The Fear Factor Page 18
* This procedure was conducted in patients with epilepsy in whom depth electrodes had been placed to enable their physicians to localize the origins of their seizures.
6
THE MILK OF HUMAN KINDNESS
HER WIDE, PALE belly scrapes across the sand as she heaves herself forward. Her thin, formless legs struggle for purchase, but her shoulders are strong. Again and again she pulls herself onward, gaining a few inches each time. The going is slow. The sand slopes unrelentingly upward, and her body weighs over 200 pounds. It leaves a ragged trench in the sand behind her, one that is easily visible even by moonlight. She stops often to rest. At last, about half an hour after first emerging from the ocean, she reaches her destination: the edge of the north Florida beach where the flat-packed sand yields to sugary heaps shaded by stalks of sea oats and creeping purslane. She has seen this spot before, although not for many years, and never from quite this vantage point. But she’s certain it’s the right place. After a pause to recoup her energy, she settles herself in and begins to dig.
She isn’t seeking treasure, nor would she know what to do with it if she found any. She’s here to build a nest. Inside, she will deposit dozens of rubbery, Ping-Pong ball–shaped eggs containing the embryos of her children, just a few of the thousands of loggerhead sea turtles she will produce over her lifetime.
The nest ready, she positions herself above it. The leathery tube of her cloaca bulges as the first egg of the clutch pops from it, shiny with fluid, bouncing off the side of the pit before coming to rest at the bottom. Dozens of siblings tumble out after it in succession, soon burying it. She never gives the gleaming pile so much as a glance. When her oviduct is empty and the pit is full, she flips sand back over the nest in a chaotic spray that coats her own head and shell as well, until the eggs are hidden from view and protected from the sun and wind and gulls and crabs. Afterward, she tamps the pile into a firm lump with the underside of her shell. It doesn’t look like much, but all this spraying and tamping is a significant moment in the lives of her offspring, as it represents the only care they will receive from their mother. Her job complete, she drags herself laboriously back down to the sea, where she disappears beneath the surf along with the last thoughts she will ever give to her babies.
Assuming this is a typical loggerhead nest, it holds about 115 eggs. Many of them will never hatch, some because they were never fertilized. Others will succumb to any of the various hazards that can befall a two-inch-long baby developing unattended in a shallow pit in the sand for several weeks, including being killed by fire ants or crabs or being discovered by poachers or overheating or getting flooded during a storm surge. Of the ones that do hatch and manage to dig their way straight up through a foot of eggs, fellow hatchlings, and packed sand, plenty will never make it to the water. Some will become disoriented by the bright lights of beachfront hotels and die of dehydration. Others will get picked off by shoreline predators like raccoons and gulls. Those that do reach the ocean will have a fighting chance at survival, but they remain so tiny and so vulnerable and face so many obstacles that nearly all of them will ultimately die young too. It’s estimated that only one of every 1,000 loggerhead babies reaches adulthood—that’s a one-in-ten chance that even a single hatchling from this nest will survive to maturity. No wonder their mother didn’t bother getting sentimental about them.
I encountered these hatchlings several weeks later and was not as lucky. If anything, “sentimental” underplays my response to them. This fact—that the same baby turtles could be forgotten and left quite literally for dead by their own mother and also be the object of profound and faintly embarrassing sentimentality from a passing human—is deeply intertwined with, and essential for understanding, the origins of humans’ capacity for altruism.
It was early July when my family and I recently visited my in-laws in Ponte Vedra Beach, Florida. That happens to be hatching season in a prime loggerhead nesting area. Turtles who lay eggs there are fortunate to have all of their nests recorded and monitored by the stalwart volunteers of the Mickler’s Landing Sea Turtle Patrol, a local conservation group. Every spring and summer, volunteers patrol four miles of coastline for signs of turtle nesting. When they spot telltale crawl marks ending in packed-down lumps of sand, they pound wooden stakes into the sand around the nest and scrawl on them the estimated date the eggs will hatch. The patrol’s policy is to wait until three days after the first hatchlings emerge from a nest, then dig up anything that remains to log how many eggs were laid and the fate of each. Was it fertilized? Did it hatch? Did the turtle successfully exit the nest? The best part of a dig is that anywhere from a few to a few dozen turtle hatchlings that have not yet dug their way out are usually unearthed, and are then released by the patrol to make their way to the sea.
