Friday, March 27, 2015

Fire It Up!

In the mood for a revelation? Ask firefighters how they feel about fire. Their response may surprise you. Firefighters spend their entire careers laying their lives on the line. Whether they’re battling ripping house fires full of toxic combustibles, hiking mile after treacherous mile to combat raging wildfires, or sacrificing it all amidst the horror of a terrorist attack, firefighters are on the front line when it comes to battling the lethal force that is fire. So you might find it curious that firefighters actually love fire.

Are they crazy? (Yes.) Are they obsessed? (Most definitely.) Or are they simply adrenaline junkies? (C. All of the above.). Firefighters are an unusual breed. Think about it - cops aren’t infatuated with the criminals they cuff. Oncologists aren’t enamored of the cancer they annihilate. So how can firefighters love what they spend their whole lives fighting? The answer: because they are human. And there’s something about fire that humans simply adore.

As a firefighter-turned-archaeologist, I’ve spent a lifetime preoccupied with fire. As a firefighter, I saw its lethal side. I waded through charred wreckage, broke the news to grieving loved ones, and saluted the caskets of fallen comrades. As an archaeologist, I’ve explored fire’s positive dimensions: its deep human history, the fundamental role it has played in culture, and the visceral connection we have with this phenomenal force.

Perhaps it’s our ancient association with fire that has so ingrained it in our psyche. Evidence for its use goes back almost a million years, far longer that our species has roamed the earth. Homo erectus appears to have been the first to habitually use fire, and we find their ancient campsites, replete with butchered bones and beautiful stone tools, dotting their primordial landscapes. Fire provided warmth for our ancestors, despite the frozen grip of repeated ice ages, and gave them protection against predators stalking their primitive campsites. Fire provided light during their primal nights and formed the nucleus for social gatherings, where they exchanged information, manufactured tools, created art, and told stories. Fire was a catalyst of human culture.

As modern humans arose in Africa some two hundred thousand years ago, venturing forth to lay claim to the globe, they adopted fire, making it one of the most essential tools in their prehistoric toolkit. But the most important application for fire predated the arrival of Homo sapiens. In fact, we moderns may have never evolved had it not been for the invention of fire’s most essential role: cooking.

Cooking transformed us. The advent of cooking, especially of meat, was pivotal in the evolution of our species. Meat provided the valuable nutrients necessary to fuel our ever-expanding brains, but it was the cooking of meat, along with plants, tubers, and anything else our ancient brethren happened to toss on the barbie, that streamlined our digestive tracts and fueled our giant brains.

Cooking transformed humans because cooking transforms food. If you don’t believe me, hack off a hunk of raw sirloin and give it a chew. When you’re finally able to swallow (about twenty minutes from now), I’m betting you’ll be requesting the rest of that steak “medium well.”

Cooking jump starts digestion. In meat, it does this by breaking down the muscle fibers. Cooking also makes meat safer. The heat of cooking kills off pathogens, such as Clostridium and Staphylococcus, which hide out in undercooked meats just waiting for the chance to sabotage your gut.

Cooking also releases nutrients and calories – not only in meat, but in vegetables, as well. And aside from the nutritional benefits of cooking, most foods simply taste a whole lot better when cooked. Which would you prefer? A raw potato eaten apple-style or a steaming baked spud covered in butter and sour cream? (OK, I’d eat my shoe if it were covered in butter and sour cream, but you get my point.)

Cooking, like fire, drew people together. Even today, humans love to congregate and cook. What’s more fun than hovering around the grill, surrounded by the silky fragrance of cooked meat and wood smoke, or assembling in the kitchen on Thanksgiving, as that golden-brown turkey emerges from the oven? Cooking brings us together, forges social bonds, and encourages sharing – all traits necessary for human society.

As for firefighters, the opportunity to sit down at the end of a busy day and swap stories over a hearty dinner plays a fundamental role in the cohesion and morale of a fire station. And ever since I traded my helmet for a trowel, dinner just hasn’t been the same.

