Survivors and the Terminator

The story of biological evolution recounts the ways that most plants and animals have changed over time as small bodily variations improved their odds of survival. But what about those species, fitted successfully to stable environments early on, that have changed very little? Are any such ancient species (besides the microbes) still around today?

Yes. In Survivors: The Animals and Plants that Time Has Left Behind, Richard Fortey tracks down some present-day creatures that look much like their fossilizeds ancestors from millions of years ago. Oddly, their stories of sameness impress me with as strong a sense of evolution’s power as the stories of other species, including ours., that have changed to adapt.

Horseshoe crabs, after half a billion years, still crowd the beach. (delaware-surf-fishing.com)

Horseshoe crabs, after half a billion years, still crowd the beach.
(delaware-surf-fishing.com)

In the opening chapter, Fortey is on a beach in Delaware on the night of the annual horseshoe crab orgy, when thousands of male horseshoe crabs come ashore to clamber on top of the females. Horseshoe crabs have  been scrambling up beaches for 500 million years.

In the darkness along Delaware Bay the scratching percussion of the crabs provides an unmusical accompaniment on an imaginary journey backwards in time: to an era well before mammals and flowering plants; a time before the acme of giant reptiles, long before Tyrannosaurus; backwards again through an extinction event 250,000,000 years ago that wiped nine-tenths of life from the earth; and then back still further, before a time of lush coal forests to a stage in the earth’s history when the land was stark and life was cradled in the sea.

firmoss (newfs.s3.amazonaws.com)

Four hundred mya, plants like this Norwegian Huperzia moved from the water to land and were among the first to acquire the crucial, stiffened water-conducting tubes that enabled them to stand upright and compete for light.
(newfs.s3.amazonaws.com)

In the other chapters, Fortey describes the velvet worm in New Zealand, the lovely Norwegian fir moss, the not-so-lovely lungfish. The photo captions here mention their particular keys to adaptive success.

It helps that their environments have changed very little. “Survival is about endurance of habitat.” One habitat that endures is the tidal flat, where the shallow sea meets the muddy shore. Organisms here can burrow, find oxygen in the water and air, find food through filtering or scavenging. Here are horseshoe crabs, snails, small fish, many plants. “This habitat does seem like a good place to be for an organism with conservative tendencies. If its own place survives, then so will the beast. It is the right place to weather mass extinctions that affect many other environments more severely.…Stick-in-the-muds last longest.”

As for the durable species themselves, a few characteristics recur. “Many…seem to have long life spans.” Horseshoe crabs take a decade to mature. And some enduring animals invest more resources in fewer progeny by producing “relatively large eggs or few offspring.” But there are no fool-proof formulae. “[T]he luck for old timers will eventually run out. It always does.”

lungfish (media-web.britannica.com)

In Australia, Fortey finds the lungfish that dates back 400 mya, “the great survivor among the vertebrates, the animals with backbones.” With lungs, these sea creatures, in the transition to the land, can gulp air when the river runs low on oxygen.
(media-web.britannica.com)

What about humans? When will our time run out? Fortey doesn’t make guesses, but he has a hard label for us.

[Early man] may have hunted edible mammals and birds to the point of obliteration even in his earliest days; he was the first species that deserves to be called the Terminator….The extinction event that is happening right now is the first one in history that is the responsibility of a single species. There’s no meteorite this time, no exceptional volcanic eruptions, no ‘snowball earth,’ just us, prospering at the expense of other species.

He is confident about the survival of only one type of organism. “I am not worried about the survival of bacteria. They will be there to rot down the last bodies of the last humans, and then the wheel of life will have turned full circle.” So ends the book.

 

Plants as Aliens

Plants are so familiar to us that we don’t see them very well. We look at them and think about them according mostly to how we use them—for food and beauty. To shift our perspective, I’ll look at plants as if they were strangers from another planet, as plant-aliens. Making them weirder may make them more vivid.

  • Plant-aliens don’t eat anything. They make their own food. For that purpose they anchor themselves to a water source and grow their own solar panels.
  • Plant-aliens follow a clock that is geared only to the sun light and the seasons. Small plants push out leaves and flowers quickly in early spring so that they can catch maximum sunlight before the slower growing leaves on the trees above them plunge them into shade.
  • Unlike the many animals that cooperate so they can secure food, plant-alien food makers have little reason to be social. They don’t appear to react to each other at all as they seek out the sun. In fact, however, research is showing that their root systems commune with fungi about soil conditions and they share nutrients.
  • Many plant-aliens are giants. They tower over all animals.
  • Through their sophisticated plumbing and evaporation mechanisms, tree-aliens pull water up long distances without using any kind of pump. Animals, on the other hand, must all use small pumps just to keep fluids moving inside their fragile bodies.
  • Life below freezing (blendspace.com)

    Life below freezing
    (blendspace.com)

    Plant-aliens survive sub-freezing temperatures that last for weeks or months. They get as cold as the frozen earth around them. Animals can’t survive if they get that cold; hibernating animals cling to a slow metabolism that keeps them above freezing.

  • One process that plant-aliens do share with animals is sexual reproduction. Their equipment for doing so, however, is a little kinky. An individual plant-alien may contain flowers with structures that are male or female or both or that change from one to the other.
  • Plant-aliens breathe in carbon and exhale oxygen. Animals do the reverse.
  • Plants-aliens have successfully colonized the earth. They occupy the coldest and hottest zones, they outnumber animals and they are both larger and smaller than we are. And we animals are at their mercy for our food and oxygen.*

Plants are so different from us and so impressive that it’s actually not too difficult to portray them as aliens. And after that exercise, it’s pleasant to see them again as our comfortable companions and allies. I wonder if they feel the same way about us.

