From Chapter Thirty-Five:
The Balance

The sea turtle hatchling, born in the warm sands of a Florida beach, immediately stumbles to the ocean and throws itself in. Unknowing of the world, unaided by any parent, sought as prey by crabs and birds and perhaps facing its greatest danger from the featureless harshness of the cold waters, the hatchling begins floating among sargassum seaweeds, seeking to orient itself in the currents it will use to navigate as far as Ascension island, thousands of miles distant. Answering some unknowable summons of antiquity the hatchling crosses the ocean alone, accomplishing without any physical technology a feat men and women in boats with radios and radars and turbo diesels and freeze-dried foods and ring-laser gyros have died attempting to accomplish.

Near the end of a life lived on the western shores of Africa the sea turtle answers a second summons, to return to the sands of its birth. This time it cannot float but must swim against the prevailing current. In some haunting way the turtle recalls exactly what it sensed as a hatchling -- the precise successions of currents, wave patterns, salinity changes, and polarity from magnetic north. This is necessary because the goal is to return exactly to the patch of sand on which the turtle first knew the light of the temporal world. North America alone will not do; Florida alone will not do; it must be the same beach, the same feel and smell in every way.

Perhaps the sea turtle is a mere genetic automaton, driven by deterministic amino acid encodings toward a moot goal dropped into its DNA by some past random happenstance that signifies nothing. Or perhaps this journey has meaning.

Perhaps the turtle is willing to swim the breadth of the very ocean in order to experience once again the sweet tastes that accompanied its awakening to life -- the early sensations of youth being the sweetest any living thing can ask to know. Perhaps this allows the sea turtle to end its days having not just existed and processed carbohydrates and excreted nitrogen and grown senescent but lived, taken a small yet noble role in an enterprise that may eventually fill the whole of the cosmos with meaning. Perhaps the turtle is driven not by mindless helixes but by longing -- the longing of life over matter, the most insistent force in all the firmament.

One rare exception in a world of numbing pointlessness? Consider other examples of the profundity of life.

The spotted salamander lives underground almost the entire year. One day in spring when the temperature is at least 42 degrees Fahrenheit and it has rained hard the previous night, every spotted salamander emerges for a night of sporting and mating. When the night ends the salamanders return beneath the ground for another year. The timing of the emergence is always flawless.

Birds want berries for food. Plants want birds to distribute their gene lines by eating berries, flying somewhere, then relieving themselves of a portion of the berries designed to be indigestible: the seeds. Why do berries turn red? As a signal to birds that they are ripe and the time has come to eat them.

Each fall tile yellow pine chipmunk collects and buries seeds of the yellow pine and the bitterbrush, a staple browsing food of deer. Some seeds the chipmunk returns to consume; some seeds the chipmunk forgets about. Forgotten seeds bloom in spring, perpetuating the yellow pine and the bitterbrush, which in turn feed the deer. The seeds have not only been dispersed by the chipmunk, they have been planted.

When a bear hibernates, in some unknown way its body recycles calcium to prevent osteoporosis and reabsorbs urea to prevent bladder failure. Bears can even carry a pregnancy through hibernation, continuing to make the necessary hormones; though in all nonhibernating mammals including people, fasting ends hormone production and causes miscarriage.

The sluggish caterpillar myrmecophilous, an attractive target for wasps, has two nectary glands that secrete a potion ants seem to consider champagne. If myrmecophilous thumps a branch in distress over the presence of a wasp, any nearby ants will rush to defend the caterpillar.

In the tree canopies of the tropical rainforest, star-shaped plants called bromeliads catch precipitation to form puddles. The puddles provide the plants with water, so they need not shoot roots to the ground: they also serve as little ponds for hundreds of other life forms.

Female guppies that live in streams where there are no predators prefer flashy males with bright markings and large fins. Female guppies that live in streams with many predators prefer plain males. Thus under safe conditions female guppies choose genes for attractiveness, to help their offspring get on socially. Under dangerous conditions female guppies choose genes for camouflage' to help their offspring survive by going unnoticed.

The opossum is believed to have existed for at least 60 million years. That is to say the opossum, a delicate thing easily harmed, is far older than the Rocky Mountains, a seemingly indestructible mass of dense minerals hewn from Earth's very continental plates. The whale is thought to have existed at least 12 million years, after somehow evolving from a land animal similar in appearance to a cow. That is to say the whale, a fragile living thing, is far older than the present alignment of ocean currents in which it swims. The sandhill crane seems to have existed for at least nine million years, perhaps making migratory stops along the area of the North Platte River of Nebraska, a favored present-day calling point, much of that time. The North Platte itself is somewhere around 15,000 years old. That is to say the sandhill crane, a fragile living thing today called endangered, is far, far older than the river at which it calls.

'The monarch butterfly, a mere insect, migrates as much as 2,500 miles. Monarch brains no larger than a few grains of sand contain the topographical information necessary to navigate from the northern United States to Mexico. Several generations of the butterflies -- born, metamorphosed, flying, mating, dying -- are required to complete the passage of a family line from summering grounds to wintering area. Just try to guess what forces lead to the development of metamorphic creatures such as the butterfly, which essentially require two separate sets of genetic inheritances favored by two entirely separate circumstances of natural selection.

These are but a few of many, many examples of the wonder and complexity of life. I choose them because they may be less familiar than others. And I choose these two from genus Homo.

In the sediments of a lake near the Greek city of Nikopolis has been found a flint axe that is at least 200,000 and perhaps 500,000 years old. This tells us humans were not just quizzical primates, but tool users with minds already struggling to comprehend the world, an unimaginable length of time ago by our way of thinking.

In 1991 in the Qafzeh Cave near Haifa, Israel, archaeologists found the bones of a young human female delicately interned, arms wrapped around the bones of a neonate -- suggesting mother and infant buried together after both died during childbirth. The bones are at least 100,000 years old. This tells us human beings had already begun to develop spiritual awareness -- were already struggling with the meaning of life and the tragedy of its loss -- an unimaginable length of time ago by our way of thinking.

The rest of this book asks two basic questions. The first is whether people, machines, and nature can learn to work together for each other's mutual benefit, achieving plateaus each alone would be incapable of. The second is whether the ongoing process of life has larger significance or is just something that happened when chance assemblies of amino acids accidentally activated each other.

This second question is in the end the question of the environment.