My mother-in-law Krista brought me to watch this process with our young daughters on a sweltering Saturday night when a loggerhead nest was scheduled to be dug up. It was about the saddest thing I’ve ever witnessed. Two patrol members found the appointed spot in the sand, and we all circled around. A few hatchlings had emerged three days prior, so hopes were high. One volunteer carried a small red pail into which any new hatchlings would be placed for monitoring before being released. The other volunteer began to dig. Her gloved hands gently carved through the sand as she scraped away layer after thin layer, like an archaeologist, or a sculptor. When the first glimpse of smooth, pale shell appeared, we all held our breath. But it was a dud—an egg that had never developed. Its saggy profile and yellowish tint gave it away. After a few more duds, the first sign of hope appeared. The fragment of a clean, white shell was a sign that at least one hatchling had emerged alive. More fragments followed, as well as some fertilized but unhatched eggs, which the volunteer placed to the side. Eventually, the volunteer’s sliding hands revealed the thing we had most hoped to see: a thin sliver of black no longer than the first joint of my finger—the flipper of a baby loggerhead. But the flipper did not flip. It lay motionless in the sand, lifeless as the shell fragments surrounding it. The volunteer covered it with her hand, hiding it from the ring of hopeful children gathered around, then pried the rest of the body from the sand with her fingers. As she lifted it up, the flipper swung out from under her curled thumb. Carefully, she moved the body to a trough carved in the sand for counting purposes. Another trough already held the eggs, duds, and fragments that had been uncovered. This trough would hold only death.
After a while, there was no point trying to hide the bodies anymore. One still, dark form after another emerged from the sand, turtle upon turtle in various stages of decay—perhaps ten in all. A few were putrid and hardly recognizable. But several, like the first, were still perfect in every feature. My six-year-old daughter, to her credit, was not frightened by them, only curious, so we moved around to the trough to get a better look. I stared for a long time at the first one to be dug up. Its tiny chin rested peacefully on the sand beneath its beaky nose and the large dark whorls of its closed eyes. Its shell was a mosaic of irregular black pentagons fit neatly together. Its front flippers were outsized, like the long limbs of a foal, and their trailing edges bore intricate notches and ridges that I imagine would somehow improve hydrodynamics. Such a perfectly formed thing it was in every detail; a sculptor would weep with joy to create an object of such beauty.
But of course a mere sculpture’s marvels are all external. What lay inside this turtle was, if anything, even more wonderful. Within its chest blossomed an intricate four-chambered heart and lobed lungs, life-giving machines beyond the reach of anything science can yet replicate. Behind its closed lids lay eyes of such complexity that Darwin himself wrote that it seemed “absurd in the highest possible degree” to imagine such a thing evolving through natural processes. A wholly formed brain had pulsed inside its skull—millions of neurons linked together in intricate webs ready to support this turtle’s ability to escape its shell and dig and breathe and learn—maybe even feel. All built for nothing. All built so th
at the sum total of all of these wondrous parts could lay moldering under the setting sun, a checkmark in the patrol’s “dead hatchlings” column. The “live hatchlings” column stayed empty. The horrible waste of it all was overwhelming.
We returned the next evening with hopes for something less depressing, but the first of the two nests to be dug up was even worse. Whereas the first nest had at least born signs of hope and life, including intact fertilized eggs and many more shell fragments than dead hatchlings, the second was an awful avalanche of rotting hatchling carcasses, so many so badly decayed that it seemed unlikely that more than one or two had possibly made it out alive. The verdict was that fire ants from a nearby colony had attacked the nest and killed all the eggs and hatchlings, some still only partway out of their shells.
