The dodo -- an extinct bird made famous in traveling exhibitions and works of fiction -- may be ready for a comeback. In early July 2007, scientists working on the island of Mauritius, east of Madagascar off of the coast of Africa, announced the discovery of the best preserved dodo skeleton ever found. It appears complete and is one of only two of the extinct bird that's been unearthed. The find, which was kept secret for several weeks while the site was examined and the skeleton collected, may provide valuable DNA samples.
The new dodo skeleton is particularly exciting because it was found in a cave, which helped to preserve the specimen and, scientists hope, its DNA. Many dodo bones have been discovered in Mauritius' swamps, but the swamp environment has a corrosive effect on the bones. The only other dodo DNA came from a 15th-century skeleton brought to Britain from Mauritius. That sample allowed scientists to determine the bird's relationship with other birds. The study revealed that dodos are related to many types of pigeons and doves. The new skeleton may reveal even more information about the dodo, including a more complete version of the animal's genetic code. This find raises the question: Could scientists resurrect the dodo bird?
First, let's get to know the dodo, an animal that continues to live quite a life in popular culture and our lexicon, even after its extinction more than 300 years ago. Dutch and Portuguese explorers discovered dodos in 1598, and the bird went extinct about 80 years later. Living in the forests of Mauritius, dodos grew to about one meter (three feet, three inches) in length and weighed up to 20 kilograms (44 pounds) [Source: Peter Maas]. Their feathers varied from white to shades of gray and black, and they had a large beak that was almost swollen in appearance. Recent analyses show that, contrary to common belief, dodos probably weren't excessively fat, round birds. Instead they were thinner and more proportionate to other birds, though their short legs may have made their bodies seem larger than they were.
Beth Shapiro, a scientist at Oxford University, told National Geographic that "dodos were essentially fat pigeons" [Source: National Geographic]. But many explorers' accounts of the birds as stupid or clumsy are colored by the fact that dodos had no natural predators on Mauritius. Because they lived without fear of attack, dodos had no reason to fear people and sometimes approached them. Eating lots of low-lying food -- dodos had an omnivorous diet of fish, seeds and fruit -- made them plump and also removed the evolutionary imperative to fly. Over time, dodos' wings became shortened and they lost the ability to fly. The lack of flight combined with other strange actions, such as eating small rocks (which scientists now believe aided in digestion), contributed to dodos' appearance as stupid, lazy birds. Instead, they hunted fish, had a strong bite and kept the same partner throughout life, with both animals helping to raise the couple's young.
The dodo went extinct because of one reason: humans. Portuguese and Dutch explorers introduced dogs, rats, pigs, monkeys, cats and other animals to Mauritius. These animals ate the birds' eggs, which were laid on the ground. Humans hunted the dodos for food, even though the meat reportedly wasn't very flavorful, and took many dodos abroad to be displayed in exhibits. Eventually, the bird and its eggs were hunted to extinction.
On the next page, we'll look at whether the dodo can be brought back to life -- and if it's ethical to do so.
Resurrecting the Dodo and Other Extinct Creatures
Though some experts contend that it will never be possible, a great debate is underway in science about whether it's ethical to bring an extinct species back to life. Some animals are driven to extinction by human action, but others simply can't survive in their natural habitat or because of a major change in climate. Earth has gone through several mass extinctions, and bringing back many of these creatures could throw the world's ecosystem into chaos.
There's the question of where these creatures would go, especially since many extinct creatures would have no natural predators, except for humans. Would putting a saber-tooth tiger in the Siberian tundra disrupt the local food chain (in addition to terrorizing locals)? The alternative is keeping recreated species in a "Jurassic Park"-like zoo or nature preserve, which is exactly what a group of Japanese scientists proposed in 2005.
