Exam 4 Bio Anth

Bioarchaeology

The study of skeletal remains from archaeological sites (10kya to historical) in order to determine the biological context of life and death from a cultural and archaeological perspective.

Forensic Anthropology:

The study of skeletal remains and other evidence in order to determine the causes and context of death with respect to legal and criminal matters.

Forensic anthropology differences from bioarchaeology

-contemporary sites

-attributes of individual

-legal/criminal matters

bioarchaology differences from forensic anthropology

-10kya to recent

-cultural attributes

-population attributes

similarities between forensic anthropology and bioarchaeology

Genetic information

•  Individual ID

•  Ancestry

•  Sex

Context of death

•  Premortem injury

•  Perimortem trauma

•  Postmortem context

Steps in Bioarchaeology/Forensic investigation

1. data from field site or crime scene

2. laboratory processing and curation

3. biological profile

4. taphono,y

5. identity and identification

What is the primary data source for bio archaeologists and forensic anthropologists

the field site/crime scene.

Sites can be found by accident, by surveys, or by systematic searching

 

Archaeological techniques are used to preserve the location and context of sites  

All possible contextual data is gathered and cataloged

 

All relevant data (e.g., artifacts, bones, criminal evidence …everything!) are sought after, collected, mapped, and recorded

 

Data are collected so that the entire site/crime scene can be reconstructed  

What are All artifacts, evidence, and/or skeletal material is brought back to for analysis?

the lab. These items are inventoried and analyzed

In forensic cases, the data constitute legal evidence and a chain of custody must be established

What do bioarchaeologists and forensic anthropologists begin to analyze the material to develop a biological profile of the skeletal remains?

biological profile

what information doe’s biological profile of the remains include?

-age

-sex

-ancestry

-injury/disease

As individuals grow, their (blank) change as well

their skeleton/teeth change

Researchers can study these changes to determine age at death (i.e., when growth stops)

lots of changes happen in (blank) , so identifying age at death is easier during this period

in juvenile years

fever changes happen from (blank) onward so identifying age at death is harder

adulthood

It is possible to calculate age from the eruption….

pattern of teeth

what can be used as an indicator of age in children from before birth to 10-12? (refer to “turkana boy”)

epiphyses (“bony ends”) to the shaft of the bone

female pelvis’s have…

-wide subpubic angle

-wide sciatic notch

-wide pubic bone

male pelvis’s have

-narrow subpubic angle

-narrow sciatic notch

-narrow pubic bone

women skulls have:

-more vertical forehead

-smaller mastoid process

men’s skulls have…

-larger brow ridge

-chin shape

-zygomatic arch extension

ancestry can include traits of…

of a particularly high frequency among populations (e.g., shovel-shaped incisors among some Asian populations), or culturally specific traits pertaining to particular groups.

In USA forensic anthropology it is possible to…

use a set of skeletal traits to statistically assign an individual to an ancestral geographic area, though this method has lots of error. It is also possible to assign an individual to an ancestral geographic area using genetic data.

Some traits that can distinguish ancestry:

incisor shape, palate shape, nasal spine, chin shape.

A combination of genetic markers can help determine an individual’s ancestry

what are indicators of nutritional stress and malnutrition among otherwise healthy individuals.

Adult teeth

When the enamel on teeth only partially develops, it forms an

enamel hypoplasia (usually lines or pits in the tooth enamel).)The enamel defect is proportional to the length of time that growth was impeded

Repetitive and/or asymmetrical activities and stress can

re-shape skeletal elements.  Bioarchaeologists and forensic anthropologists can study these patterns to infer activities.

Bioarchaeologists are particularly interested in distinguishing patterns of skeletal structures that occur

antemortem (before death) from postmortem (after death).

Wounds that occur at the time of death or soon-after…

don’t heal. For example, tooth loss during life leads to a different mandibular structure than tooth loss afterlife

It is important to distinguish if this skeleton was deliberately buried ( a ?? process) or from whether it represents a random death and assemblage of bones ( a ??process)

cultural and taphonomic

Taphonomy helps distinguish…

human intention from natural processes

most individual identification techniques rely on…

having some record and/or tissue samples of the individual while alive

The recovered insect species (and life cycle stage) can provide an indication of…

time since death

slower decomposition signs

Buried body

•Cold conditions

•Wrapped/Contained bodies

•Mass graves

Rapid decomposition

Surface deaths

•Summer/drier conditions

•Unwrapped bodies

•Single burials

An individual may be identified by

the pattern of tooth eruption, tooth position, and dental work.

what can compare dental x-rays taken from the individual while alive to those taken from the recovered individual?

radiographs

The frontal sinus has a

unique shape in humans.Provided that there are x-rays of the frontal sinus taken from an individual while alive, forensic anthropologists can compare antemortem and postmortem x-rays to identify individuals from the frontal sinus.

