Friday, July 18, 2014

Bodies in Motion

This month I resigned from my job. Not because it’s a bad job; I resigned based on a visceral feeling that it’s time to move on. It’s not the first time I’ve walked away from my life. After thirteen years as a firefighter-paramedic, I experienced the same sense of restlessness, that consuming need for a new direction. So I’ve cleaned out my office, sold my house, and will now venture forth into the unknown.

Fortunately, I’m not without means. I have my fire department pension and a nice little nest egg put aside. A life-threatening allergy to small children has enabled me to skirt parenthood, so I’m in pretty good shape financially. Therefore, I’m chucking this life to do a bit of wandering and see what pops up on the horizon.

Moving is always a pain. I’m determined to scale back my life and rid myself of unnecessary baggage; stuff I’ve accumulated over the years that has lain dormant and untouched. I’ve even started parceling off my library, the ultimate sacrifice for any self-respecting nerd.

My impending move got me thinking about movement in general. So in an effort to divert my thoughts from packing, I want to discuss the amazing ways our bodies move us through life.

Imagine reaching for a cup of coffee (or in my case, a glass of gin), taking a bite of a sandwich, or brushing your teeth. These actions – reaching, lifting, connecting and returning – are accomplished with barely a thought. We take for granted that our bones and muscles will work in concert to achieve the desired action, which is all the more apparent when we suffer an injury that limits movement.

The 206 bones in your body and the 600-plus muscles on your frame (known collectively as the musculoskeletal system) cooperate to move your body through space. Since contracting muscles can only pull on the skeleton, there must be opposing muscles that reverse the action. For example, when you bend your arm to take a bite of that sandwich, your biceps flex while your triceps relax. When you straighten your arm to put the sandwich down, they reverse roles. This “working together” is referred to as antagonistic action and it occurs throughout the moveable parts of your body.

There are various types of body movement. Flexion is just as it sounds: bending at a joint, as when you bring your foot up to the back of your thigh. Extension is the opposite – a straightening of the joint – as you return your foot to the ground. The movement of your limbs away from your body is known as abduction (as when you reach to hang something up); adduction involves moving them towards your midline. And finally, circumduction is the movement of a limb around a joint, as when you swing your arm in a wide circle.

But these intentional movements don’t just happen, even though many of them seem automatic. Movement originates in the central nervous system, cromprised of the brain and spinal cord, where lightning-fast impulses race along motor neurons. These impulses cause your body to react via the peripheral nervous system, which includes your arms, hands, legs and feet. Sensory nerves deliver information back to your brain and it’s this beautiful synchronization between motor and sensation that enables movement. Think about it… every single movement you make, from the smallest (batting your eyes) to the grandest (jumping a puddle) is carried out through the communication between brain, nerves, bones, and muscles. It’s truly mind-boggling.

But what about unconscious movement? Even if we sit perfectly still, parts of our bodies are still moving, acting on directives from the brain that never register consciously. And, thank goodness. Imagine if you had to direct your heart to beat, your lungs to expand, your bowels to digest, eyes to blink, or your throat to swallow. You probably wouldn’t get a whole lot done. That’s the beauty of the autonomic nervous system – that complex arrangement of nerves that connects the central nervous system to the heart, lungs, and many of your internal organs. It works reflexively and involuntarily, maintaining a steady state (homeostasis) within the body, controlling heart rate, breathing, and circulation, along with all the other bodily functions that keep us alive.

The body’s movements are wondrous to behold. They keep us alive, physiologically and emotionally. As we run or dance or embrace, our hearts are beating, our blood is coursing, and our breath is rushing in. Imagine your life without movement. Think about those who lose their ability through accident or disease; those stoic individuals who live on in the face of paralysis. They are truly the face of courage.

So as you move through your day, think about this wonderful gift and take none of it for granted. Movement propels us forward, and is graciously complemented by the leaps and bounds of our minds.

I leave you with this quote from philosopher Allan Bloom:

See you next Friday.

Friday, July 11, 2014

The Body as Evidence


 Although all humans are of the same species, with the same overall body parts, there are a number of attributes that are specific to each individual, even in the case of identical twins. These specifics come in handy when it comes to solving crimes.

