The Meaning of Human Existence (11 page)

The exploration of biodiversity has few friends in the corporate and medical world. This is a serious mistake. Science as a whole loses as a result. Taxonomists do far more than name species. They are also experts and primary researchers on the organisms of their specialty. To them we must turn for most of what is known on nonhuman life, including world-dominant groups such as nematodes, mites, insects, spiders, copepods, algae, grasses, and composites on which our own lives ultimately depend.

The fauna and flora of an ecosystem are also far more than collections of species. They are also a complex system of interactions, where the extinction of any species under certain conditions could have a profound impact on the whole. It is an inconvenient truth of the environmental sciences that no ecosystem under human pressure
can be made sustainable indefinitely without knowing all of the species that compose it, which commonly number in the thousands or more. The knowledge coming from taxonomy and biological studies dependent upon it are as necessary for ecology as are anatomy and physiology for medicine.

Otherwise, scientists easily misjudge which ones are likely to be “keystone” species—those on which the life of the ecosystem is dependent. The most potent keystone species demonstrated in the world may be the sea otter, a cat-sized cousin of weasels that lives along the coast from Alaska to southern California. Because its luxurious fur was so much prized, the species was hunted to near-extinction by the end of the nineteenth century—with a catastrophic ecological result. The kelp forest, a dense mass of algal vegetation anchored on the sea bottom, reaching to the surface, home to a vast number of shallow marine species, and nursery for other species from deeper waters, also mostly disappeared. The cause: sea otters feed heavily on sea urchins, and these spiny invertebrates feed heavily on kelp. When the sea otters were taken out, the sea urchin population exploded, and large sections of the ocean floor were reduced to desertlike surfaces called sea-urchin barrens. When the sea otter populations were protected and
allowed to flourish again, the sea urchins declined and the kelp forests returned.

How can we care for species composing Earth’s living environment if we don’t even know the great majority of them? Conservation biologists agree that large numbers of species are going extinct before they are discovered. Even in purely economic terms, the opportunity costs of extinction are going to prove enormous. Research on just small numbers of wild species has yielded major advances in the quality of human life—an abundance of pharmaceuticals, new biotechnology, and advances in agriculture. If there were no fungi of the right kind, there would be no antibiotics. Without wild plants with edible stems, fruit, and seeds available for selective breeding, there would be no cities, and no civilization. No wolves, no dogs. No wild fowl, no chickens. No horses and camelids, no overland journeys except by hand-pulled vehicles and backpacks. No forests to purify water and pay it out gradually, no agriculture except with less productive dryland crops. No wild vegetation and phytoplankton, not enough air to breathe. Without nature, finally, no people.

The human impact on biodiversity, to put the matter as briefly as possible, is an attack on ourselves. It is the action of a mindless juggernaut fueled by the biomass of
the very life it destroys. The agents of destruction are summarized by the acronym HIPPO, with the relative importance of the agents declining left to right, in this acronym, in most parts of the world:

Habitat loss (H), by far the leading agent of destruction, is defined as the reduction of habitable area by deforestation, conversion of grassland, and that great golem arising from all our excesses, climate change.

Invasive species (I), aliens that cause damage to humans or the environment or both, create global havoc. Their variety and number in every country for which counts have been made is increasing exponentially. Despite improving quarantines, the immigrants pour in faster and faster. South Florida now has a varied fauna of parrots where none existed before (except for the now-extinct Carolina parakeet), and two species of pythons, one each from Asia and Africa, that compete with American alligators at the top of the food chain.

Hawaii is the American capital of extinction, having lost more of its endemic plants, birds, and insects—those species and subspecies found nowhere else—by a wider margin than any other state. Its endemic species of birds are down to forty-two from the original seventy-one estimated present when the first Polynesians came ashore over a thousand years ago. They have been hammered at two levels. The accidental introduction of mosquitoes
in the nineteenth century allowed the spread of avian pox. Feral pigs, while rooting through the soil of the upland forests, churn the ground into foul muck and silt, which eventually helps create long-lasting pools of water ideal for mosquito larvae.

Equally deadly on a global scale has been the human-aided transport of the chytrid fungus
Batrachochytrium dendrobatidis
, a parasite of frogs, into the American tropics and Africa. The parasite evidently travels in aquaria containing infected animals. The fungus spreads through the skin and, because frogs breathe through their skins, suffocates its host. Scores of frog species have been extinguished or threatened with extinction.

And if this were not enough, there are invasive plant species capable of destroying a complete ecosystem. Such is the velvet tree
Miconia calvescens
, a beautiful small tree of the American tropics grown widely around the world as an ornamental. On the islands of Polynesia it has also proved to be a menace capable, when not controlled, of growing to full size and in stands so dense as to crowd out all other plant species and most forms of animal life as well.

Pollution (first P in the HIPPO series) has inflicted most of its damage to fish and other life in freshwater systems. But it is also the cause of the more than four hundred anoxic “dead zones” in marine waters
that receive contaminated water from upstream agricultural land.

Population growth (the second P) is actually a catalytic force of all the other factors. Damage will not be so much from the growth itself, which is expected to peak by the end of the century, but rather from the rapid and unstoppable ascent in per capita consumption worldwide as economies improve.