“This,” said the stoic volunteer by the time she had finally dug to the bottom of the whole horrid mess, “is not a happy nest. I’m so sorry.”
One more nest remained to be dug up before we were to return home to Washington, DC. I hardly had the heart to watch the whole thing again, but the girls begged to stay, so we did. I watched stonily, trying to detach myself from the process this time. The first scrap to appear in this last nest was positive: a shell fragment. More followed. No duds yet, no dead hatchlings. “Don’t get your hopes up, don’t get your hopes up,” I muttered to myself sternly. Then—unmistakable movement! The crescent of a tiny dark flipper flung itself from the sand and scrabbled the air. A thumb-sized head followed, craning toward its first glimpse of the sky, its round, black eyes blinking back the light and crumbs of sand. Jubilation ensued. Children shrieked. My daughter and sister-in-law laughed and hopped up and down. I wanted to laugh myself. It was as winsome and intricate as all the poor motionless ones we’d already seen, but to see its limbs flapping with energy and life was pure joy. More soon followed—eight live hatchlings in all. That is a smallish number, but it felt like a cornucopia. The crowd welcomed each turtle into its sandy new world with a cheer. The volunteers placed them one by one into the red bucket, where they stretched their wrinkled necks toward the setting sun and stepped on each other’s faces while the patrol volunteers finished digging out the nest and making final tallies. They were impossibly cute.
Then it was time to release them. The volunteers aim to interfere minimally with the natural process, so they wouldn’t bring them to the ocean, a thirty-second walk away at the most. Instead, they gently tipped the bucket up next to the nest. The hatchlings had to do the rest themselves.
Oh, the agony and delight of watching them struggle to reach the water! They paddled over the sand like windup toys, their flippers moving in perfect metronomic rhythm—flip-flip, flip-flip, flip-flip, flip-flip. They slowed only slightly as they moved over and around the flotsam and hillocks they encountered. Their certainty of purpose was comically at odds with their miniature bodies. They fanned out as they moved toward the ocean, and the volunteers struggled to keep an eye on all of them and the phalanx of eager watchers ushering them onward, many of us holding our arms out at protective angles. One poor hatchling lost his way repeatedly, heading each time for a thicket of children’s legs. More than once he narrowly avoided being crushed by an errant flip-flop. Each near-miss yielded groans of panic from the onlookers and shouts of: “Move back! Move back!” It was so hard to keep track of all eight. Any attempt to avoid stepping on one risked crushing another. My stomach churned at the thought of one being trodden on—or worse yet, treading on one myself by accident. I didn’t think I could stand seeing another of their tiny bodies go limp, not after having watched them struggle so mightily to reach the lip of the vast churning ocean that was their only hope of survival.
Despite our efforts, tragedy befell the hatchling that kept getting lost. He moved too far from the group, and a gull seized its opportunity to snatch him up. He was carried high in the air while a few people who’d seen it happen screamed invectives at the bird. Was it our screaming? Did the turtle put up a fight? For whatever reason, the gull dropped him. He plummeted down to the sand, fifteen feet at least. A collective gasp. Then, “He’s still alive!” shouted a triumphant volunteer. Not only alive but undeterred, he righted himself and returned to his mission. The onlookers closed ranks around him, ushering him the last few yards of his journey. He was the last one in, but he too made it to the ocean at last. When he reached the waterline and the first gush of bubbling froth hit him full in the face, I swear I saw a look of astonishment in his eyes. He froze for a moment at the novelty of it; yet another incredible event overwhelming his newly formed senses on this, his first day in the world. He quickly recovered and started to paddle, and soon the rushing tide had carried his small form from view.
