Forensic Anthropology Final

Biological Profile

What can we learn from bone morphology?

• Age

• Sex (not gender!!)

• Ancestral group (to an extent)

• Stature and body mass

Biomolecules

Biomolecules are “large organic compounds found in living organisms and sometimes present, usually in a partly degraded state, in the remains of those organisms after their death”

We are going to include stable isotopes in that definition

Multi-”omics”

• Genomics deals with DNA, which is found in all organic material and soils

  • RNA doesn’t last very long and doesn’t tell us much DNA can’t

• Proteomics deals with proteins, which are found in similar places to DNA, as DNA codes for them

• Metabolomics deals with lipids and carbohydrates, which are residues of fat, oils, resins and starches

• Isotopes are not biomolecules, perse, but are contained within the other biomolecule classes and their analysis is conducted with bulk protein or lipid preps

Biomolecules in Forensics

• Study biomolecules from teeth, bone, hair, and nails

• For forensic contexts, lipids, proteins, and carbohydrates are less commonly studied, while DNA and isotopes are more commonly studied

DNA is frequently used in forensic contexts

Cases solved with DNA

• Golden State Killer

• Boston Strangler

• Fawn Mari Cox Murder

• Susan Berman Murder

• 1975 Teree Becker Cold Case

First DNA case

Leicestershire England

• Victims:

  • November 21st 1983, 15-year-old Lynda Mann

  • July 31st 1986, 15-year-old Dawn Ashworth

• Semen recovered, only blood type able to be reconstructed

• False confession wrested from local 17-year-old boy with learning disabilities, Richard Buckland

• Eventually, Colin Pitchfork DNA matched to that of the semen sample

  • Pitchfork’s parole was reviewed and denied 2025

  • Point being – very recent technology

DNA

Exons: Protein coding portions of the DNA

Introns: Non-protein coding portions of the DNA

• Do all sorts of stuff you don’t need to know about

• Esp. gene regulation

Deoxyribonucleic acid

• In contrast to RNA – Ribonucleic acid

Stores biological data

• Chromosomal sex

• Ancestry

• Pathogens

• Biological relatedness (phylogenetics)

String of nucleotide bases (Adenine, Cytosine, Thymine, Guanine) = polynucleotide chain

Adenine always pairs with Thymine

Cytosine always pairs with Guanine

In coding DNA

• Every 3 base pairs forms a ‘codon’

• Codes for a specific amino acid

• Amino acids combine to form proteins

DNA - Chromosomes

• DNA found in chromosomes in the nucleus of each cell

• Each human cell nucleus has 23 pairs of chromosomes (one inherited from each parent)

  • 46 in total

• Segments of chromosomes that code for proteins are called genes

  • Alternative forms of the same gene are called alleles

DNA - Genome

• Complete set of genetic material is called a genome

• Not all portions of the genome code for proteins

• “There are approximately 1013 cells in the adult human body, and each one has its own copy or copies of the genome…”

22 sets are autosomes

1 set are sex chromosomes

• Males: XY

• Females: XX

XX and XY chromosomes are passed down differently

Females pass down genes located on each X chromosome to offspring. Each offspring has a unique combination of genes

• The two X chromosomes undergo recombination, exchanging material

• True of males and females

Males pass down their X chromosome without recombination because it lacks another X counterpart

Y chromosomes likewise do not undergo recombination, so they are passed down without change

DNA

• Single nucleotide polymorphisms (SNPs) are variants at a single nucleotide location

• Any time a polymorphism occurs, a new “branch” is created

• The SNPs are passed down, therefore frequencies vary by population

• Each offspring has a mixture of maternal and paternal SNPs → record of grandparent polymorphisms, etc. → ancestral group = haplogroups

• Groups of repeating DNA nucleotide bases are called short tandem repeats (STRs)

• Help establish a likelihood of genetic proximity (family relationships) based on shared # of repeats

DNA

Remember: each cell contains all 23 sets of chromosomes in its nucleus

1) Nuclear DNA→ a.k.a autosomal DNA. Found in cell nucleus of all chromosomes. Reflects the DNA of the 22 autosomes

Contains genes that code for physical appearance (phenotype)

2) Y chromosome DNA → found in cell nucleus. Useful for tracing paternal lineage

If females have 2 sets of X chromosomes in their cell nucleus, how could we differentiate between mother’s maternal lineage and father’s maternal lineage?