Using tissue samples it is possible to

compare genetic profile of a dead person to 1) their same genetic profile taken while alive; 2) the genetic profile of the individual’s relatives

examples of how forensic anthropology is used:

Mass fatalities

•Individual criminal cases

•War crimes/war dead

The environment can influence the expression of a trait. this modification can be…

permanent or it can be temporary

Direct model of a trait:

selection creates fixed adaptive traits in human populations based on environmental circumstances

adaptive phenotypic plasticity:

evolved genetic mechanisms to make short-term adjustments to our traits (= phenotypes) based on the environment.The ability to make beneficial physiological adjustments in phenotype in response to the environment.  Such changes are not inherited, but the capacity to make such changes is inherited and adaptive

Human populations can have (blank) for different environmental circumstances

adaptations.

e.g., darker skin in tropical populations

   (here the adaptation is skin color)

Human populations can also have (blank) responses to environmental circumstances

phenotypically plastic (=changeable and temporary)

e.g., the ability to tan when visiting tropical regions

   (here the adaptation is the capacity to respond)

Populations that have lived for a long time (evolved) in higher latitudes have adaptively…

evolved lighter skin.  Lighter skin is a fixed trait in this population.

But individuals from both populations also have the capacity to…

change their skin color over the short term (to tan) due to adaptive phenotypic plasticity.

Populations that have lived for a long time (evolve) in equatorial regions have..

adaptively evolved darker skin.  Darker skin is a fixed trait in this population

Examples of human phenotypic plasticity:

-tempurature adjustment

-altitude adjustment

-uv radiation adjustment

In all cases, there is an evolved ability for any individual to…

physiologically adjust to the external environment over the short-term.  But populations that have evolved over the long-term in these regions have evolved fixed traits that allow them to adapt to local conditions

vasodilation

expansion of blood vessels and increased blood flow to the skin (let’s blood flow to skin surface)

vasoconstriction

narrowing of blood vessels and reduced blood flow to the skin

long term adaptation In cold climates

large body size, shorter limbs. More internal mass, relative to skin surface (heat retention)

In hotter climates:

smaller body size, longer limbs

less internal mass, relative to skin surface

lack of oxygen in the body

hypoxia

oxygen is less concentrated at..

high altitudes

short term adaptation to cold climates:

body increases respiration and heart rate, and produces more red blood cells

Over the long-term:

Populations living in high altitudes have larger lungs, larger heart mass and slower rates of maturation

skin color is a visible source of …

phenotypic variation

Over the short-term:

human skin can change color based on exposure to sunlight (tanning)

Over the long-term:

a population’s average skin color reflects adaptations to protect it from UV radiation

what is the largest organ of the human body and the most visible aspect of our phenotype?

skin

how much skin do we have?

2 square meters of skin on average adult, and 2mm thick

two layers of skin

-dermis

-epidermis

Three substances which influence skin color:

•Hemoglobin

•Carotene

•Melanin

most important determinant of skin pigmentation:

melanin. more melanin =darker skin

Melanin is produced by

melanocytes

All humans have same number of…

melanocytes

Humans differ with respect to the amount and size of..

melanin produced

There is evidence that skin color is…

adaptive

Function of skin color:

protect body from harmful effects of UV radiation

UV radiation from sunlight penetrates skin and can damage DNA leading to…

skin cancer

 

Melanin absorbs UV radiation from sunlight, thereby…

protecting skin

UV radiation is most intense along

equatorial regions. In these regions, skin color is darkest

UV radiation will damage…

folate acid (a B vitamin).Folate acid is necessary for DNA synthesis, red blood cell formation, and spermatogenesis (in males).

Low folate acid can lead to

birth defects

UV radiation necessary for the body to..

manufacture vitamin D.

what does the body use to synthesize vitamin d?

cholesterol in the skin + UV radiation to synthesize vitamin D. Vitamin D important for bone growth and important during pregnancy and lactation

 

Lack of vitamin D can lead to

bone deformities (e.g., rickets)

 

Too much melanin can inhibit…

vitamin D synthesis, when UV radiation is relatively low

Darker skin protects against

skin cancer and folate acid destruction (both caused by UV radiation, which is intense along the equator)

lighter skin allows for

vitamin D synthesis in regions where UV radiation is less intense

Primitive skin color likely

light skin. Chimps have lighter skin under their hair, and darker skin in hairless regions (e.g., face).

Body hair protects the skin..

from UV radiation

why did we lose our body hair?

a “naked ape” would have fewer parasites

social creatures have higher probability of trsndmuting parasites to others (humans lived in large groups and are highly social)

humans can signal their parasite free bodies to others, a mate-attraction strategy

Naked skin is a better..

system of cooling the body, particularly in savannah environments—early hominins likely inhabited a savannah environment (which is sunnier than the forest).

Relative to chimpanzees, we have an

increased amount of sweat glands

 

Body hair stays wetter longer, thus slows evaporative cooling

No hair allows for more efficient

evaporative cooling

 

Standing upright:

less body surface exposed to sun rays

 

Higher wind-speed away from ground; cooler temperatures near head

Advantages to hairlessness

fewer parasites, better cooling

Disadvantages

more exposure to uv radiation

Melanin production regulates our ability to absorb

UV and synthesize vitamin D, which results in differences in skin color across geographic regions (due to differences in UV)