Forensic Anthropology

WHAT IS FORENSIC ANTHROPOLOGY?

Is the study of the identification, analysis and interpretation of human skeletal remains from forensic contexts.

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Examination of human remains by forensic anthropologists focuses on three tasks :Identifying the victim or at least

providing a biological profile ( age, sex, stature, ancestry, anomalies, pathology and individual features)

Providing data regarding death event, including evidence of trauma

Reconstructing postmortem period based on condition of the remains and recovery context

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ESTIMATING AGE

Forensic physical anthropologist must be familiar with size of skeletons at all ages

Timing of formation, growth and fusion of diaphyses and epiphysis are patterned to create estimate

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DENTAL DEVELOPMENT Teeth can be a determinant of age or sex Tooth development differs by sex and

population

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SEXUAL DIMORPHISM

Male and female Homo Sapiens differ by size DNA methods can produce accurate

determinate of sex Genotype – genetic Phenotype- observed difference Determination of biological sex of skeletal

remains is an inexact science

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FRICTION RIDGES People can be identified by their fingerprints.

FRICTION RIDGES1. Friction ridges develop on the fetus in

their definitive form prior to birth. 2. Friction ridges are persistent

throughout life except for permanent scarring, disease or decomposition after death.

3. Friction ridge paths and the details in small areas of friction ridges are unique and never repeated.

4. Overall friction ridge patterns vary within limits which allow for classification.

DNA FORENSIC ANALYSIS

GENE FACTS

Human genome = 3.4 billion base pairs

Number of human genes: approx 100,000

Genes vary in length: average 3,000 bp

Only 5% of human genome is coding and contains genes

Genes divided into exons and introns Much of the function of the genome

unknown 0.1% difference in DNA between

individuals

The analysis of chromosomes is known as karyotyping.

DNA fingerprinting, also known as DNA profiling, is used in criminal and legal cases to

1. determine identity 2. determine parentage3. Identify the origin of a blood, semen,

or saliva in a sample.

STEPS OF DNA FINGERPRINTING

Extraction: DNA is extracted from cells or tissues of the body.

DNA – FORENSIC ANALYSIS

Collection of Evidence:Types of Unknown Samples: Blood,

Semen, Stains, Saliva, Hair follicles, Tissue, Bones, Teeth

Types of Known Samples: Blood / buccal swabs from suspect / victim / other known person.

**Avoid Contamination of DNA Evidence

Restriction Fragments: DNA is cut by restriction enzymes. Restriction enzymes recognize a unique pattern of DNA bases (restriction sites) and will cut the DNA at that specific location. Restriction fragments of varying lengths are formed when the DNA is cut.

Amplification: Specifically chosen DNA fragments are amplified using polymerase chain reaction.

Electrophoresis: DNA is loaded into the wells found in an agarose gel. When an electric current is passed through the gel, the negatively charged DNA fragments (pieces of DNA) migrate toward the positive end of the gel. DNA fragments are separated by size, with the smallest DNA fragments moving the fastest through the gel.

Transfer DNA to Nylon sheet by soaking them overnight.

Probing is done by adding radioactive or colored probes to nylon sheet to produce a pattern called DNA fingerprint.

DNA Fingerprint is built using several probes (5-10) probes simultaneously.

7 short, tandem (back to back) repeats of the nucleotide sequence AATG

AATG AATG AATG AATG AATG AATG AATG DNA molecule

DNA PROFILING USING STRS• STRs are Short Tandem Repeats of patterns of nucleotides

spread throughout our DNA• The number of repeats at a certain distinct region (locus,

plural=loci) of DNA is highly variable from person to person allowing their use in human identity testing

• The number of nucleotides involved in the repeats can vary between 9 and 80 (called variable number of repeats, VNTRs, or minisatellites) or between 2 and 5 (called microsatellites, SHORT tandem repeats, STRs)

• Several loci along our DNA have been identified as possessing STRs, and the DNA profiling community has selected 13 regions for identity analysis

• These 13 loci ALL contain 4 nucleotide (tetrameric) repeats

SHORT TANDEM REPEAT (STR)

It can start with a much smaller sample of DNA. STR analysis examines how often base pairs repeat in specific loci, or locations, on a DNA strand. These can be dinucleotide, trinucleotide, tetranucleotide or pentanucleotide repeats -- that is, repetitions of two, three, four or five base pairs. The likelihood that any two individuals (except identical twins) will have the same 13-loci DNA profile can be as high as 1 in 1 billion or greater.

EXAMPLE

http://evolution.berkeley.edu

Which of the following questions would not be asked of a family member of a victim of a mass disaster?

A What is the name of the victim\'s dentist?B Did the victim have any birthmarks, scars or

tattoos?C What was the victim\'s sexual orientation?D All of the above

Which of the following should be done at any outdoor forensic anthropological investigation?

A Avoid contaminationB Treat all findings as equally importantC Secure area

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