Evolution in the new age of extinction

By Constance M. Soja, Professor of Geology

Humans are evolution’s ultimate consumers. As a global society, we are spending more of ecology’s capital assets than are deposited in Nature’s “entangled bank” (apologies to Darwin). With our human population swelling beyond what Earth can sustain — from 6 billion to as many as 8 to 10 billion people in the next 100 years — we have become our planet’s most powerful geologic and evolutionary force. Yet, our existence is inextricably linked with past, present, and future forms of life, a notion that is (somewhat ironically) often reflected in commercial advertising, as I’ll pick up on later.

Many species are undergoing a rapid decline in population and geographic extent. As long ago as 1986, members of the U.S. National Academy of Sciences warned that biodiversity loss is “a threat to civilization second only to the threat of thermonuclear war.” Our ability to crash evolution’s party, it seems, has ushered in a new age of extinction that threatens Earth’s biological richness, perhaps irrevocably. In fact, some scientists have recommended this new “age” be designated the Anthropocene, signifying the immense impact Homo sapiens is having on our planet.

Recent studies have revealed that 60 percent of ecosystems are damaged or severely compromised. While significantly altering and homogenizing nearly 50 percent of Earth’s land, we protect only 8 percent of rainforests — Nature’s tropical pharmacies — and sequester half of the accessible fresh water for our own use. Nearly a quarter of bird species are extinct, and more than 60 percent of major fisheries will require conservation to help depleted stocks recover.

Even the average human lifespan in some developing nations — those in the sub-Sahara, for example — has fallen from 60 to 47 years. As the world’s most gluttonous habitué, we have put ourselves and many of our fellow species over a barrel. We’ve overfished, overharvested, overhunted, overexploited — in a word, overindulged. So it should come as little surprise that our age of consumerism coincides with a new age of extinction.

Perhaps more surprising is how many endangered species are featured in advertisements aimed at consumers around the world. And yet, in featuring these creatures, ads also have the power to build awareness about the importance of other species — directly and indirectly — to our human existence.

Over the years, students in my first-year seminar The Sixth Extinction have collected print advertisements in which wild species are the focal point. We’d discuss how these ads — in humorous, clever, and even quirky or unintended ways — reflect attitudes about endangered species from A (albatross) to Z (zebra): fear and awe, fascination and wonderment, a desire to possess or dominate, and an appreciation for Nature’s purity and elegance.

Thanks to that exercise, I have a burgeoning collection of ads that inspired an idea for a book project to enlighten the sophisticated, savvy spender in all of us. (Many thanks to geology assistants Alyssa Hausman ’09 and Emily Kennedy ’11 for their fact-checking and research assistance on more than 500 ads.) It’s still in the works, but I’ve chosen the title: The Last Good Buy: Evolution in the New Age of Extinction. As a paleontologist, my goal is to heighten awareness about the plight of many wild species as the “Sixth Extinction” gains traction. I’ve chosen to use ads featuring wild species, which provide a huge range of “ecological services” upon which we depend, and about which most people know very little.

Designed to sell us everything from Adobe Acrobat to Ziploc containers, each ad has a hidden message and an important lesson to teach — about ecosystem services, extinction threats, and efforts to conserve these living creatures, some of Nature’s many life-sustaining “commodities.”

My hope is that these images will help to advertise the importance of biodiversity conservation during a time of rapid global change — so that we can continue to derive inspiration and life-affirming benefits from our fellow species before they are lost forever.


 

Woodpecker – Dryocopus pileatus

Woodpecker – Dryocopus pileatus

Woodpecker

Dryocopus pileatus

Evolutionary history

  • The crow-sized pileated woodpecker pictured here is the largest, most easily recognized common woodpecker in North America.
  • More than 200 species are known worldwide.
  • The oldest woodpecker is fossilized in 30-million-year-old Tertiary rocks.

Ecological services and inspirations

  • Ecosystem engineers: Nest cavities, which pileated woodpeckers vacate each year, provide space for other birds such as purple martins, small owls, and chickadees, and for cavity-roosting insects, small amphibians, reptiles, and mammals.
  • Pest control: Of wood-boring insects, including carpenter ants and termites.
  • Oozing sap caused by pecking feeds insects and hummingbirds.
  • The “Woodpecker Evolution 2” is a drill that injects insecticide.
  • Entertainment: The zany Woody Woodpecker. How many of his cartoon friends — from Chilly Willy to Andy Panda — are also endangered species?