In July 2007, a very well preserved woolly mammoth carcass was discovered in Siberia, reinvigorating debate about trying to resurrect the species. Some scientists contend that resurrecting extinct species may be easier with frozen animals. Sperm from mice frozen for 15 years have been used to inseminate living mice. The contention is that a female elephant could be inseminated with recovered mammoth sperm to create an elephant-mammoth hybrid. But dodos only lived in the warm climate of Mauritius and the surrounding islands -- the likelihood of finding a frozen one is slim to say the least -- so scientists would have to turn to other means to bring them back to life.
Another possibility proposed for mammoths is to remove DNA from an elephant egg and fuse it with the cell of a mammoth. That would create a creature that's 100 percent mammoth. A similar technique could conceivably be tried with a dodo, perhaps using a Nicobar pigeon, the dodo's closest non-extinct relative. But the cloned embryo would still have to be implanted into a living creature that can carry it to term (or until the egg is laid, in the case of the pigeon).
And yet another proposed method would be to use DNA from an extinct animal, like a dodo or mammoth, as a model. A living relative would then be genetically engineered to give birth to offspring that are essentially the model animal.
Extracting and decoding the DNA is the fundamental challenge. Cells break down over time, even in well preserved or frozen specimens. Gaps in DNA mean that piecing together the full genetic map of a creature may be impossible. Gaps can lead to birth defects or unviable offspring. Some scientists also believe that sperm frozen for tens, or even hundreds, of thousands of years won't be usable. Yet things that seemed impossible a decade or two ago are now happening thanks to the rapid pace of genetics research. Scientists have produced full genetic maps of several living species, including humans and dogs, and have even recreated the 1918 influenza virus that killed millions.
However, even if better DNA samples, improved genome-decoding techniques and more knowledge of cloning eventually make it possible, do we want revived dodos or woolly mammoths lumbering around? Proponents of the process contend that much could be learned from bringing back these animals, while critics say that the process could quickly get out of control. For example, researchers believe that it's possible to fully map the Neanderthal genome, which should teach us more about the relationship between modern humans and our ancient forebears. But is it ethical and wise to take the next great leap by cloning a Neanderthal? Perhaps they learned nothing from the movie "Encino Man."
For more information about dodos, cloning, animal extinction and related topics, please check out the links on the next page.
Related HowStuffWorks Articles
More Great Links
- Inman, Mason. "Mammoths to Return? DNA Advances Spur Resurrection Debate." National Geographic News. June 25, 2007. http://news.nationalgeographic.com/news/2007/06/070625-dna-resurrection.html
- Lovgren, Stefan. "Woolly Mammoth Resurrection, "Jurassic Park" Planned." National Geographic News. April 8, 2005. http://news.nationalgeographic.com/news/2005/04/0408_050408_woollymammoth.html
- Maas, Peter. "Dodo." The Extinction Website. Jan. 29, 2007. http://www.petermaas.nl/extinct/speciesinfo/dodobird.htm
- Mayell, Hillary. "Extinct Dodo Related to Pigeons, DNA Shows." National Geographic News. Feb. 28, 2002. http://news.nationalgeographic.com/news/2002/02/0227_0228_dodo.html
- Ravilious, Kate. "Dodo Skeleton Found on Island, May Yield Extinct Bird's DNA." National Geographic News. July 3, 2007. http://news.nationalgeographic.com/news/2007/07/070703-dodo.html
- Rincon, Paul. "Baby mammoth discovered." BBC News. July 10, 2007. http://news.bbc.co.uk/2/hi/science/nature/6284214.stm
- Schmid, Randolph E. "Japanese Researcher Ponders Reviving Woolly Mammoth." The Associated Press. Live Science. Aug. 14, 2006. http://www.livescience.com/animals/ap_060814_woolly_mammoth.html
- Schmid, Randolph E. "Study: Neanderthal Genome Map Possible." The Associated Press. Discovery News. June 26, 2007. http://dsc.discovery.com/news/2007/06/26/neanderthal_arc.html?category=archaeology&guid=20070626100000&dcitc=w19-502-ak-0000
- "Alice in Wonderland dodos." The Dodo Blog. June 17, 2006. http://dodo.bibi.org/alice-in-wonderland-dodos/