Stay safe out there.

Here's an excellent read on the subject!

Friday, March 20, 2015

Carnivore Kin

Is there anything more annoying than a vegan? Since when did eating a chunk of cheese spell the demise of civilization? Don’t get me wrong, I stand with the v’s on their animal rights platform and abhor the trend in industrial farming. In fact, my precious niece and her lovely wife are vegans and, although I admire their integrity and applaud their dedicated activism, I have a distinct urge to stuff an egg down their throats. I just don’t get the vegans.

As a committed carnivore, I must stand up for the meat eaters. We humans evolved to eat meat. Don’t believe me? Reach over and pry open the jaws of the person next to you. What you’ll see is living proof that we are meant to consume a wide range of foods – many of which had parents. The proof is in our teeth.

You can tell a lot about a critter from its teeth. From paleontology to paleoanthropology, teeth afford a handy way of identifying fossils, be they archaeopteryx or australopithecines, for teeth say a lot about how an organism lived, and, most importantly, what they ate.

Close your eyes and picture a crocodile, preferably with its mouth open. What you should see in your mind’s eye are teeth that vary in size but are all the same shape. The homodontous dentition of a croc is designed for one thing: grabbing flesh, which they do with lethal precision. Crocs don’t chew, thus they have no need for molars. They simply grab hold of that wildebeest, crush and tear what they can, then swallow as big a chunk as possible.

Now picture your own teeth. They come in an array of shapes and sizes, for they have various functions. Our incisors and canines are for biting and tearing, our molars, for chewing. As omnivores, our heterodontous array opens us up to myriad foodstuffs, from seeds and nuts to plants and the all-important meat. And when I say meat is important, I don’t just mean for today’s burgermunchers. The consumption of meat played a critical role in human evolution.

Some of the earliest evidence for meat eating comes from the dusty plains of Gona, Ethiopia, where butchered animal bones dating back to over two and a half million years ago were discovered in 1994. Carnivory was pushed back another million years by a discovery a few years back in nearby Dikika, where a goat-like critter was butchered almost three and a half million years ago. And what benefit would meat eating incur? None, really, unless you’re interested in evolving a giant brain.

Meat eating meant a valuable source of protein for our hominin ancestors, which is critical for certain bodily functions, especially a metabolically demanding brain. Our brains consume about twenty percent of our overall energy intake. By exploiting high-quality foods like meat, our ancestors were able to supply their expensive brains without spending the majority of their day grazing like gorillas. 

Our gorilla cousins are forced to spend endless hours munching their way through the forest in order to obtain the nutrients required for survival. And to process all that vegetation requires an enormous gut, thus their Buddha-like physiques. For the hominins, better foodstuffs meant a reduction in our guts. And since all of evolution is a tradeoff, smaller guts requiring less energy may have freed up fuel to grow our bigger brains. Not only did our guts get smaller, so did our teeth. As our teeth got smaller, so did our faces; thus we lack the forward-jutting snouts of our ancestors.

More meat meant more people. A higher-quality diet, combined with the benefits of cooking (which boosts nutrients and kills pesky pathogens), would have enabled earlier weaning of infants, allowing women to have more babies more often, thereby spreading the human race far and wide.

Meat also fueled our social evolution. Communal hunting instilled cooperative behavior and communication. As populations got bigger, meat on the hoof would have become scarcer, thus the domestication of animals provided a steady supply without the need to hunt. A steady supply meant populations could grow even larger, ushering in complex society, social stratification, and, eventually, industrialization; all made possible because of our love of meat.

So the next time you are enjoying a juicy steak and some disapproving vegan gives you the stink-eye, take heart. If it weren’t for our carnivorous ancestors, we’d still be wandering the African plains with our dinky brains and a fistful of tubers.
Hurray for the carnivores!

Here's a great read on the environmental repercussions of meat eating (a nod to my favorite vegans!)

