Life's Glow

This time of year in temperate regions, many harken the arrival of firefly mating. Their chemically produced light appears like tiny lanterns floating over the landscape.

Hotaria parvula of Kurayoshi
by hm777

In their mating ritual, fireflies emit bioluminescent light from their abdomens during twilight.

Mating is a curiosity. In a summary account of more than a billion years of an evolutionary life force, Carl Sagan and his spouse Ann Druyan, explore the ever-elusive purpose of life:

“Fireflies out on a warm summer's night, seeing the urgent, flashing, yellow-white phosphorescence below them, go crazy with desire; moths cast to the winds an enchantment potion that draws the opposite sex, wings beating hurriedly, from kilometers away; peacocks display a devastating corona of blue and green and the peahens are all aflutter; competing pollen grains extrude tiny tubes that race each other down the female flower's orifice to the waiting egg below; luminescent squid present rhapsodic light shows, altering the pattern, brightness and color radiated from their heads, tentacles, and eyeballs; a tapeworm diligently lays a hundred thousand fertilized eggs in a single day; a great whale rumbles through the ocean depths uttering plaintive cries that are understood hundreds of thousands of kilometers away, where another lonely behemoth is attentively listening; bacteria sidle up to one another and merge; cicadas chorus in a collective serenade of love; honeybee couples soar on matrimonial flights from which only one partner returns; male fish spray their spunk over a slimy clutch of eggs laid by God-knows-who; dogs, out cruising, sniff each other's nether parts, seeking erotic stimuli; flowers exude sultry perfumes and decorate their petals with garish ultraviolet advertisements for passing insects, birds, and bats; and men and women sing, dance, dress, adorn, paint, posture, self-mutilate, demand, coerce, dissemble, plead, succumb, and risk their lives.

To say that love makes the world go around is to go too far. The Earth spins because it did so as it was formed and there has been nothing to stop it since. But the nearly maniacal devotion to sex and love by most of the plants, animals, and microbes with which we are familiar is a pervasive and striking aspect of life on Earth. It cries out for explanation. What is all this in aid of? What is the torrent of passion and obsession about? Why will organisms go without sleep, without food, gladly put themselves in mortal danger for sex? ... For more than half the history of life on Earth organisms seem to have done perfectly well without it. What good is sex?... Through 4 billion years of natural selection, instructions have been honed and fine-tuned...sequences of As, Cs, Gs, and Ts, manuals written out in the alphabet of life in competition with other similar manuals published by other firms. The organisms become the means through which the instructions flow and copy themselves, by which new instructions are tried out, on which selection operates.

'The hen,' said Samuel Butler, 'is the egg's way of making another egg.' It is on this level that we must understand what sex is for. ... The sockeye salmon exhaust themselves swimming up the mighty Columbia River to spawn, heroically hurdling cataracts, in a single-minded effort that works to propagate their DNA sequences into future generation. The moment their work is done, they fall to pieces. Scales flake off, fins drop, and soon--often within hours of spawning--they are dead and becoming distinctly aromatic.

They've served their purpose.

Nature is unsentimental.

Death is built in.”

― Carl Sagan and Ann Druyan

Male fireflies emit light to attract a female mate. When a female detects a male emitting a recognized and favorable wavelength, she'll respond with her own light to signal her receptiveness to a reproductive liaison.

Summer Night
by Yasushi Kikuchi

Nature is unsentimental, but poetic. Still, "death is built in". Fireflies live for about 10 days.

"Well, what I don't get is why do we exist? I don't mean how, but why.' I watched the fireflies of his thoughts orbit his head. He said, 'we exist because we exist. . .we could imagine all sorts of universes like this one, but this is the one that happened."
― Jonathan Safran Foer

REFERENCES

• Extremely Loud and Incredibly Close, Jonathan Safran Foer, Mariner Books, 2006.
• Magical Photographs of Fireflies from Japan’s 2016 Summer, Christopher Jobson, Colossal, 7 July 2016.
• Shadows Of Forgotten Ancestors: A Search For Who We Are, Carl Sagan and Ann Druyan, Ballantine Books, 1992.
• Why do fireflies glow?, Chanie Kirschner, Mother Nature Network, 7 May 2013.

Life from Comet Collisions

The biosphere covering Earth remains a deep mystery. Where did life originate?

Bioluminescent dinoflagellates lighting a breaking wave at midnight

Earth might well have coalesced from cosmic dust and gas. Billions of years later, a thin raft surrounding Earth teems with co-dependent organisms.

The question of the origin of life is essentially speculative. We have to construct, by straightforward thinking on the basis of very few factual observations, a plausible and self-consistent picture of a process which must have occurred before any of the forms which are known to us in the fossil record could have existed.
— John Desmond Bernal

Where did the ingredients for the simplest unicellular life forms come from? Life's ingredients might have come from comets.

Early Earth was not very hospitable when it came to jump-starting life. In fact, new research shows that life on Earth may have come from out of this world.
― Astrobiology Magazine

Comet Hale Bopp

Comets are vestiges from the formation of our solar system some 4.5 billion years ago. Comets that move into range of space travel, arrive well-preserved from the freeze locker of the outer solar system.

As it travels near the Sun and Earth, a disintegrating comet represents a treasure-trove of hard data about conditions present during the early stages of the solar system.

The composition of comets interests us because scientists posit that life-building organic compounds might have come from icy comets that collided with Earth millions of years ago.

Organic compounds form the basis of proteins and nucleobases (the building blocks of DNA and RNA). Oceans might have been formed from icy comets and asteroids crashing into Earth.

The first comet landing of a robotic spacecraft touched down on Comet 67P on November 12, 2014. Until then, our knowledge of comets came from a handful of flyby space missions

Comet 67P

Comet 67P

The robotic lander Philae bounced to rest on Comet 67P more than 10 years after being launched from Earth by the European Space Agency.

The Philae landing was a historical touchdown on a comet nucleus.

Philae transmitted in-situ data that will enable scientists to determine the composition of the comet's surface material.

Our Quest

Comets were once believed to be harbingers of human destruction by anthropomorphic gods. Our understanding of our habitat and origin accrues through scientific discovery.

Scientific discovery yields physical explanations to mysterious and once feared phenomena. Our appreciation of the far-fetched phenomena of life grows with every scientific revelation.

Our quest to solve the existential puzzle continues.

The origin of life is a complex narrative of improbable events. The lineage of events stretch back perhaps 13.8 billion years to the Big Bang or beyond.


REFERENCES

• How Did Water Come to Earth? Brian Greene, Smithsonian Magazine, May 2013.
• Mission to Land on a Comet, NASA Science News, 31 January 2012.
• The Shocking Source for Life's Origin, Astrobiology Magazine, 27 August 2013.