SCIENCE

A new study indicates a small breeding population may have doomed the last woolly mammoths, a theory that could change how we think about conservation efforts today. (Christian Science Monitor)

Should we resurrect the woollies? How would we maintain the genetic diversity that is crucial to healthy populations?

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit, including today’s MapMaker Interactive map.

Discussion Ideas

• The new study compares two wooly mammoth genomes, representing populations separated by 40,000 years and very different ecosystems. What different ecological niches did the two populations fill?
  • The older individual died about 45,000 years ago. It was part of a mainland mammoth population, in what is now the Oimyakon district of northeastern Siberia, Russia. These mammoths were well-adapted to life during our most recent glacial period—the Ice Age.
    • A thick, rough coat of fur gave the mammoths their name (woolly) and kept them warm.
    • Their small ears and tails reduced the chances of frostbite. (Compare mammoth ears to those of their Indian elephant cousins that live in the tropics.)
    • A mammoth’s big, beautiful tusks and molars were ideally suited for its diet of grasses and sedges of the cold, dry steppe that nearly circled the entire Northern Hemisphere during the Ice Age. Woolly mammoths were so extensive in this big ancient biome that scientists call it “the mammoth steppe.”
    • The Oimyakon individual was part of a breeding population of about 13,000 individuals. (!)
  • The younger individual died about 4,300 years ago. It was part of the population of mammoths on what is now Wrangel Island, a remote Russian nature preserve in the Arctic Ocean.
    • The Wrangel Island individual was part of a breeding population of about 300 individuals.
    • The Wrangel Island mammoths were the last living woolly mammoths on Earth. The genome in the study dates from just a few hundred years before the species became extinct.

• What were leading factors in the extinction of the mainland population of woolly mammoths?
  • climate change. As the Ice Age ended, the “mammoth steppe” transformed from grasslands to forests, tundra, and lakes. Woolly mammoths were unable to adapt to this rapidly changing ecosystem.
  • human activity. Woolly mammoths coexisted with human populations (both modern humans and Neanderthals). These humans were pretty good at both hunting the mammoths and depicting them in art. In some areas, human survival was crucially linked to the mammoth: mammoth meat was consumed for nutrients, mammoth fur and skin were used as clothing and blankets, mammoth bones and tusks were used as tools, construction material, and decorative items.

• What were leading factors in the extinction of the Wrangel Island population of woolly mammoths?
  • Climate change contributed to the decline mammoth populations on islands as well as the American and Eurasian mainland.
  • A thousand years after all other mammoths died, the tiny population of Wrangel Island mammoths faced nothing less than a “genomic meltdown.” A lack of genetic diversity allowed “bad mutations” to flourish in the population. Scientific American sums up these bad mutations as “see-through hair and awkward sexual problems.”
    • see-through hair. The stiff, coarse fur of the woolly mammoth became transparent, soft, and shiny. “The mighty woolly mammoth became a ‘satin’ mammoth,” according to the Christian Science Monitor. Satin is not warm, and although the Ice Age was over, Wrangel Island was (and is) still a very, very cold place to be. As the New York Times says, “A herd of Wrangel mammoths in moonlight might have shimmered like ghosts, but any compromise to their insulation would have jeopardized survival.”
    • The “awkward sexual problems” may have been a feedback loop in three parts:
      • urine trouble. Wrangel Island mammoths lost major urinary proteins. These proteins are associated with mate choice and social status.
      • no sense of smell. Wrangel Island mammoths lost many of the olfactory genes that allowed them to smell, which prevented them from efficiently finding food, staying away from many rotting or toxic materials, and sniffing out a healthy mate.
      • pheromone receptors. Wrangel Island mammoths lost receptors in their vomeronasal organ, which is mainly used to detect pheromones. Pheromones are chemicals that carry information and trigger social responses in members of the same species. Pheromones can transmit information about fertility, food, and general alarm.

• The study on Wrangel Island woolly mammoths has “very important implications for conservation biology” today. Why?
  • The study suggests “the existence of a population point of no return, after which a species may never recover, no matter what careful protections are afforded to the endangered individuals.”
  • The study may encourage conservationists to focus on vulnerable species with relatively healthy genetic populations, before they become critically endangered and more susceptible to “genomic meltdown” and bad mutations.

• What endangered species are in danger of suffering “genomic meltdowns” similar to the woolly mammoth?
  • The paper identifies Asiatic cheetahs, pandas, and mountain gorillas. The gorilla population in particular, the authors note, is similar to that of pre-extinction mammoths.
  • Here’s a longer list of critically endangered species, whose populations and ranges make them most vulnerable.

TEACHERS TOOLKIT

Christian Science Monitor: New discovery reveals mystery of the woolly mammoth

Nat Geo: Genomic Meltdown of Mammoth Proportions map

Nat Geo: Will We Bring Back Extinct Species? study guide

(extra credit!) PLoS Genetics: Excess of genomic defects in a woolly mammoth on Wrangel Island