De-extinction: Should we resurrect extinct species?

De-extinction, the process of reviving extinct species through biotechnology, has moved from science fiction to technical reality. By 2025, projects like those for the woolly mammoth and the thylacine are progressing rapidly, sparking intense debate among scientists, ecologists, and philosophers about whether, and under what conditions, we should bring back species that nature (and often humanity) eliminated.

What is De-extinction and How Does It Work?

Key Techniques in 2025

1. Cloning with Ancient DNA:
   • Extraction of genetic material from preserved remains
   • Implantation into eggs of living related species
   • Example: Pyrenean ibex (Capra pyrenaica pyrenaica), briefly cloned in 2003
2. CRISPR-Cas9 Gene Editing:
   • Modification of the genome of extant species to recreate extinct phenotypes
   • Flagship Project: Woolly mammoth → Asian elephant with cold-resistance genes
3. Reverse Selection:
   • Selective breeding to recover ancestral traits
   • Example: Project Taurus to recreate the aurochs
4. Whole Genome Synthesis:
   • Digital reconstruction and chemical synthesis of complete genomes
   • Still under development, but promises greater accuracy

Most Advanced Current Projects

1. Woolly Mammoth (Mammuthus primigenius)

• Led by: Colossal Biosciences (USA)
• Status: Editing of 60 key genes in Asian elephant completed
• Challenges: Gestation (22 months), social behavior, suitable ecosystem
• Estimated cost: $75 million

2. Thylacine or Tasmanian Tiger (Thylacinus cynocephalus)

• Led by: University of Melbourne + Colossal
• Progress: Whole genome sequencing from museum specimens
• Surrogate species: Fat-tailed marsupial mouse (genetically similar)

3. Passenger Pigeon (Ectopistes migratorius)

• Led by: Revive & Restore (USA)
• Achievement: 200 genes edited in passenger pigeon
• Advantage: Short reproductive cycle (allows for rapid iteration)

4. Australian Gastrotracheal Frog (Rheobatrachus silus)

• Unique feature: Unique incubation Eggs in stomach
• Breakthrough: Cloning of cells preserved in 1970
• Importance: Recovery of a unique evolutionary adaptation

Arguments in Favor: Why We Should

1. Ecological Restoration

• Key species: Recover lost ecosystem functions
• Example: Mammoths in the tundra could:
  • Compact snow, reducing the thermal insulation of the permafrost
  • Stimulate the growth of grasslands that reflect more sunlight
  • Impact: Potential mitigation of Arctic climate change

2. Intergenerational Justice

• Moral responsibility: Correct extinctions caused by humans
• Priority candidate species:
  • Dodo (Raphus cucullatus): Hunted to extinction in 1662
  • Giant moa: Eliminated by Māori in New Zealand

3. Scientific Advancement

• Derived technologies:
  • Conservation of endangered species through seed banks Genetic
  • Disease resistance in livestock and crops
  • Human regenerative medicine

4. Environmental Awareness

• “Flagship species”: Attracting public attention and funding
• Living education: Tangible symbols of the fragility of biodiversity

Arguments Against: Risks and Criticisms

1. Misplaced Priorities

• Opportunity cost: The $75 million for the mammoth could protect 300 current endangered species
• Figures:
  • Conventional conservation: $1,000-$50,000/year per species
  • De-extinction: $500,000-$5 million per individual created

2. Ecological Challenges

• “Laboratory creatures”: Without transmitted culture or behavioral adaptations
• Example: Mammoth without a herd to teach migratory routes
• Unpredictable ecosystem effects: Reintroduced species can become invasive

3. Well-being Animal

• Potential suffering: Genetically modified animals with health problems
• Isolation: The first of their kind in thousands of years
• Lack of natural habitat: Many original ecosystems have disappeared

4. False Solution

• “Moral permission”: Believing we can fix what we break
• Disincentive to conservation: “If they go extinct, we’ll just bring them back”
• Paradox: We need intact habitats to release resurrected species

Positions of the Scientific Community in 2025

In Favor with Conditions (60% according to Nature survey)

• Proposed Criteria:
  1. Human Cause: Only species driven to extinction by direct human activity
  2. Available Habitat: Ecosystems capable of supporting them
  3. Ecological Function: They must fulfill a specific role in restoration
  4. Mature Technology: Minimize suffering during the process

Neutral/Skeptical (30%)

• Position: Basic research yes, practical application with extreme caution
• Proposal: Genetic cryobanks as an “insurance policy”

Openly Opposed (10%)

• Main Argument: Money better invested in protecting existing biodiversity
• Representative Quote: “We can’t save what we have, and we want to bring in more?”

Emerging Regulatory Framework

International Guidelines

• IUCN (2024): “Guidance for Ethical and Ecological Considerations”
• EU Biosafety: Protocols for Historically Modified Organisms
• Convention on Biological Diversity: Amendment on “Organisms of Past Extinction”

Proposed Categories for Resurrected Species

1. Ex situ conservation: Only in controlled facilities
2. Experimental reintroduction: Large-scale fenced areas
3. Full release: Only if a net ecosystem benefit is demonstrated

Alternatives: Preventive Approaches

Living Genomic Banks

• Frozen Ark Project: Stores DNA from 48,000 threatened species
• Lunar Archive: Backups on the Moon (2028 project)

Conservation Corridors

• 30×30 Initiative: Protect 30% of land and sea areas for 2030
• Connectivity: Enabling natural migrations and adaptation

Technology for Living Species

• CRISPR for conservation: Disease resistance in amphibians
• Emergency cloning: For species with fewer than 10 individuals

The Future: Probable Scenarios

2025-2030: First Generation

• Outcomes: Multiple individuals of “easy” species (amphibians, birds)
• Location: Primarily zoos and fenced reserves
• Impact: Mostly educational and research-based

2030-2040: Limited Reintroductions

• Candidates: Species with a clear ecological role and available habitat
• Example: Passenger pigeon in managed forests
• Condition: Intensive monitoring with satellite and drone technologies

Post-2040: Ecosystem Engineering

• Vision: “Pleistocene Parks” with multiple resurrected species
• Locations: Siberia, Alaska, islands with biosecurity controls
• Objective: Climate mitigation + ecological restoration

“The question is not whether we can revive species, but whether we should. And if we do, what version of the past are we trying to recreate, and for whose benefit?” — Dr. Susana Martínez, bioethicist at the European Research Council.