 

*With appreciation for David Attenborough’s The Private Life of Plants (1995)

Steven Pinker on Disgust, Sex, and Happiness

Hearts and brains. Mind and body. We are quite sure that our thoughts take place in our heads. But what about our emotions? Sometimes we locate them in our hearts, sometimes vaguely in our bodies.

But Stephen Pinker in his terrific 1997 book How the Mind Works explains that most of our moods and bodily reactions take place in the mind. He describes them as “modules” in a computer-like brain, sensation-generating programs that have evolved to keep us alive and reproducing. Here I’ll highlight a few of Pinker’s explanations of emotions and sensations that are anchored fully and partly in, and maybe beyond, our brains.

Disgust and Sex Two strong emotions, disgust and lust, are fully the products of evolution going back millions of years.

“Disgust is a universal human emotion” (Kindle location 7865), Pinker writes. Its universality is a sign of how thoroughly we are programmed to resist eating animal parts that might contain infectious microorganisms or other toxins. Humans are disgusted by the smell, the sight, or the even idea of eating most animals and animal parts. “The nondisgusting animal parts are the exception. …Many Americans eat only the skeletal muscle of cattle, chicken, swine, and a few fish” (7903). Every other animal is a source of contamination. We won’t drink a beverage stirred with a flyswatter, even if the flyswatter is brand new. We “find a sterilized cockroach every bit as revolting as one fresh from the cupboard.…People won’t eat soup if it is served in a brand-new bedpan….You can’t pay most people to eat fudge baked in the shape of dog feces.”

Such reactions make no rational sense. With rare exceptions, food today is safe. But just try to eat soup from a new bedpan and feel how loudly your bad-food alarm starts blaring, still set to several million years ago.

Changing the locks. (www.telegraph.co.uk)

Changing the locks.
(www.telegraph.co.uk)

As for sex, we think we know exactly what its purpose is, one that we share with almost all living things. But here’s Pinker.

Why is there sex to begin with?…Why don’t women give virgin birth to daughters who are clones of themselves instead of wasting half their pregnancies on sons who lack the machinery to make grandchildren and are nothing but sperm donors? Why do people and other organisms swap out half their genes for the genes of another member of the species, generating variety in their offspring for variety’s sake? It’s not to evolve faster, because organisms are selected for fitness in the present. It’s not to adapt to environmental change, because a random change in an already adapted organism is more likely to be for the worse than for the better….The best theory…is that sex is a defense against parasites and pathogens (disease-causing microorganisms). …[Your body’s defenses against germs evolve, but the germ’s tricks for evading those defenses evolve much faster.] Sexual reproduction is a way of changing the locks once a generation. By swapping half the genes out for a different half, an organism gives its offspring a head start in the race against local germs. (9577)

To most people, the evolutionary function of disgust makes some sense. But the idea that sex too plays a role in our resisting disease boggles the mind. The sensation itself is no reliable guide to its evolutionary function, according to Pinker.

Happiness Another important emotional experience has thin roots in evolution but has held a place in human culture and vocabulary for at least a couple of thousand years. But it too, understood scientifically, is not what we expect. This is happiness.

Happy moment (www.images.wisegeek.com)

Happy moment
(www.images.wisegeek.com)

Pinker writes that it might seem at first that happiness serves as an incentive to spur us on towards those conditions that are biologically good for us. These conditions include being “healthy, well-fed, comfortable, safe, prosperous, knowledgeable, respected, non-celibate, and loved” (8097). Set these as your steps towards happiness and you will become an evolutionarily successful human specimen. This certainly has been my own view of the adaptive function of happiness.

The trouble, Pinker points out, is that happiness doesn’t actually continue for the period of time during which we are enjoying any of these cheerful states. In fact, the longer that any condition persists without change, whether it is illness or health, modest income or prosperity, celibacy or marriage, the more likely we are to drift toward a middling, default attitude that we describe as feeling “content” or “satisfied.”

In reality, we usually describe ourselves as “happy” at those times when we succeed in achieving more than we already have (as the result, for example, of a professional reward) or when we find out that we are a little better off in some way than those around us. Happiness, it seems, is rooted in comparison and newness. For Pinker, this makes it a rather dismal treadmill, an elusive, fleeting, bubbly emotion that was never cut out to serve as the goal for one’s entire life.

Self, Consciousness, and Free Will Finally, in the last pages of his book, Pinker writes about some philosophical puzzles that people have never been able to wrap their minds around fully. These are such phenomena as the self (the “I” that we are so aware of), consciousness (our awareness, and our awareness of our awareness) and free will (we insist that our choices and decisions are up to us).

Too much for the computational mind to handle. Edvard Munch's The Scream (www.fisheaters.com)

Too much for the computational mind to handle. Edvard Munch’s “The Scream”
(www.fisheaters.com)

For Pinker the reason these are such enigmas may be simply that “the mind of Homo sapiens lacks the cognitive equipment to solve them. …Our minds evolved by natural selection to solve problems that were life-and-death matters to our ancestors, not to commune with correctness or to answer any question we are capable of asking” (11570). Such mysteries as the self and free will are holistic phenomena of a kind that does not lend itself to being understood by “the computational apparatus that natural selection has fitted us with” (11639), an apparatus that works methodically from parts to the whole, example to category, cause to effect. Perhaps such a mind just cannot analyze such sensations as the experience of  being alive and being ourselves.

In summary, for Pinker, emotions and sensations are not matters of the heart. Their roots lie in the evolution of the brain, the interaction of brain and culture, and a holistic awareness beyond the brain itself.