3) Mitochondrial DNA (mDNA)→ found in cell mitochondria on X chromosomes. Transferred between females via egg cells. No sperm involvement

Mitochondrial genome shorter and more copious than nuclear genome, more likely to survive in badly degraded cases

• mtDNA: thousands of copies per cell, nuclear DNA: two copies per cell

• mtDNA: 16,500 bases long, nuclear DNA: 3.2 billion bases long

• Why do mitochondria have their own DNA?: “Endosymbiosis”

DNA

• SNPs on Y chromosome DNA and mtDNA male and female lineages, respectively

• Fall into haplogroups (Haplo means “one”)

Map of global human genetic diversity

What samples studied for DNA?

Organic components found in skin, hair, blood, semen, and vaginal fluids

• Anything with cells!

Will discuss more about these types of evidence in a few weeks

How is DNA studied?

• In the past: Polymerase Chain Reaction (PCR)

• Amplifies extant endogenous DNA to allow for typing

• Cycle of heating and cooling essentially zip and unzip, allowing for sequences to copy

• Take finalized solution and put it into a…

• Agarose Gel Electrophoresis allows for visualization of PCR

• Principles of Gel Electrophoresis

  • DNA has a specific charge and length

  • Agar gel is electrified

  • Longer chains make it less far

• Doesn’t require sequencing entire genome

  • Allows for a focus on a few specific genes likely to be variable and preserved

• PCR was invented by Kary Mullis

• Probably one of the most important discoveries in the history of science

• “It's impossible to overstate PCR's impact. The ability to generate as much DNA of a specific sequence as you want, starting from a few simple chemicals and some temperature changes—it's just magical”

  • David Bilder

• Today: Next Gen Sequencing (NGS)

• Benefits = “Hypothesis-free” approach, higher discovery power; High throughput = less cumbersome for large samples or samples with many regions of interest

• Require calibration with libraries

  • Portions of genomes made of different lengths

  • Human genome project (completed in 2022)

• A common method is Illumina

Forensic Anthropologists often deal with fully skeletonized cases… then what?

Skeletal remains have organic component: collagen!

Traditionally: dense weight-bearing bone, though to preserve DNA (e.g., femur, tibia), as well as tooth dentin, cementum.

Now: Petrous portion of the temporal bone

NAGPRA - Native American Graves Protection and Repatriation Act

Federal Law

• Human remains, funerary objects, sacred objects and objects of cultural significance held by public entities to be repatriated

Two criteria:

• Native American

• Tribal affiliation

Kennewick Man

• Discovered in 1996 in Washington by two college students

• Police called, thought to be a forensics case as the skull did not ”look” Native American, but “Caucasoid”

• A prehistoric spear point embedded in the hip-bone cast doubt on it being a “forensic” case

• Radiocarbon dating (C14) confirmed that remains were > 9000 years old

Three groups vied for authority over the remains:

1) After learning the ancient nature, Army Corps of Engineers (in charge of the land where bones were found) claimed authority over them, forced all scientific study to end, and put into an evidence locked at the sheriff’s office pending review.

• County coroner protested saying he had legal jurisdiction

2) A coalition of Columbia River Basin tribes and bands claimed the skeleton under NAGPRA and demanded the bones back for reburial.

• “From our oral histories, we know that our people have been part of this land since the beginning of time. We do not believe that our people migrated here from another continent, as the scientists do.”

3) James Chatters enlisted his friend and colleague Doug Owsley (National Museum of Natural History), a well-respected forensic anthropologist who ran cases for the CIA, the FBI, the State Department and various police departments. They wanted to study the remains due to their rarity.

• Owsley argued that they should be able to study the remains, as the skeletal remains bore no evidence of relatedness to any existing tribes. The skeleton lacked physical features characteristic of Native Americans

• The Army Corps told the tribal coalitions that they would eventually receive the remains after a window of open investigation was closed

  • The remains had to be studied forensically in order to find tribal affiliation, otherwise NAGPRA was not applicable

• The Army Corps was about to repatriate remains when Chatters, Owsley and a small group of scientists sued the US government and various Army departments. Lawsuits lasted years

• Remains moved around, mysteriously portions of the femora were removed, FBI launched investigation. Portions later found in the county coroner’s office...

