Life (Re)Cycle

Death breeds life in the world’s most diverse and abundant group of animals.

By Bernd Heinrich | August 1, 2012

Houghton Mifflin Harcourt, June 2012

An inordinate fondness for beetles.” That reportedly was the wry retort of famed British biologist J.B.S. Haldane to a theologian who asked him if anything could be concluded about the Creator’s predilections by studying creation. Haldane was referring to the fact that there are nearly half a million beetle species known on Earth. Having been an avid beetle collector since I was a small boy, I can say I share a certain fondness for the insects.

The diversity of beetles on our planet is amazing, and their behaviors and life histories are just as varied. Nowhere is this more evident than in beetles that dine upon carrion. I find carrion beetles not only wonderfully diverse, but also emblematic of natural cycles of birth and death, the focus of my latest book, Life Everlasting.

As a scientist, I worked for years on the behavior of ravens, the ultimate carcass-disposal specialists, so I was not particularly mindful of the roles beetles play in the recycling process. While large scavengers, such as ravens, eagles, wolves, and coyotes, quickly dispose of animal carcasses in snowy Northern Hemisphere forests, insects take the recycling lead in summer. One group in particular, the burying beetles, or nicrophorines, bury whole carcasses to create an underground smorgasbord for their larvae.

Burying beetles are conveniently attracted simply by setting out a dead mouse. After one beetle discovers a fresh carcass, it wafts an attracting scent to “call” a mate, who arrives in minutes. The pair transports the carcass to a suitable burial site and inters it there.

The fate of large animal carcasses, such as moose or deer, may be similarly quick, and it usually involves large scavengers as well as small. Plant carcasses present a more complicated challenge, however, and the disposal of dying and dead trees may take decades, sometimes even centuries.

Because it is a process that proceeds at a glacial pace, the decomposition of a tree is not as flashy as a hyena killing an ailing antelope, or even the burying of a mouse by a pair of Nicrophorus beetles. So the fate of dead trees and the roles that beetles play in it are therefore easily taken for granted, especially since one seldom sees the beetles as adults—they come, lay eggs, and leave, and the larvae then stay hidden inside for months or years. Yet the beetles use the tree as a food source, and thereby help degrade its tissues and recycle its remains into other organisms as surely as burying beetles do those of mice and birds.

Peel back the bark of almost any tree that is dying or recently dead, and you find the fantastically patterned feeding galleries of beetle larvae, primarily members of the family Scolytidae. Each beetle species leaves distinctive tracks, and each specializes in depositing eggs in a narrow range of tree species. Digging deeper inside the dead tree, one encounters long-horned beetles (Cerambycidae) and emerald beetles (Buprestidae), their much larger larvae move from gnawing the cambium, part of the plant’s vascular system, to burrowing deep into the xylem at the heart of the tree.

Reminded day and night in the summer when I hear the chewing of sawyer beetle grubs in elderly trees, I think of the thousands of gorgeous beetle species in woods the world over that make forest life possible. The topic of disposal of the dead is reminiscent of metamorphosis, and is key to the ecology of life everlasting. Beetles occupy a major hub of it. Haldane had more reason to be correct than he may have realized.

Bernd Heinrich is an internationally recognized scientist and the author of numerous award-winning books, including the best selling Mind of the Raven, Why We Run, and Winter World. He is a frequent contributor to national publications and professor emeritus of biology at the University of Vermont. Read an excerpt of ?Life Everlasting.

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Avatar of: stuart


Posts: 1457

August 1, 2012

OMG! G-d created Scientists, too!?
What would the Creationists say to that!!!??? 

Avatar of: corrigible


Posts: 42

September 1, 2012

Since it is my wonderful good fortune to know a number of "scientists," some being family members, in-laws, researchers, university professors, I have opportunity to know that stereotypes about them are false. Allow me to disclose to any who know a far smaller number of specific individuals, that the majority of the "scientists" I know experience no conflict between science and tolerant religious beliefs. (A genius friend of mine who describes himself as an agnostic, and another who describes himself as an atheist, are highly tolerant of others. And the three of us lament the fact that a small percentage of intolerant individuals give us tolerant ones a bad name. ( : >) A handful of intolerant ones, in fact, seem bent on creating the illusion that there is some sort of contest going on between scientists who all are intolerant, and non-believers in anything spiritual, in trenches, defending all human reason against spiritually open-minded ones who are equally intolerant.