Extinction threats and conservation efforts

  • Pileated and other woodpecker species remain at risk where old-growth and virgin forests are being clear-cut and supplanted by trees that are too small for nest cavities, too close together for successful rearing of young, or overgrown by brush.
  • In 2005, the first possible sightings of the ivory-billed woodpecker in 60 years (in an Arkansas swamp) generated both controversy and clamorous optimism about the adaptability of woodpeckers to survive in habitats that are carefully protected.

 

Ladybird Beetles – Coccinella septempunctata

Ladybird Beetles – Coccinella septempunctata

Ladybird Beetles

Coccinella septempunctata

Evolutionary history

  • The charming polka-dotted insects known as lady bugs are actually beetles.
  • The first beetles evolved in the Permian period approximately 265 million years ago.
  • Beetles are the most diverse group of organisms on Earth; more than 350,000 species have been identified, representing 25 percent of animals known to exist today!
  • The astonishing diversity of beetle species is matched by their astounding adaptability to nearly every habitat and feeding style imaginable, earning “The Age of Beetles” as a moniker for our modern world.
  • Nearly all beetles are benign: most do not bite, are not poisonous, and do not transmit diseases.

Ecological services and inspirations

  • Food for many other animals, including fish and amphibians.
  • Waste decomposition and disposal, nutrient recycling (burial beetles eat and raise their offspring in animal carcasses), and soil formation (dung beetles feed on, reproduce in, and move animal feces; stag beetles feeding on dead wood release nutrients that improve soil quality).
  • Pest control of parasites in mammal fur and bird nests.
  • Agricultural benefits: Crop pollination and voracious biopredation on pests like aphids and slugs.
  • Human culture: Bug collecting; scarab beetles are religious symbols in ancient Egyptian hieroglyphs; iridescent, brightly colored beetle carapaces are used by traditional societies and in decorative art

Extinction threats and conservation efforts

  • Pileated and other woodpecker species remain at risk where old-growth and virgin forests are being clear-cut and supplanted by trees that are too small for nest cavities, too close together for successful rearing of young, or overgrown by brush.
  • In 2005, the first possible sightings of the ivory-billed woodpecker in 60 years (in an Arkansas swamp) generated both controversy and clamorous optimism about the adaptability of woodpeckers to survive in habitats that are carefully protected.

 

Bumblebee – Bombus hortorum

Bumblebee – Bombus hortorum

Bumblebee

Bombus hortorum

Evolutionary history

  • Like ants, wasps, and other bees, the vibrant tiger-striped hairy bumblebee is a “membrane winged” hymenopteran, which are the only stinging insects.
  • Of the 25,000 known bee species, 300 are bumblebees.
  • Bees have a poor fossil record but date back about 100 million years to the Cretaceous appearance of flowering plants.
  • Unlike honeybees, their close evolutionary kin, bumblebees have simple foraging behaviors (no elaborate “dance” to signal a food source’s location). Overseen by a single queen, they abandon their nests each year.
  • Although painful, the sting of these social herbivores is an adaptation for protecting young from perceived threats to the nest, not aggression or predation.

Ecological services and inspirations

  • Agricultural benefits: Pollinators of important fruit, flower, and vegetable crops and of many wild, flowering plants.
  • Food and economic source: Crop pollinators; honey, mead, pollen, royal jelly, wax; the hot trend of beekeeping/bee farm ecotourism.
  • Medical benefits and insights: Pollen and bee sting treatments for rheumatism; honey has antibiotic properties; human immune cells cluster and communicate like bees.
  • Symbology and models: Egyptian hieroglyphics, Chinese script, currency and ceremonial emblems, religion (churches or temples denoted by a beehive); “Bumblebee Economics,” hexagons in architecture and décor; WWII “Bumblebee Project.”
  • Idioms, names: Busy as a bee, Muhammad Ali’s famous quote “Float like a butterfly, sting like a bee,” Stinger and Bee’s Kiss cocktails. or temples denoted by a beehive); “Bumblebee Economics,” hexagons in architecture and décor; WWII “Bumblebee Project.”
  • Music: Rimsky-Korsakov’s “The Flight of the Bumblebee.”