Finally, the role of overharvesting (O) is best illustrated by the percentage of global decline in the catch of various species of marine pelagic fishes such as tuna and swordfish from the mid-1850s to the present: 96 to 99 percent. Not only are these species scarcer, but the individual fish caught are on average also smaller.

Of course there exists an earnest worldwide effort to map and save biodiversity. The Census of Marine Life and Encyclopedia of Life programs have made available on the internet most of what we know of Earth’s species. New techniques are helping to discover new species and to identify those already named, with increased speed and precision. Most notable among these methods is barcoding, the identification of species by reading short sections of highly variable DNA. Global conservation organizations such as Conservation International, World Wildlife Fund–U.S., and the International Union for Conservation of Nature, along with a host
of governmental and private organizations, are doing all they can—often with heroic exertions—to stem the hemorrhaging of biodiversity.

How much has this effort achieved? In 2010 a team of experts drawn from 155 research groups around the world joined to assess the status of 25,780 vertebrate species (mammals, birds, reptiles, amphibians, and fishes). These were classified on a scale from safe to critically endangered. One-fifth of all the species were found to be threatened, with 52 on average each year descending one step on the scale toward extinction. Extinction rates remain 100 to 1,000 times higher than before the global spread of humanity.
Conservation efforts made prior to the 2010 study were estimated to have slowed deterioration by at least one-fifth of what it otherwise would have been
. This is real progress, but still dismally short of stabilizing Earth’s living environment. What would we think if told that the best efforts of (underfunded) medicine during a fatal pandemic had allowed only about 80 percent of the patients to die?

The remainder of the century will be a bottleneck of growing human impact on the environment and diminishment of biodiversity. We bear all of the responsibility of bringing ourselves and as much as possible of the rest of life through the bottleneck into a sustainable edenic existence. Our choice will
be a profoundly moral one. Its fulfillment depends on knowledge still lacking and a sense of common decency still not felt. We alone among all species have grasped the reality of the living world, seen the beauty of nature, and given value to the individual. We alone have measured the quality of mercy among our own kind. Might we now extend the same concern to the living world that gave us birth?

IV

IDOLS OF THE MIND

H
UMANITY
’
S INTELLECTUAL FRAILTIES

IDENTIFIED BY
F
RANCIS
B
ACON, IN ONE OF

THE PRINCIPAL ACHIEVEMENTS OF THE FIRST

E
NLIGHTENMENT, CAN NOW BE REDEFINED BY

SCIENTIFIC EXPLANATION.

12

Instinct

T
he French writer Jean Bruller (pen name Vercors) was on the right track when, in his 1952 novel
You Shall Know Them
, he declared, “All of man’s troubles have arisen from the fact that we do not know what we are and do not agree on what we want to be.”

In this part of our journey, I propose to come full circle and with the aid of general biology attempt to explain why human existence is such a mystery, and then expand on ways that mystery might be solved.

The human mind did not evolve as an externally guided progression toward either pure reason or emotional fulfillment. It remains as it has always been, an instrument of survival that employs both reason and emotion. It emerged in its present form from a labyrinth of large and small steps, in a series that is one out of millions possible. Each step in the labyrinth was an accident of mutation and natural selection acting on the alternative
forms of genes that prescribe form and function of the brain and sensory system. By accident in the to and fro, it brought the genome to its present level. At each step the evolving genome could easily have veered onto one different pathway or another, hence specialization of the organism to a different kind of brain and sensory system. The chance of eventually reaching the human level would at each step have sharply declined.

The particular conglomerate of reason and emotion we call human nature was just one of many conceivable outcomes, an autonomously generated product reached first out of many kinds that could have achieved a brain and sensory system at the human level of capacity.

Such is the reason our self-image as a species has always been distorted by deep biases and misconceptions, the “idols” of superstition and imposture described by Francis Bacon four centuries ago. They were imposed upon us not by cultural accidents, the great philosopher said, but by the “general nature of the mind.”

And so it has ever been. Confusion has always abounded. For example, as late as the 1970s the orientation of the social scientists was primarily toward the humanities. Their prevailing view was that human behavior is primarily or even entirely cultural, not biological in origin. There exists, the extremists among them claimed, no such thing as instinct and human
nature. By the end of the twentieth century the orientation flipped toward biology. Today, it is widely believed that human behavior has a strong genetic component. Instinct and human nature are real, although how deep and forceful remains under discussion.

Both views, it turns out, are half wrong and half correct, at least in extremity. The paradox created, often described as the nature-versus-nurture controversy, can be solved by applying the modern concept of human instinct, as follows.

Instinct in humans is basically the same as instinct in animals. However, it is not the genetically fixed, invariant behavior displayed by most animal species. A classical textbook example of the latter is territorial defense by males of the three-spined stickleback, a fish found in fresh and marine waters throughout the Northern Hemisphere. During the breeding season each male stakes out a small area which he defends from other males. At the same time the male develops a bright red underside. He attacks any other fish with a red belly, hence a rival stickleback male, that enters his territory. Actually, the response is even simpler than “other fish” implies. The male has no need to recognize the full image of a real fish in order to be activated. His relatively small brain is programmed to respond just to the red belly. When experimenters cut out pieces of wood in a near circle and
other unfishlike forms and painted a red spot on them, the models were attacked with equal vigor.