Not so. And, in fact if it WERE so, then many of the individuals I know would be dashing back and forth, firing salvos in opposite directions.

At any rate, the three of us old coots had an enjoyable discussion over lunch one day this week, about what would be involved in the establishing and maintaining of a colony of humans on Mars.

None of us believes such a colony could survive -- even with a constant transporting of need supplies of goods and services from Earth -- unless we were to "dirty up" Mars a bit beforehand or, at least, dirty up a capsule in which the human colonists would live. More particularly, if there were not all sorts of biota present, many conditions we take for granted on Earth would be lacking. Without a few friendly bacteria, beetles, fungi and more, the biosphere in which the colonists would live -- we agreed -- would quicky develop eccentricities of its own. It would evolve in directions of its own. And the probability is great the the successive generations of the colony would rapidly become maladapted to Earth, and might not be able to survive if brought here. Many of our physiological defensive processes, we think, are engaged in on-going homeostases which, in absence of their accustomed oppositions, would turn against their hosts, or against friendly bacteria essential to digestion or other bodily functions, and would morph quickly into what one of us laughingly called "terminators."
In such an evolutionary process, there would be so many adaptations to be made, so rapidly, that processes our human physiologies, and our symbionts (some of which we so take for granted we do not even recognize them as such) would very well "go crazy" and war against the host or one another, to establish a whole new biosphere of king of the mountain contestants. Or, at least, that is what we three believe.
Innumerable precedents for this "belief" can be cited even on such sequestered places as islands. Decades ago, when well-intended medical specialists sought to relief some South Sea Island populations of humans of some of the skin worms and intestinal worms and other kinds of parasites that plagued them. Those people were remarkably free of the kinds of allergies that make life miserable in some 'developed' countries, that those island people, it was thought, would be amazingly healthy when freed from those pesky parasites. But those who do research into relationships between parasitology and immunology know all too well what ensued. Island people who had seemed completely devoid of tendencies to have some disorders such as asthma, certain rashes, sniffles,
itchy eyes, and a whole gaumt of autoimmune disorders, began to develop them. If anything, populations that had been free of diabetes, upon being provided sweet treats, were more inclined to clinical obesity and diabetes and cardio-vascular complications than those on the continents.
Why not, then, just take along to Mars all the good stuff, and leave the mean old bad old germs and pests and bacteria and viruss back here for Earth citizens to cope with?
Well, one problem is, we are not at all certain just exactly which biota are which in all cases.
Earth, it seems, for all its being plagued with things the human brains of scientists are sometimes conceived to be assigned to the task of relieving us from, may be more indispensable to us than pedestrian minds (including intolerant minds) may conceive of, for all their seeming self-certainties about humans, and what we need, and what we would be better off dispensing with, whether scientifically, psychologically, socially, financially, philosophically.
If we were to do away with so many beetles as there are, the result to humanity might be horrendous, might it not? The answer to that is, of course, whatever is the answer to that. But perhaps it was H. L. Mencken (one of my favorite atheists) who put it best when he said words to the effect that: For every issue in human affairs, there is a solution which is simple, and obvious, and wrong.
Science is a coping tool. It is a very useful coping tool. It may even be the best coping tool we humans have to help us muddle along without, in the very name of making things ever better, inadvertently use our findings to make things worse. But there are many things on this earth we humans, on average, tend to take for granted which, if we really had to go somewhere else in the universe and start over again, might not be nearly so expendable as we might think to be simple and obvious.
Or, perhaps my two old retired genius scientist friends and I are just imagining the dynamics of the overall Earth biosphere to be more complex than it is.
For my part, I look at the fact there are so many beetles and ask myself, do we humans need them? Or do we not? My guess is that we might be better off having them around.
You are welcome to disagree. You see, I am very tolerant of opinions other than my own.

Avatar of: Paul Squib

Paul Squib

Posts: 1457

September 2, 2012

one of the most thoughtful replies to this ongoing false dichotomy I've ever encountered - thank you for taking the time to type that out.