Extinction threats and conservation efforts

  • Many bee populations are at risk because of introduced competitor, predatory, or parasitic “alien” species (African “killer” bees); pollution and insecticide use; and changes in food-plant availability caused by climate change and rapid urbanization.
  • Conversations about protecting bees’ natural habitats and eradicating invasive bee species are in the beginning stages.

 

Crocodilians – Alligator mississippiensis

Crocodilians – Alligator mississippiensis

Crocodilians

Alligator mississippiensis

Evolutionary history

  • Crocodilians (like the one shown here enjoying an exotic stroll), which include crocodiles, alligators, caimans, and gharials, are differentiated primarily on the basis of jaw shape, tooth placement, and behavior.
  • Fossils from 240 million years ago reveal that these once terrestrial and now semi-aquatic reptiles shared a common ancestor with dinosaurs, their evolutionary cousins.
  • A testament to their resiliency is their ability to have co-existed with (even preyed upon) dinosaurs and to survive the extinction event that ended dinosaur rule in the late Mesozoic.

Ecological services and inspirations

  • Tourism dollars both in wild areas and at zooparks and farms benefit local and regional economies.
  • Cultural symbol: The Chinese dragon’s form is said to have been inspired by the crocodile.
  • Research that involved putting crocodiles through their paces on treadmills determined how a special respiratory physiology enabled their extinct dinosaur relatives to have been more active than previously thought.

Extinction threats and conservation efforts

  • Pileated and other woodpecker species remain at risk where old-growth and virgin forests are being clear-cut and supplanted by trees that are too small for nest cavities, too close together for successful rearing of young, or overgrown by brush.
  • In 2005, the first possible sightings of the ivory-billed woodpecker in 60 years (in an Arkansas swamp) generated both controversy and clamorous optimism about the adaptability of woodpeckers to survive in habitats that are carefully protected.

 

Land Slug – Arion distinctus

Land Slug – Arion distinctus

Land Slug

Arion distinctus

Evolutionary history

  • The largest slug, up to 12″ in length, inhabits Europe.
  • As mainly soft-bodied animals living in terrestrial habitats, the slug’s fossil record is poor, but dates back possibly 300 million years.
  • These hermaphrodites have two sets of tentacles, one for sensing light, the other for detecting chemical aromas.
  • A ribbony tooth comprising more than 20,000 elements enables consumption of plants of all kinds, roots, and fungi.
  • Some species are carnivorous.

Ecological services and inspirations

  • Food for amphibians, reptiles, birds, and mammals.
  • Although a few species can wreak havoc in garden plots, slugs are indispensable “composters,” foraging on leaf litter, decaying flesh and vegetable matter, and feces.
  • Mascot: The Banana Slug gained national cinematic attention when John Travolta donned a University of California–Santa Cruz T-shirt in Pulp Fiction.
  • Names: Banana Slug String Band (musical environmental educators), the “Cubist slug” (a British tank).
  • Asteroid dwellers and Jabba the Hut of Star Wars series fame.
  • Events: Oregon’s annual SLUG (Society for Legitimization of Ubiquitous Gastropod) Queen Fest; International Slug Festival photography contest.

Extinction threats and conservation efforts

  • Slug species are endangered because of shrinking woodlands and forests, which raises concerns about environmental decline due to loss of slugs’ ecological benefits.
  • In your garden, deter slugs naturally by erecting slug barricades of pine needles, wood ash, or copper tape around plants.

 

Giant Clam – Tridacna gigas

Giant Clam – Tridacna gigas

Giant Clam

Tridacna gigas

Evolutionary history

  • The world’s largest bivalved mollusk. Tridacna’s lineage extends back 30 million years to the mid-Tertiary.
  • Seven species survive today, in reefs of the South Pacific, Indian Ocean, and Red Sea.
  • Tridacna can live 100 years, growing to more than 4′ in length and weighing more than 500 pounds — too large to be a good aquarium pet!
  • Flesh can be brilliant shades of cobalt, turquoise, or magenta.
  • Reports that these so-called “killer clams” can trap a diver’s arm or foot inside its shell are unsubstantiated.