• Scientists won lawsuit in 2002 (7 years later), with courts agreeing remains could not be Native affiliated

• Scientists studied remains intensely, felt features were most consistent with modern Polynesians

• “…the tribes continue to believe that Kennewick Man is their ancestor. They want the remains back for reburial. The corps, which still controls the skeleton, denied Owsley’s request to conduct numerous tests, including a histological examination of thin, stained sections of bone to help fix Kennewick Man’s age. Chemical analyses on a lone tooth would enable the scientists to narrow the search for his homeland by identifying what he ate and drank as a child. A tooth would also be a good source of DNA. Biomolecular science is advancing so rapidly that within five to ten years it may be possible to know what diseases Kennewick Man suffered from and what caused his death.” (2014)

Kennewick Man = The Ancient One

• Five tribes involved in repatriation: Colville, Yakama, Nez Perce, Umatilla and Wanapum

• President Obama signed bill repatriating remains

• Reburied in 2017 in undisclosed locatio

Proteins

• Coded by DNA

• Provide structure (e.g., collagen, osteocalcin, hemoglobin) and function in a number of other capacities

  • Subunits are amino acids, which connected via peptide chains

• Robust and highly diagnostic

• Widely studied as proteomes = proteomics

• Forensic Proteomics studies proteins to identify body fluids and tissues = serology

  • Different fluids and tissues have differently expressed proteins

  • E.g.: Hemoglobin in blood

• Proteomes are sensitive to behavior and the environment

  • Saliva proteome is dynamic in response to smoking and daily fluctuations in the microbiome

    • Seminal and vaginal proteomes, sweat and vomit

• Can be used when DNA is too damaged for

  • Fingerprints → trace left on surface

  • Species identification → species-specific proteins

  • Sex estimation → sex specific proteins

  • Postmortem interval → degradation rate of proteins

Studied by mass spectrometry (MS)

Analytical machine that identifies molecules by observing the behavior of their ions in varying electromagnetic fields.

• This behavior depends on the varying mass-to-charge ratio (m/z) of the ions.

Sample is first ionized

Magnetic sector MS

• Samples pass through magnetic fields, those with more inertia (heavier) won’t bend as much as those with less inertia (lighter)

• Beam hits the detector at different locations, detecting the ions

Time of flight (TOF) MS

• Measures speed, rather than weight

• Magnetic pulse propels ions down and whichever hits the detector first is lighter

Mass spectra

• Output of a mass spec

• Compared to known sample

Proteomics can help with the biological profile

• You can estimate the ______________ of children with high precision, but you can’t estimate the _________________.

• Why?

Amelogenin peptide analysis (APS)

• If a single tooth is found and no collagen is preserved, we can still estimate sex.

• Amelogenin→ protein deriving from the formation of dental enamel (ameloblasts)

• Tooth crown is etched into powder, material dissolved, inserted into MS, read as spectra

• Distinct amelogenin proteins on the X and Y chromosomes (AMELX, AMELY), each has a different amino acid chain and peptides

  • Known as ‘protein isoforms’

• Applicable for any tooth (permanent, deciduous)

Paleo-proteomics

Pioneered by UC Davis researchers

• Dr. Jelmer Eerkens (one of my advisors

• Dr. Glendon Parker

Some evidence that other proteins may be recoverable

• Possible insight into…

  • Stress

  • Disease

  • Sex

Preserve in the enamel

• We don’t have the same taphonomic restrictions

• Main restriction: $$$$$

Stable Isotope Analysis

Main underlying principle: “You are what you eat”

• …and drink and breath…

• The food you eat partially becomes energy

• The food you eat partially becomes you

The physical composition of your body comes from metabolic processes

• Anabolism = building

• Catabolism = breaking down

This is very helpful for biological anthropologists

Important parts of the atom for this class

• Nucleus: Dense, positively charged center.