During grad school, I had the good fortune of completing a Directed Independent Study at the C.A. Pound Human Identification Lab, located on the outskirts of the University of Florida campus. I trained under the assistant director, Dr. Michael Warren, who would go on to play a leading forensic role in the infamous Casey Anthony trial. The training was meant to supplement my studies in bioarchaeology, for both forensic anthropology and bioarchaeology utilize many of the same techniques. Both specialties rely on the examination of the skeleton; however, bioarchaeology deals with ancient remains while forensics focuses on contemporary deaths – typically those occurring within the past fifty years.

Working at the Pound Lab was a great experience. Each day, Michael would pull a box from the back shelves where the old cases reside and I would set to work on the remains, placing the bones in anatomical order, determining the age, sex, and height of the person, and noting any pathologies and unique identifiers, such as dental work or skeletal anomalies. From X-raying decapitated heads to defleshing a young girl, my work at the lab provided an up-close-and-personal glimpse of forensic science (along with a few cases of the dry heaves).

So I thought we would explore how our bodies serve as evidence – not as victims, but as perpetrators. Let’s examine the clues our bodies leave behind.

Say you commit a heinous crime, one that includes the deadly duo of rape and murder. There are myriad ways you can be linked to that crime. Let’s start with the tried-and-true method, fingerprints.

No two people share the same fingerprint. Even identical twins, who have the same DNA, will have differences in their fingerprints, since the “friction ridge skin,” as it is known in professional circles, is a result of many environmental factors, such as bone growth and conditions within the womb. And although Sir William James Herschel is credited with being the first to use fingerprints as a means of identification back in 1858, it seems the Chinese were about two thousand years ahead of the curve.

In “The Volume of Crime Scene Investigation - Burglary,” dated to around 200 B.C., the Chinese mention the use of handprints as evidence. They were also using fingerprints on clay seals to secure documents, which is pretty clever, considering they wouldn’t invent paper for another three hundred years.

It wasn’t until 1892 that fingerprints were first used to solve a homicide. That accomplishment goes to Argentina, whose Buenos Aires sleuths relied on prints to solve the Rojas murder case in which the mother of two brutally slain boys eventually confessed after her bloody fingerprint was identified at the crime scene.

But fingerprints are just the start of the biological trail. Let’s talk semen.

There are usually about two hundred million sperm swimming within a single ejaculate, making it the perfect fluid for DNA analysis. Even individuals who can’t produce sperm (aspermiacs) and those who have been clipped (vasectomized) can still be identified based on their seminal fluid. The test for semen at a crime scene is cheerfully known as “The Christmas Tree Stain,” since the reagents stain the sperm in blues, greens, and reds. Once the sperm are recovered, the DNA packed within each little swimmer can be matched to a culprit.

But semen is just one of several bodily fluids used in identification. Blood is another popular means of narrowing down, or eliminating, suspects. By identifying the grouping (A, B, O, or AB), the presence of Rhesus antigens (Rh factor), and certain genes, investigators are able to match or disqualify an individual based on their results.

Saliva is another common fluid recovered at crime scenes. It can be found on the victim, as can bite marks, or left on objects such as cigarette butts, glasse,s or cans of soda, and is another valuable source of DNA. But bodily fluids, which fall under the specialty of “forensic serology,” also include anything excreted or secreted from the body, including urine, vomit, oils from the skin, and feces.

And let’s not forget about hair. The human body sports around five million hair follicles. On average, we lose around one hundred hairs per day. The length and quality of the hair is based on the region of the body from which it sprouts and ancestry dictates whether it is light, dark, straight, or kinky. Microscopic characteristics of hair enable investigators to differentiate between individuals and to determine whether the hair has been chemically altered, thus providing another link between suspect and crime scene.

Whether it’s semen, blood, spit, or hair, our bodies, as living organisms, leave behind a biological trail. And as the science of forensics becomes more exact, that trail becomes easier to follow.

Something to think about the next time murder crosses your mind…

Here's the Smithsonian's excellent interactive website on forensic anthropology.
Enjoy and I'll see you next week!

Friday, July 4, 2014

Tales from the Poo...

