Extinct animals that are alive represent a biological paradox, challenging the definition of a species’ disappearance. The International Union for Conservation of Nature (IUCN) declares a species “Extinct” only when there is no reasonable doubt that the last individual has died. This determination requires exhaustive surveys in all known and expected habitats over a timeframe appropriate to the organism’s life cycle. When an animal considered extinct is rediscovered, it means the initial scientific assessment, while rigorous, was incorrect. The reappearance of species illustrates that absence of evidence is not always evidence of absence, leading to two distinct concepts: genuine rediscovery and technological resurrection.
Species Thought Extinct But Found Alive
The concept of a “Lazarus Taxon” refers to species that vanish from the observational record, sometimes for decades or millions of years, only to reappear alive. This term applies to organisms mistakenly declared extinct. The most celebrated example is the Coelacanth (Latimeria), a lobe-finned fish known only through fossils dating back 400 million years and thought to have died out 66 million years ago.
In 1938, a living Coelacanth was pulled from the Indian Ocean off the coast of South Africa. Subsequent discoveries identified two extant species, the West Indian Ocean Coelacanth and the Indonesian Coelacanth, which inhabit deep-sea volcanic slopes and caves.
Similarly, the Lord Howe Island Stick Insect (Dryococelus australis), often called the “tree lobster,” was declared extinct in 1930 after rats invaded its native Australian island. A small population of these large, flightless insects was rediscovered in 2001, surviving on a single shrub on Ball’s Pyramid, a volcanic sea stack 14 miles away. Another terrestrial example is the Chacoan Peccary (Catagonus wagneri), a pig-like mammal known only from Ice Age fossils until a live specimen was found in the remote Gran Chaco region of South America in 1975. These reappearances emphasize the difficulty of confirming extinction in hard-to-access environments.
Factors Contributing to Apparent Extinction
The apparent disappearance of a species often occurs because their habitat makes them difficult to locate and monitor. Many species live in deep-sea environments, subterranean cave systems, or remote, dense tropical forests that are prohibitively difficult to survey thoroughly. These habitats can shield small populations from human observation even as their main populations decline elsewhere.
Some organisms naturally exist at very low population densities across a large geographic range, making encounters rare even when they are not endangered. Insufficient scientific surveying is another factor, as researchers may lack the funding or time to conduct comprehensive searches across a species’ entire historical range. The timing of surveys is also important, as species active only at night or during specific breeding seasons can easily be missed, leading to a premature assumption of extinction.
De-Extinction: Technological Efforts to Resurrect Species
The concept of “de-extinction” offers a second pathway to bringing back lost species through advanced biotechnology. This field aims to resurrect species whose last members have definitively died, using genetic material preserved from specimens.
Cloning
The first method is cloning, which involves taking the nucleus from a preserved cell of an extinct animal and implanting it into the egg cell of a closely related living species. This technique, called Somatic Cell Nuclear Transfer (SCNT), requires a well-preserved, intact cell nucleus. Obtaining an intact nucleus is a significant hurdle for most species that have been extinct for long periods. The Pyrenean ibex was briefly “de-extincted” in 2003 using this approach, although the clone died shortly after birth.
Genetic Engineering
A more feasible approach for older extinctions is genetic engineering, specifically using tools like CRISPR to modify the genome of a living relative. This technique is central to the project aiming to revive the Woolly Mammoth, which has a 99.6% genetic match with the Asian Elephant. Scientists are working to splice specific genes for cold-resistant traits, such as dense hair and thick fat layers, into elephant cells to create a “cold-resistant elephant” proxy. This modified embryo would then be carried to term by a surrogate Asian Elephant.
Similarly, the effort to bring back the Passenger Pigeon (Ectopistes migratorius), which went extinct in 1914, uses the Band-tailed Pigeon as a living proxy. Researchers are sequencing DNA from museum specimens to identify unique Passenger Pigeon genes and using gene editing to insert these traits into the germline cells of the living relative. The goal is to create a hybrid that is functionally and ecologically similar to the extinct species, capable of fulfilling its former role in forest ecosystems.
These de-extinction projects carry profound conservation implications. The reappearance of a Lazarus species demands immediate protection and resource allocation, proving that conservation efforts must continue even for presumed lost species. Technological de-extinction aims not just to create biological novelties, but to restore ecosystem function by reintroducing lost genetic diversity and ecological engineers, like the grazing mammoth, to their former environments.