Join me next week when we explore another "hot" topic in human evolution. Stay tuned! 

Friday, March 13, 2015

The Climb of Your Life

This morning on the radio, I heard one of my favorite songs, Edwin McCain’s I’ll Be, which has a great line in it: "I’ll be better when I’m older…"  It got me thinking about age and perspective. It seems throughout early life, all we wish is to be older. It’s as if we are climbing a ladder and life will truly begin once we reach that next rung. 

So I want you to perform a thought experiment: climb down the ladder and go back in time. Try to recapture your perspective as you ventured forth on your ascent.

When we’re small, all we want is to be big. And the way to get bigger is to accumulate birthdays. That’s why kids will never respond with “four” or “seven” when asked their age. They are “four and a half” or “seven and three-quarters!” Ask any kid and I bet they tack on that imperative fraction. But childhood is not a time to rush. Important things are happening in our little bodies. Although our growth rates are no match for the rapid development of infancy, we will still chalk up about two inches per year until we hit adolescence. Aside from growing, our bones are fusing, our teeth are erupting, and our brains are making critical connections that will help us read, write and express ourselves throughout our lifetimes.

Then comes the day our birthday cakes boast double-digit candles. It’s a magical time, adolescence. Hormones are raging, new hair is sprouting, and suddenly our bodies possess strange and wonderful abilities (especially if you sport a penis). And how do we respond to these mystical metamorphisms? By wanting to be a grownup, so we can take them out for a test drive. As teens we crave independence, the chance to make our own decisions, to be taken seriously as adults. We long to be part of adult society: by voting, serving in the military, and buying beer. As for our bodies, growth is winding down, the last of our molars are settling in (or being yanked by a dentist), and our reproductive capacities are given their final tweaks in preparation for parenthood.

When we finally make it to our twenties, a strange thing happens. Suddenly, the climb accelerates. Those rungs on the ladder go slipping by, greased by some unseen hand. You barely enjoy the freedom of maturity before thirty rears its ugly head. You are shocked to find yourself a parent and can’t quite remember how you got here. You’re saddled with a job, a spouse, and a mortgage, and before you know it, Hello, forty!

Forty arrives and you take a look around from your lofty perch and can’t believe how high you’ve climbed. The air is cooler, it’s easier to breathe, now that you’ve gained some perspective, and many of those imperative life decisions are behind you. Think of all you’ve learned! You look back with wonder at the antics of your youth: the foolish stunts you pulled, the poor judgment you exercised. It’s a wonder you made it this far. And just as you’re settling into this comfy locale, fifty arrives and practically knocks you from your rungs.

How can I be half a century old? you ask yourself. Impossible! Why, just yesterday, I was graduating from high school. How could this much time elapse without my noticing? And as for that view from the ladder - we’re talkin’ nosebleeds! The horizon stretches before you in a hazy blur, the objects on the ground, miniscule. You think back to your previous ideas of fifty and realize you were wrong all along. Fifty's not old! you tell yourself. Sixty, maybe, or seventy, if I’m lucky to make it that far. Besides, if I live to be one hundred, I’m only halfway there! Take a deep breath…

As someone who recently bid farewell to her forties, I cannot lend further perspective on the ladder of life. I’m still climbing, careful as I go. The best advice I can give is to enjoy each and every rung. Yes, you’ll be challenged along the way, by love, loss, and hardship, but the higher you go, the luckier you are. 

Although the rungs of our youth grow small beneath our feet, always remember: the view from the top is mighty fine.

I’ll be your crying shoulder
I’ll be love’s suicide
I’ll be better when I’m older
I’ll be the greatest fan of your life….
                        Edwin McCain

Here's a wonderful article on the evolutionary process of aging, if you're in the mood for a little light reading!