Ecological services and inspirations

  • Aquaculture for human consumption, salt-water aquaria, and shell collectors.
  • Provides a substrate for many other reef species, such as corals, anemones, sponges, worms, and algae.
  • Environmental biosensor: Tissues record levels of trace metal pollution in reef habitats.
  • Shells are used for engravings, baptismal fonts, bird baths, water carriers, basins, flowerpots, mallets, hoes, scrapers, and jewelry.
  • In the cultured pearl industry, a shell fragment is inserted inside an oyster to serve as the nucleus.

Extinction threats and conservation efforts

  • The International Union for Conservation of Nature identifies some species as vulnerable to extinction because of marine pollution, reef degradation, and overharvesting.
  • Community-level aqua-farming ventures hope to establish sustainable populations while improving the livelihood of indigenous coastal peoples.

 

Elephant – Loxodonta africana

Elephant – Loxodonta africana

Elephant

Loxodonta africana

Evolutionary history

  • The largest land-dwelling animals on Earth, elephants can weigh up to 5 tons.
  • Most of the 300-plus species of proboscidean mammals identified as fossils from as early as the Tertiary 50 million years ago are extinct.
  • Each day, these nearly hairless mammals (like the African savanna elephant pictured here) feed up to 18 hours — taking in as much as 600 pounds of vegetation and 40 gallons of water — and excreting up to 400 pounds of dung.
  • Oversized ears help them thermoregulate, signal to each other, and pick up low-frequency sounds, enabling long-distance communication across a 50- to 100-square-kilometer range.
  • Related females in matriarchal herds give extended care to the young, injured, and sick, and to bones in elephant “graveyards.”

Ecological services and inspirations

  • While foraging, elephants “bulldoze” the landscape, creating waterholes and firebreaks and enriching the soil with their prolific manure for a diversity of species that feed in their wake.
  • This “flagship” species draws vital tourist dollars to developing countries.
  • In the Hindu faith, Ganesh (the elephant-headed god) symbolizes power, intelligence, and luck.
  • Art, literature: Paleolithic mammoth cave paintings; children’s favorites Dumbo, Babar, and Horton.
  • Military history: War elephants crossed the Alps with Hannibal in 218 BC, used in battle to fight and terrorize the enemy.

Extinction threats and conservation efforts

  • Only three species remain — the savanna and forest elephants in Africa, and the Asian elephant, found in localized populations across southeast Asia.
  • Poaching for ivory exterminated 50 percent of elephant populations across Africa in the 1980s.
  • Although fewer than 700,000 survive in Africa today, elephants continue to be slaughtered for their ivory (international law allows for restricted trade), “bush meat,” or to protect crops from being eaten or trampled in areas where human populations have expanded into elephant habitat.

 

Turtle – Trachemys scripta elegans

Turtle – Trachemys scripta elegans

Turtle

Trachemys scripta elegans

Evolutionary history

  • The fossil record reveals that the first turtles lived on land about 200 million years ago in the Age of Dinosaurs.
  • They diversified into tortoises, fresh-water turtles like the photogenic red-eared slider specimen pictured here, and sea turtles; more than 300 species exist today.
  • These reptiles grow slowly; some species take as many as 15 to 20 years to reach sexual maturity.

Ecological services and inspirations

  • Food for human consumption — eggs and meat — but concerns arise from unsustainable harvests; prey for birds, raccoons, foxes.
  • Keystone species: Helps maintain ecosystem health by feeding on plants and aquatic prey.
  • Ecotourism: Tortoises draw many to the Galapagos and Seychelles.
  • Literature and entertainment: We all know Aesop’s The Tortoise and the Hare, Suess’s Yertle the Turtle, and the Teenage Mutant Ninja Turtles, but who was Churchy LeFemme?
  • Human culture: Pets; a figure in native creation myths; religious symbol of longevity, strength, endurance, and peacefulness.