They say big things come in small packages. This is certainly the case with archaeology. We can take the smallest bit of evidence – a fragment of bone, a shard of pottery – and extract a wealth of information from the pieces of human history buried within the archaeological record. And one of these small parcels of the past offers an array of cultural, biological and environmental information. I’m referring to ancient poo.

Since we’ve already explored the myriad ways humans emit odor (last week’s Why We Stink!), I felt it only natural to highlight one of our smellier byproducts, feces. And from the standpoint of a bioarchaeologist, who relies on ancient skeletons to piece together history’s complex puzzle, I’ve developed a respect and admiration for the excrement of yore. So let’s take a look at these piles from the past, otherwise known as “paleofeces.”

Everything we consume traverses the long and winding road of our GI tract, providing nutrients and energy along the way before being deposited as waste. Just as people poo today, they were pooing in the past, and occasionally, a lucky archaeologist will stumble upon a pile. Lo and behold, a window to the past is thrown open.

Paleofeces are commonly called “coprolites,” a term coined by geologist William Buckland back in the 19th century as he led the charge in dinosaur discoveries. He not only discovered dinosaur bones, he also identified their monstrous mounds of manure and today, paleontologists around the world devote whole careers to the study of dino dung.

But we’re going to home in on the human version of these exotic treasure troves and explore the variety of information gleaned from ancient turds.

I bet you’re wondering how a pile of poo can be preserved for thousands, or even millions, of years. Well, like any bit of archaeological data, the conditions must be ripe for preservation. In the case of paleofeces, they manage to survive when they become desiccated (dried out) or fossilized (turned to stone). As the poo dries and hardens, its contents become fixed. The poo must then be reconstituted, or restored to its original consistency, which is done using special solutions that help preserve what’s tucked inside. Interestingly, as the poo is reconstituted, not only does it offer up its contents, it also emits its original odor!

Once the poo is soft and pliable, the investigation can begin.

For anyone who has ever eaten whole-kernel corn, you know that the kernels magically reappear in your excrement (my fellow firefighters referred to them as “tracers”). The study of paleofeces works on this same principle, for ancient poo reveals a lot about the foods that were consumed, especially plants. Pollen helps us identify the plant species, as do the phytoliths, the portion of the plant composed of silica, which resists decay (and digestion). And why are plants important? Plant consumption not only tells us about diet (what people were eating), and environment (what conditions they experienced), it also helps us reconstruct when domestication took place in different parts of the world. By identifying the plants and then dating the poo, we can obtain the “when” and “where” of agriculture.

But plants aren’t the only things recovered from paleofeces. In many cases, critters are lurking from within, mainly in the form of parasites.

Parasites are organisms that take up residence on or within a host, drawing nutrients (at the host’s expense) in order to stay alive and reproduce. Since many parasites occupy the gastrointestinal tract, they are passed out of the body during defecation where they can then be spread to new hosts (which is why hand washing is so vital). When parasites are discovered in paleofeces, they provide information about health and nutrition among ancient populations (it’s hard to be healthy with a belly full of worms). The study of ancient parasites has become so popular it has now evolved into its own specialty: paleoparasitology

Along with plants and parasites, we also find the bones of animals, and even DNA, when we’re lucky.

So where do we find these valuable little nuggets? They show up in the ground, in ancient latrines, in mummified corpses, and even in the bog bodies of northern Europe. And they’re providing a vast array of information about our past.

Evidence for people in North America was pushed back a few thousand years when a fourteen-thousand-year-old pile of poo was discovered in Oregon. And the earliest evidence for the domestication of dogs came from human coprolites in Texas, dating to over nine thousand years old. Unfortunately, the dog ended up on the menu, but it’s still a cool discovery. And in a bit of poetic justice for critters, the oldest known human hair was recently discovered in of all things, a crusty little hyena turd recovered from a cave in South Africa.

All that from simple dung.

But you don’t have to be an archaeologist to appreciate the value (and beauty) of ancient poo. Thanks to some inventive jewelry designers, you can now adorn yourself or your loved one with dino droppings. So the next time that birthday or anniversary rolls around, say “I love you” with a bit of biological bling.

Who says you can’t polish a turd?...

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