  • Proton: Positively charged subatomic particle

  • Neutron: Neutral subatomic particle

• Electrons: Negatively charged subatomic particles

  • ”Orbit” the nucleus

If you remove…

• Proton: Different element

• Electron: Different ion

• Neutron: Different isotope

Isotopes

Atoms of same element with same number of protons and electrons, but different number of neutrons

• Variability in atomic mass

Naturally occur in the environment

When an organism consumes (and metabolize) food and water, it incorporates the source’s elemental composition

• You are what you eat!

• The carbon atoms in your bones are from your food and the air

The heavy and light isotopes are separated in a chemical reaction process called fractionation.

• Prefers lighter isotopes over heaver ones

Stable isotopes

Stable isotopes are isotopes that do not undergo radioactive decay.

• Can be light or heavy based on atomic mass

Analyzed via mass spectrometry

Interpreted by the ratio of an element’s heavier form to its lighter form (e.g. 13C/12C)

• Reported using delta notation (δ), expressed in parts per thousand (or per mil) (‰).

Unstable isotopes

Carbon 14

• After death, it begins to decay

• Radiocarbon dating

Chemical reaction between sunlight, the atmosphere, photosynthesizing plants, and their consumers

• All elemental signatures come from our environment

Tissues Studied for isotopes

Any tissue in sufficient quantity

• Best characterized tissues are…

• Hair, nails, teeth, collagen

Collagen → bone → remodels throughout life

• Analyzed via bulk averages

Carbonate/Apatite (Ca10(PO4)6(OH)2) → teeth → develop in childhood

• Analyzed via incremental sampling

Timeline

• Hair: ~1 cm/month

  • 1-2 week lag between dietary intake and root composition

• Nails: ~1-4 mm/month

• Bones: ~7 year average

• Teeth: Window into childhood

Carbon Isotopes

• δ^13 C/^12 C

• Speaks to plant consumption (direct or indirect)

• Photosynthetic pathway of plants

  • C4 vs. C3

  • E.g. Corn (maize) = C4 | wheat = C3

• Baseline: Know local plants!

  • Challenging in

Nitrogen Isotopes

• δ^15 N/^14 N

• Measures the trophic effect of meat protein consumption

  • Also helps differentiate aquatic vs. terrestrial animal diet

  • Aquatic soil δ 15N is more positive than terrestrial soils

• Vegans would have a “herbivore” diet

Oxygen Isotopes

• δ^18O/^16O

• Measures consumption of meteoric waters, which vary across (and within) landscapes

• Rainwater, freshwater, differs across latitude, altitude and distance from the sea

• Fractionation in the water cycle (evaporation, condensation, precipitation) leaves the heavier isotope (18O) behind

Human behavior influences isotopes

• Mobility → changing Sr across teeth

• Manuring soil → increases N

• Cooking food → increases or decreases O, C, N

• Starvation → increases N

• Breastfeeding → increases N

Oxygen

• Water treatment and origins will be different by region

• Not a perfect mobility proxy, but can provide a helpful signal

Strontium Isotopes

• 87^Sr/86^Sr

• Reflect local geological signature

  • Variation in 87Sr depends on amount of decaying rubidium in rock during formation

  • Varies from 0.720 – 0.703 on land

• Plants uptake strontium into their tissues

• Consumers uptake plant strontium into their teeth

  • Strontium substitutes for Ca in hydroxyapatite

• Baselines: local fauna

• High alcohol consumption also inhibits muscle protein synthesis

• Moderate alcohol consumption does not inhibit muscle protein synthesis

• Breastfeeding children are apex carnivores→ highest d15N levels

• Isotopes in forensics: Bottom line

  • Provenance people

  • Identify behavior, consumption patterns

  • Challenging

Histology

The microscopic study of tissues

• Includes soft (skin, muscle, etc.) and hard tissues (bone, teeth)

• Forensic Histopathology → study of tissues or biopsies to determine pathology (illness) in living patients and decedents. Make diagnosis based on findings (e.g., is it cancer, what type, etc.)

Hard Tissues

Bones are recording structures, which means they “respond to changes of physiological condition of an organism by changing their morphological characteristics as they grow.” (Klevezal 1996, 1)

Teeth

• Tooth enamel forms from tip of cusps down to roots in layers known as perikymata.

