The extinction of animal species is an unfortunate but common occurrence throughout Earth’s history. However, in rare cases, species thought to be extinct have later been rediscovered. This phenomenon, known as the Lazarus effect or taxon resurrection, involves the reappearance of a species after a period of apparent absence or extinction. Some notable examples of animals that have seemingly evolved back into existence include the coelacanth, the Lord Howe Island stick insect, and the Myanmar snub-nosed monkey.
What causes the Lazarus effect?
There are a few key factors that can lead to the Lazarus effect:
- Incorrect declaration of extinction – In some cases, animals may be declared extinct when in fact small populations continue to survive undetected.
- Rediscovery of surviving populations – Small populations that persist after apparent extinction may eventually be rediscovered by scientists and conservationists.
- Recolonization – Animals from nearby regions may recolonize an area where a species was declared extinct and reestablish a breeding population.
- Resilience to change – Some species are able to survive dramatic changes to their environments and recover from near-extinction.
Mistaken extinction declarations, isolated surviving populations, and species’ resilience to habitat loss and change can all play a role in Lazarus taxon events when species thought extinct are found again.
Famous examples of the Lazarus effect
The coelacanth
The coelacanth is a prehistoric-looking lobe-finned fish that was thought to have gone extinct along with the dinosaurs approximately 66 million years ago. That changed in 1938 when a living specimen was caught off the coast of South Africa. Coelacanths had in fact survived relatively unchanged for millions of years in small numbers in the deep ocean.
The Lord Howe Island stick insect
The Lord Howe Island stick insect was endemic to Lord Howe Island in the Tasman Sea. After the introduction of black rats to the island in 1918, the insect was assumed wiped out by the rats and declared extinct in 1960. But in 2001, a group of rock climbers rediscovered a surviving population on a steep volcanic spire just offshore from Lord Howe Island. This small population of a few hundred insects was used to start a captive breeding program, allowing the Lord Howe Island stick insect to eventually be reintroduced to its native island habitat.
The Myanmar snub-nosed monkey
The Burmese snub-nosed monkey had only been described from a few preserved specimens collected in Myanmar over a hundred years ago. Scientists thought the species was likely extinct due to hunting and habitat loss. That changed when an expedition photographed and filmed live individuals in 2010 in remote northern Myanmar. It marked the monkey’s first confirmed sighting in over 60 years. Further expeditions have found sizable populations of the monkeys in Myanmar and China, suggesting it persists despite past threats.
Why do Lazarus taxa go extinct in the first place?
There are several key threats that can drive species from abundant to locally or globally extinct:
- Habitat destruction – Deforestation, urbanization, agriculture and other human activities can destroy or fragment essential habitat for species survival.
- Overexploitation – Overhunting, overfishing and overcollection drive many species toward extinction.
- Invasive species – Competition from or predation by invasive species impacts native wildlife.
- Climate change – Changing environmental conditions can make areas uninhabitable for species adapted to certain habitats.
- Disease – Emerging diseases and epidemics may decimate populations.
- Natural disasters – Catastrophic events like volcanic eruptions can rapidly wipe out populations and species.
In many Lazarus taxon cases, species decline due to combinations of these threats, but go unnoticed or mistakenly declared extinct before final disappearance. Isolated populations manage to hang on undetected.
Why do some species remain resilient to extinction?
There are certain traits and circumstances that make some species more resistant than others to extinction threats:
- Generalist species – Generalists capable of utilizing a variety of habitats and food sources are more resilient than specialists.
- Large habitat range – Species occupying large geographic ranges are less vulnerable than endemic species confined to small areas.
- High genetic diversity – Genetically diverse populations are better able to adapt to changes.
- High reproductive rate – Prolific breeders recover from population crashes more easily.
- Low human value – Species not valued for food, medicine or sport are subject to lower exploitation.
- Inaccessible habitat – Isolated or hard-to-reach refuges shield some populations from disturbances affecting wider areas.
These natural buffers help some Lazarus taxon species avoid extinction and make unlikely recoveries from near-extirpation possible.
Can extinct species ever be revived?
While the Lazarus effect shows some species can avoid extinction against the odds, once a species is conclusively gone for good, any revival would require advanced technological intervention. Some ways extinct species could potentially be resurrected include:
- Cloning – If tissue samples are adequately preserved, cloning cells and embryos to create individuals is theoretically possible, though challenging.
- Genetic engineering – Using genome editing tools to insert extinct species’ DNA into living related species’ genomes could regenerate lost species.
- Breeding surrogates – Selectively breeding living species to produce animals that resemble extinct lineages could generate proxies for extinct species.
While such techniques are being investigated, currently no extinct species have been successfully revived. Actual de-extinction may prove difficult, expensive, and limited in ability to reproduce complex extinct organisms.
Ethical considerations in reviving extinct species
While technologically reviving extinct species is becoming a possibility, it also raises many ethical questions, including:
- Would revived species have sufficient habitat and conservation support to sustain populations?
- What ecological impacts could introduced extinct species have on existing ecosystems?
- How can we ensure revived populations remain genetically healthy?
- What conservation value would extinct species reestablishment provide compared to conserving still-endangered species?
- Could commercial exploitation of once extinct species be controlled?
Addressing these ethical questions will be key to ensuring any de-extinction efforts provide true conservation value and carefully consider unintended consequences for existing species and ecosystems.
Preventing future extinctions
Ultimately, putting resources into conserving still-existing imperiled species may prevent more biodiversity loss than attempting to revive extinct species after the fact. Some ways we can promote conservation and avoid future preventable extinctions include:
- Expanding protected areas and habitat connectivity
- Controlling invasive species and diseases
- Sustainably managing harvest and trade of wild species
- Reducing resource consumption and greenhouse gas emissions
- Protecting genetic diversity within wild populations
- Monitoring and safeguarding small and fragmented populations
Targeted conservation programs for the species at highest risk today could help avoid imminent extinctions and preserve biodiversity for future generations. The Lazarus effect shows that we may sometimes get lucky with species rebounding from presumed extinction. However, we cannot rely on chance and instead must take deliberate action to protect species before it is too late.
Key Lazarus taxon case studies
Here are some of the most remarkable examples of Lazarus taxa that were rediscovered after long periods of apparent absence or extinction:
| Species | Rediscovery year | Years thought extinct |
|---|---|---|
| Coelacanth | 1938 | 66 million |
| Wollemi pine | 1994 | 2 million |
| La Palma giant lizard | 2007 | 500 |
| New Zealand storm petrel | 2003 | 150 |
| Cahow (Bermuda petrel) | 1951 | 300 |
| Gracilidris (bird genus) | 2006 | 73 |
Each Lazarus taxon has a remarkable story of survival against the odds before eventual rediscovery by scientists. These striking examples demonstrate that extinction is not always forever. With enough resilience, luck and searching by dedicated researchers, some species can endure undetected long after they are thought to be gone and be found again.
Conclusion
The Lazarus effect provides hope that species and biodiversity may yet persist even through dramatic environmental changes. But its rare occurrences underline why proactive conservation before extinction is so essential. With expanding human activity worldwide, more and more species require urgent safeguarding to avoid preventable extinctions in the first place. Going forward, balancing revival efforts with habitat protection and restoration will be key to preserving species both old and new for the future.