Walking back to the car afterward, the four of us felt foolishly proud of the hatchlings for making it to the ocean, for having already beaten so many of the odds against them. Everything about this feeling was ridiculous, of course. They weren’t ours. They were reptiles who had been buried in the sand by a turtle, were monitored and dug up by patrol volunteers, and would have made it to the ocean on their own whether or not we had been personally cheering them on and yelling at people not to step on them. If I had happened to visit Florida on a different weekend, I would have never known they existed. So why had I—and thirty other beachgoers—become so instantly protective of and invested in them? So willing to spend time and energy taking what feeble measures we could to ensure that they made it to the water alive—shouting at each other and even at a sea gull (who was just hungry; why did we take the turtle’s side?), holding our arms out like beach bouncers as though this would somehow keep the turtles safe? Why did I feel so delighted watching the hatchlings’ paddling flippers and their sweet, beaky faces, and so terribly hopeful that they might continue to beat the odds and survive? Why did I feel so—there is no other way to put it—sentimental about them when their own mother spared not a single thought for any of them after she had tamped her final tamp over their nest and most likely would have ignored them if she had happened to be on the beach again that evening and seen them scramble past?
The answer traces back many millions of years. The short version is that I am a descendant of creatures called cynodonts, and loggerhead turtles are not. The longer version of this answer may provide the remaining pieces of the puzzle that is extraordinary altruism.
Loggerhead turtles are an ancient species, and a successful one in the scheme of things. They have been leaving their eggs under lumps of sand on beaches around the world for some 40 million years. They and six other existing species of sea turtles, collectively known as chelonioidea, can trace their ancestry back to the progenitors of all modern turtles who emerged more than 200 million years ago during the Triassic Period. That means turtles predate even dinosaurs and birds, who are the dinosaurs’ last surviving descendants. (I know the idea that birds and not turtles are the true heirs of the dinosaurs can seem a little silly—especially if the birds you’re thinking of are pigeons or parakeets—but just watch a great blue heron stalking fish in a stream sometime, its scaly legs and clawed feet parting the reeds while its fierce, pointed head swivels atop its long neck, and it will seem much more obvious.)
Humans and other mammals are the descendants of neither dinosaurs nor turtles, but of hamsterlike creatures called cynodonts whose lineage diverged from other four-limbed animals about 250 million years ago. Like modern mammals, cynodonts were furry and warm-blooded, but they also laid eggs. Together, these traits left them backed into something of a corner when it came to reproducing. To produce warm-blooded babies able to maintain their own body temperatures after hatching would require that the babies be very large—so large that gestating and excreting eggs big enough to contain them would have killed their tiny mothers. The only other option was to produce very small eggs, out of which very small and developmentally immature babies would hatch. But such babies would be so immature that they would be incapable of even supporting their own metabolism without someone keeping them
constantly warm and nourished. They would be, in other words, altricial, which is the biological term for babies born immature, helpless, and dependent. That this word sounds like “altruism” is not a coincidence. Both words are derived from the Latin alere, meaning “to nourish.” Altricial babies can be contrasted with those who are precocial, or developmentally mature and self-sufficient. Human babies are quintessentially altricial, as are the babies of many other mammals and nearly all birds, whereas sea turtles and other reptiles and fish and any other animals capable of showing anything like “certainty of purpose” within minutes of being born are precocial.
So this was a pickle. How could cynodont mothers simultaneously keep their newly hatched babies both warm and fed around the clock? There are only two viable solutions to this problem, and cynodonts came up with one of them. Everything that we know about modern and ancient mammals points to the conclusion that the critical evolutionary development that allowed cynodonts to flourish was that cynodont mothers developed the ability to keep their tiny, altricial young both warm and fed by turning their bodies into food.
In other words, they made milk.
Milk is among the more spectacular evolutionary developments ever to come along. It’s easy to take for granted that mammalian mothers literally dissolve their own flesh and bones and excrete it as food through their nipples because we don’t know any differently. But imagine if you one day discovered that you could shoot hamburgers out of your armpits at will. That’s basically how incredible lactation is. Except milk is even better nourishment than a hamburger. It contains water and salts essential to sustaining life; nutritive fats, proteins, and sugars; various other vital substances, from calcium and phosphorus to the indigestible oligosaccharides that serve as prebiotics in the gut—all served perennially fresh, liquefied, and prewarmed directly from mom.