Specialized Headgear

Antlers and Horns

Public Demand

• The demand for antlers and horns of many different animals has fueled illegal hunting and trafficking – Rhino horns: used for dagger handles in the

middle east, ground into powder it is used to treat fevers in traditional Chinese medicine

– Elk antlers: Sold as an aphrodisiac (sometimes $200 per ounce)• Become a problem in America’s national parks

What does the forensic scientist need to know?

• Forensic scientists are often sent parts from police seizures– First must identify from which animal the

antler/horn came– Must be able to tell the season the antler was

taken• Ex: Federal law says antlers in velvet must be treated

w/ formaldehyde• Chemical tests can be run

Anatomy of Horns

• Horns are a permanent part of the animals skull and have 3 layers

• Both males and females have horns (female usually smaller

• Horns are not shed– Except American

Pronghorns, who shed the keratin sheath once a year

Anatomy of Horns• Inner layer: extends up from the skull as a bony core• Middle layer: called the sheath, it is a thin layer of

blood-vessel-rich tissue that supplies blood to the outer layer– The sheath continues to grow throughout the animal’s

life• Outer layer: called the keratin layer, it is the “horn”

as we know it– Keratin is a protein that is also found in fingernails and

hair

Anatomy of Antlers

• Antlers grow from the skull and are shed once each year

• Made of bone that grows from two disc shaped bumps on the skull (Pedicles)

Anatomy of Antlers

• During the months when the antler is growing, the soft cartilage is covered by blood-vessel-rich skin called velvet– When the antler is finished growing, this tissue

dies, the cartilage hardens to bone, and the velvet falls off

• In all but one species (Caribou), only males grow antlers

How big do antlers and horns grow?• The size of a male’s antlers or horns tell a story– To grow large antlers, a male must be well fed and

healthy– Has to carry the weight

• Elk antlers can weigh up to 25-40 lbs.• Bighorn sheep horns can weigh as much as 30 lbs.

• So what’s the purpose?– Rutting (mating) season is the one time males gather

with female herds– Males battle with their headgear for territory and

mates

Antlers Through the Seasons

Spring to Mid-Summer

• Spring signals the start of new antlers• Soft layers of cartilage grow from pedicles• Grow very rapidly– Ex: moose antlers can grow 1 inch per day

• But why?– An increase in daylight triggers the body to make

high levels of the male hormone testosterone– This hormone stimulates antler growth

Late Summer

• Antlers begin to harden into bone• Velvet begins to fall off– Males can be seen rubbing their antlers on trees

to shed the velvet• But why?– Blood stops flowing through the velvet, causing

the living tissue to die

Early Fall

• Antlers are cleaned of all velvet– Marked with grooves and ridges where the blood

vessels used to be• Remain firmly attached to the skull• This is the season of rut (mating)– Use their antlers to battle for territory closest to

females• But why?– Testosterone remains high– Keeps antlers in place, but also affects behavior

Late Fall to Winter• Rut and mating season ends• Males go off on their own• Antlers fall off– Males can be seen rubbing partly attached antlers

on trees to help things along– Can lose one antler at a time

• But why?– Testosterone levels drop dramatically– Antler is no longer held to pedicle