Avatar of: corrigible


Posts: 42

September 6, 2012

I would say: FANTASTIC!
Assuming that a scientist is "one who studies nature," then it would be a very naive scientist who would interpret this to mean that a scientist is one who studies "ALL" of nature. One cannot study what one does not yet know -- what one can neither rule in nor rule out on basis of what one knows.
In the 20th century physicists ran into a shocking discovery about "nature." They discovered that at a smaller scale of relative size, there is a whole different set of "rules." (Classical physics poses one set, while quantum physics poses another.)
"Nature," or "reality," was suddenly rendered less narrow than what logical positivism assumed up to then. Now we have a precedent for wondering, "Okay, if there are two non-parallel dynamics, then could there be three? Four? An infinite set of dissimilar rule dynamics?
Are there infinite multiverses?
And even within classical physics, we find certain assumptions highly useful, and call them laws, but find that those laws are merely assumptions.
Science literacy entails knowing the LIMITS of what science has uncovered so far, and entails a taking into account of the fact that the forward-looking assumptions of scientists throughout history have been useful but FLAWED, as would be later discovered. And many of our current asusmptions about where science is HEADED, unless for the first time ever, are likewise flawed.
And the shattering of former forward-looking assumptions has NOT been a result of discovery of what the nature of reality is but, on the contrary, innumerable discoveries of what those things are NOT. Instead of clearer and more precise certainties as to what phenomena "are," our discoveries are a mushrooming of questions, more and more and more questions, the more we discover. For every one new door opened at the frontiers of science today, a number of new questions is RAISED by the newer evidence, NOT RESOLVED... INCREASED. Science literacy is at least as much a matter of accepting that more and more questions are progressively raised than a false assumption that more and more answers are final ones, or are dead-end certainties.
Common sense assumptions about some things -- about absolute zero for instance, or about an absolute vacuum -- have been shattered by strange things that begin to happen the closer we come to experiments aimed at attaining them.
This INCREASE in our awareness of how many unknowns are "out there," developments we haven't even knowledge enough to anticipate we will encounter until we encounter them, suggest that what we are learning in science, more than any other thing, is that the farther we get from everyday human experience the WIDER expands the horizon of what we never even thought to even ASK. The farther we expand the frontiers of science, the more we recognize how little we know. (The full argumentation of this is clear, but would require far more space than appropriate here.)
Take Newton's Third Law. There is no question of whether using it as a tool AT THE MACRO level in engineering is USEFUL.
However, we have never tested that so-called law. To test it, we would have to find a place outside the universe as we know it, to have a place with "no external force acting upon an object traveling in one direction, at one rate of speed. (And, furthermore, our very definitions of relative size and motion fail even a thought experiment when we depart the relativity of space time in which there are, always and everywhere, other frames of reference to relate the subject mass and motion to.)

Just as we have been unable to get close to an absolute vacuum without all sorts of weird things beginning to occur in it... Just as we have not been able to even get close to absolute zero temperature without all sorts of weird things beginning to occur in it... When we find a place outside the universe in which to test Newton's Third Law, what weird non-common sensical surprises will await us there?
Science is WONDERFUL. It is NOT, however, what some logical positivists once imagined to be the study of ALL "reality" or "ALL" nature.
My personal philosophy considers science the highest and best tool for observing, measuring, analyzing, rationalizing on basis of what CAN be and HAS been experienced so far.
Rigorous logic is a wonderful tool, too.
Rigorous logic has a handicap, however. Do you know what that is?
It is "garbage in, garbage out."
If we feed into a logic model things we can only GUESS about, even on basis of the best hard but circumstantial evidence we have to fee into it, the conclusions cranked out by it merely affirm those conclusions.
QUESTION: Meanwhile, what is the best we humans can do with what science provides us?
ANSWER: Come up with some kind of life-living hypotheses to tide us over until the day we know everything for a certainty.
Some of us, and yes many SCIENTISTS choose the assumption that there is a higher intelligence than human intelligence, a whole lot of universe or universes beyond our wildest imaginations much less our certaintites, and, yes, that such higher intelligence pervades everything.
Some of us, and yes, A MINORITY, of SCIENTISTS assume there is nothing or no one beyond what man is "the measure of."
Take your pick. And I'll take mine.
And meantime, my answer to your question is: "FANTASTIC !"

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