• During stressful life events experienced when the enamel was forming, perikymata may become exaggerated. These cessations of enamel growth are called linear enamel hypoplasia (LEH).

Enamel Histology

• Similar periodic growth (and growth arrest) characterizes the histological structure of tooth enamel and dentin

• Study of incremental development of dental tissues => periodicity

• In enamel, Striae of Retzius develop at a periodicity of ~8-9 days in humans; Cross striations: daily

• What does this mean?: Daily (24 h) record of circadian rythym, stress events recorded

• Remember, teeth start developing in utero!

• The neonatal line (NNL) applies the same premise to the birth event--> more stressful the event, the more accentuated the line

• Also visible in bone

• By this premise, unborn children lack a NNL

• Children born via c-section experience less stress and have thinner NNLs

Cementochronology

Unlike enamel and dentin, cementum continues growing throughout the entirety of life

1 light + 1 dark band = 1 year

Count up band pairs, add to age at which tooth root forms

More precise than other aging methods for adults

During reproduction (gestation, lactation), elemental composition of bone changes

Takeaways: these methods are destructive

• Important to thoroughly document sample prior to destruction

• As well as consult families, NoK, or descendants before destroying

• Sometimes they are also costly, making them prohibitive to certain labs

• Balance between morphological and biomolecular methods to build biological profile

The Osteological Paradox

How can you tell if a person was “healthy” or “sick”?

Now, what if both individuals had the same form of the same disease…

The inverse logic of the aforementioned example is what is known as the Osteological Paradox, or selective mortality

Those who are sicker succumb faster to their illness and die before skeleton can remodel.

Those who are healthier can endure their illness, allowing time for the skeleton to remodel

Pathology

• The study of disease. From the Greek pathos (suffering)

• Ever-evolving, expanding understanding of how disease affects humans

• We only observe lesions (NOT the disease itself)

  • From skeletal remains, differential diagnosis is often as good as you can get

• Important to understand etiology

  • Number of causes result in the same outcome

• Example: “This individual exhibits lesions consistent with cribra orbitalia which are a nonspecific indicator of stress that can reflect either prolonged nutritional deficiency or anemia”

Types of “Diseases”

Vascular

Inflammatory (infectious)

Traumatic

Anomaly (congenital/non-metric)

Metabolic (anemias/gout, etc.)

Interaction (neuromechanical)

Neoplastic (tumors/cancer)

Vascular Disease

• Diseases involving blood and the vessels which carry it

• Reduced blood flow to the limbs

• General appearance is increased vascularity

Examples: Thalassemia, anemia

Inflammatory or Infectious Disease

• Contracted virus or bacteria

• Area inflames

  • Increased blood flow

  • Pooling of blood

• Infection festers

  • Microorganisms multiply

• Infection spreads

  • Can spread locally (within an organ, or adjacent space)

  • Can spread systemically (through the blood or lymph nodes

Inflammatory or Infectious Disease Example: Periostosis

• Extremely common, from a traumatic event or numerous illnesses

• Inflammation of the bone’s periosteum (outer layer of tissue)

• Results in wood-like, bubbled texture on outside of bone

Inflammatory or Infectious Disease Example: Dental abcesses & caries

Abscesses form when food particles get stuck between teeth and bacteria festers

Dental caries (=cavities) form from acid-producing bacteria

Inflammatory or Infectious Disease Example: Leprosy (Hansen’s Disease)

• Spread via air

• Symptoms include skin lesions and muscle weakness

• Loss of sensation in digits and eventual loss of the digits

• Destruction of nasal cartilage

Inflammatory or Infectious Disease Example: Tuberculosis (TB)

• Spread via air droplets

• Acute or chronic infection of soft or skeletal tissues by bacteria

• Affects the lungs (and by proxy, nearby bones)

• Can result in vertebral degradation (Pott’s disease)

Inflammatory or Infectious Disease Example: Venereal Syphilis

• Can be sexually transmitted or transmitted from mother to child (breastfeeding)

• Affects the soft tissue as skin ulcers, sores on genitalia, benign growths

• Mainly affects tibia (saber shin) and cranial vault (stellate scarring)