Friday, March 6, 2015

Welcome to the Gun Show

There's nothing more striking than well-defined muscle. The firm bulge of biceps, the ropey thickness of quads, the ravishing ripples of six-pack abs. Few things compare to the beauty of lean muscle. In fact, I’m willing to overlook certain character flaws (kleptomania, bizarre fetishes, or – god, forbid – an aversion to hockey) in exchange for a ripped physique.

Not only is muscle beautiful, it’s also delicious. You may not give it much thought, but each time you bite into a juicy burger, feast on a platter of wings, or tear into a pile of chops, you’re ingesting the muscle of some critter, be it beef, bird, or swine. Let’s face it, muscle rocks.
So to pay homage to the magnificence of muscle, let’s explore these wondrous tissues and the many roles they play in our bodies.

Were we to inventory the 600-plus muscles that make up the human body, it would take the better part of the day. That’s because muscles come in an array of forms and sport tongue-twisting names based on their characteristics. Some are named for their size, such as the largest in the body, the gluteus maximus, which you are probably sitting on. Some are named for their shape, like the deltoid, because of its triangular silhouette. And some derive their name from the direction in which they run, like the beautiful rectus abdominus that extends vertically along the belly, forming those lovely little cans within the six pack.

The body contains three different types of muscle. Skeletal muscle is what gives the body its beautiful design. These voluntary, striated muscles move our bodies by manipulating our skeletons. By pulling on bone, skeletal muscle enables us to walk, run, blink and smile, swivel our heads, rotate our arms, and contort our bodies in myriad ways. Every movement is made possible through the contraction of these amazing fibers. And the anchor points for many of these muscles sculpt our skeletons, for wherever you have muscle pulling on bone, you have a bony prominence on which the muscles gain purchase. The larger the muscle, the larger the attachment site. So as you work out, you’re not only building muscle, you’re building bone, as well.

Just as skeletal muscles move our skeletons, smooth muscle, otherwise known as visceral muscle, also plays a role in movement, but on a much finer scale. The blood coursing through our vessels, the food moving through our digestive tract, the air entering our lungs – each movement is dictated by our brain, coordinated through our nervous system, and carried out involuntarily via these rarely contemplated, seldom seen muscles. Smooth muscles lack striations and are relatively weak. But although skeletal muscles get all the attention, smooth muscles are the true “movers and shakers” of our body systems. They deserve a bit more respect.

The third type of muscle drives the core of our being: the heart. Cardiac muscle is a bit of a hybrid. It shares some similarities with skeletal muscle, some with smooth. It has striations (like skeletal muscle) and is controlled involuntarily (like smooth), but cardiac muscle can do something no other muscles in the body can do: generate a pulse. 

Specialized cells within the heart generate electricity, causing the cardiac muscle to contract. Cardiac muscle cells are arranged so that they overlap, forming a continuous web through which the electrochemical signals can pass. This causes the muscle to contract in a wave, drawing blood in, pushing blood out. And it’s this beautifully synchronous motion that produces the apex of all life sounds: the heartbeat. Your heart will beat on average one hundred thousand times per day, thirty-five million times per year, and more than two and a half billion times during your lifetime (depending on your longevity, of course). That’s a lot of pumping, which explains why a heart can wear out and why it’s so important to keep it healthy.

The muscles in your body make up about half your overall weight. And because they are denser than fat, a fit individual can outweigh his unfit counterpart (and look a whole lot better doing it). And for those of you who have recently fallen out of the habit of working out, take heart: it takes twice as long to lose muscle as it does to gain it, so get up and get lifting! Muscles are fast learners with great memories.

Although our skeletons form the scaffolding on which our body systems are built, it’s the muscles that bring our skeletons to life. Muscles move us, sustain us, and enable us to express ourselves in numerous ways, from simple gestures (a touch, a wink, a smile) to wondrous physical feats (walking, running, and lifting). So treat your muscles as you do your favorite pet: nurture them, nourish them, and give them plenty of exercise. They’ll repay you with a lifetime of unconditional love.

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Bodies in Motion
Size Matters
Hot and Cold