Extinction threats and conservation efforts

  • More than two-thirds of tortoise and freshwater turtle species are threatened with extinction because of unregulated harvests, illegal poaching, and habitat degradation from pollution, river dredging, and wetland alteration; water diversion through dams, and reservoirs; and disruption of breeding and nesting sites.
  • Habitat protection, captive breeding programs, and more research on the ecology of turtle populations around the world are crucial for saving many of these species from extinction.
  • High rates of juvenile mortality mandates special strategies for their conservation.

 

Chambered Nautilus – Nautilus pompilius

Chambered Nautilus – Nautilus pompilius

Chambered Nautilus

Nautilus pompilius

Evolutionary history

  • Prized by shell collectors as one of the most beautiful invertebrates on Earth, this unusual cephalopod mollusk is distantly related to the octopus.
  • Of more than 10,000 fossilized species found in rocks as old as the Late Cambrian 500 million years ago, only 5 or 6 survive today, in the Indian and western Pacific Oceans.
  • Oriented as shown here, the nautilus swims backward (away from where it is looking) by squeezing a stream of water out of its shell. By altering the proportion of seawater and gas in each chamber of its shell, it rises and descends like a submarine.
  • Much remains to be learned; this rare, shy, nocturnal inhabitant of moderately deep seas (between 300′ and 600′) is difficult to study.

Ecological services and inspirations

  • Food: For sharks, other marine predators, and indigenous coastal people.
  • Decorative arts: Aquarium and shell curio trade; Chinese “pagoda” shells; Swedish Olandsspikar; engraved commemorative scenes.
  • Literature: Oliver Wendell Holmes’s poem, “The Chambered Nautilus.”
  • Mathematical principle: The shell is an example
    of logarithmic spiraling and the golden triangle.
  • Product/brand name: A fitness company; the world’s first nuclear-powered submarine; a loudspeaker; a compact motorcycle horn; a fly-fishing reel; a gravitational wave detector; a record album; pinot gris wine; software filing system; secure invisible holography system; and many organizations, including a maritime union, therapeutic drug firm, financial trust company, and a global securities institute.

Extinction threats and conservation efforts

  • A decline in nautilus shells suggests they are being overharvested for the aquarium and shell curio trade.
  • Although long-lived for invertebrates (up to 10 or 20 years), they are especially vulnerable because they take several years to reach sexual maturity, females produce only a few eggs each year, and many inhabit threatened coral reefs.

 

FSEM 136: The Sixth Extinction

Constance M. Soja, Professor of Geology TTh 9:55-11:10, 344 Ho Science Center

The fossil record — Earth’s “ticker tape” of past life — reveals that our planet has experienced five cataclysmic events, or mass extinctions. Each mass extinction profoundly influenced Earth’s history by redirecting the course of evolution. As detectives attempting to solve the world’s greatest murder mysteries, students examine when each of these catastrophes occurred, what caused ecosystem collapse, why and where species died, and who survived to begin the evolutionary repair of life.

In the final part of the course, students investigate the severity of the Sixth Extinction, which many scientists believe is already underway as a result of Earth’s most powerful geologic and evolutionary force, Homo sapiens. We also debate modern conservation practices dedicated to preserving biological diversity during a time of rapid global change.

Students participate in a “fossilization experiment” and in collaborative learning exercises that involve library or web-based research, group presentations, discussions, and debates. These exercises sharpen critical-thinking skills and strengthen writing proficiency.

Evaluation is based on writing assignments, oral presentations, a midterm, and a final research paper. Students who successfully complete this seminar satisfy their Scientific Perspectives core requirement.


 

Editor’s note: A number of Colgate professors are conducting scholarship — and involving their students — in various aspects of humans’ impact on the Earth. This article is the first in what we intend to be an occasional series featuring projects that approach the subject in creative, and sometimes counterintuitive, ways.

 


 

Ads reproduced with permission: Rechargeable Battery Recycling Corporation (woodpecker), Everyware Global/Oneida (ladybug), Wild Card/Jordan’s (bumblebee), Pernod Ricard/Kahlua (crocodilians), CropLife Canada (slug), Gibson Exclusive Furniture (clam), Skyy/Campari (elephant), Pentax-Ricoh Imaging USA (turtle), Jay Strongwater (nautilus)