of each pair of alleles separate, so that each gamete contains one member of each pair?

principle of segregation

Early hominins

probably scavenged and were prey themselves, more than they hunted other animals.

What bone is in your forearm, always on the thumb side?

radius

What is bone #10 here?

radius

What is the term used for a trait that is not expressed in heterozygotes?

recessive

What is the exchange of genetic material between paired chromosomes during meiosis, also known as "crossing over"?

recombination

Which types of genes act to control the expression of other genes?

regulatory

Name this bone:

scapula

What practice allows animal or plant breeders to choose which individuals will be mated based on the traits desired in the offspring?

selective breeding

What are the X and Y chromosomes called?

sex chromosomes

From Ch. 5 Material: Which term refers to the differences in physical characteristics between males and females of the same species?

sexual dimorphism

Alfred Russel Wallace

spent a total of 12 years in the field collecting and examining specimens.

Ok people! Check this thing out! This is one of the most interesting primates in terms of its taxomony (hint!), and also because of what it can do. It can leap 18 feet! And it's a "hunter" of small prey and large insects. Look at this tiny skull, with its huge eye sockets: Did you know that each of its eyes is bigger than its whole brain? What is your best guess of what this little primate's name is?

spider monkey

The average American eats 140 lbs. of this every year:

sugar

he femoral head is _________________ to the femoral condyles.

superior

Which key technological innovation related to stone tool manufacture is distinctive and has become synonymous with Homo erectus?

the "biface" or working both sides of a core

The term hominin refers to _________ .

the bipedal primates

What the heck is an epiphysis?

the end of a long bone

Which skull do you think is female?

the one on the left

Among the following, which is the best example of natural selection?

the recent increase in resistant strains of disease-causing microorganisms

Where do you look for age differences is you're using the "Suchey-Brooks Age Phases" chart?

the symphyseal face of the pubis bone

In scientific research, explanations of tested and robust relationships between natural phenomena are known as _____.

theories

What's the difference between the hand and foot phalanges?

they are much shorter in the feet

What were Darwin's and Wallace's two big problems?

they didn't know how traits were passed on or how variation was created.

The DNA base (or nucleotide) adenine always pairs with which other DNA base?

thymine

What is a great example of an evolutionary "mismatch?"

twinkies

What bone is this?

ulna

A relativistic view of culture allows us to _____.

understand other people's concerns and to view our own culture from a broader perspective.

Studying the behavior of nonhuman primates helps us _________________

understand the forces that shape modern humans and to understand the nonhuman primates themselves

Which theory proposes that characteristics acquired during the lifetime of an individual can be passed on to that individual's offspring?

use-disuse

Homo erectus individuals had a distinctive cranial shape. What is one of the more prominent features common to Homo erectus but not to Homo sapiens?

very large brow ridge

All hominins

walk bipedally.

Homo erectus is unique among hominid species because it _____________________ .

was probably the first hominin to harness and use fire.

Homo erectus is unique among hominid species because it ______________ .

was probably the first hominin to leave Africa.

The "Taung baby"

was the first hominin found in Africa and belongs to Australopithecus africanus

The Laetoli footprints

were most likely made by a member of the Australopithecus genus about 3.6 mya

From Ch. 5 Material: Mineralization happens

when something organic turns to rock.

Is forensic anthropology considered a subdiscipline of biological anthropology?

yes

We hominins have "interior tails." What is it called?

your coccyx

We know that with the advent of agriculture, cavities started to appear frequently in humans. What does cavity bacteria have to eat through to get to your tooth root?

your enamel and dentin

What do you sit on?

your ischium