De-Extinction of the Dire Wolf

Recently, Colossal Biosciences, U.S. based company, announced the birth of three genetically modified wolf pups, claiming them as “functional copies” of the extinct dire wolf.

• The pups, named Romulus, Remus, and Khaleesi, were born through surrogacy by dog mothers.

About the Dire Wolf

• The dire wolf (Aenocyon dirus) was a large, powerful canine that lived in North America and went extinct approximately 13,000 years ago.
• It was larger than today’s grey wolves.
• They preyed on large mammals like horses, bison, and possibly mammoths.

Technologies Used in the De-Extinction Process

• Ancient DNA Recovery: Scientists accessed dire wolf specimens, including a 13,000-year-old tooth and a 72,000-year-old skull.
  • DNA was extracted from the petrous (inner ear) bone, known for preserving genetic material well.
• Genome Sequencing: 
  • Researchers reconstructed two complete dire wolf genomes.
  • They compared these to other canids like grey wolves, coyotes, jackals, and dholes.
  • It was confirmed that grey wolves share 99.5% of their DNA with dire wolves.
• Gene Editing: Scientists introduced 20 targeted genetic edits to the grey wolf genome.
  • 14 genes were specifically modified to reproduce key dire wolf traits such as:
    • Light-colored coat
    • Coat length and pattern
    • Increased body size
    • Stronger musculature
• Embryo Implantation: Fertilized, gene-edited eggs were implanted into surrogate dog mothers which successfully led to the birth of three genetically modified wolf pups.
  

Are They Truly Dire Wolves?

• Despite genetic editing, the new wolves are not identical to the original dire wolves.
• According to a 2021 Nature study, dire wolves and grey wolves diverged around 6 million years ago, making them distant relatives despite appearances.
• Colossal is applying the morphological species concept, meaning that if an animal looks like a dire wolf, it can be classified as one.
  • However, millions of base-pair differences still exist between the two species.
    

Significance of the De-Extinction

• Scientific Achievement: This marks the first reported attempt to bring back an extinct animal species through genome engineering.
• Ecological Impact: If successful, dire wolves could play a role in restoring lost ecological functions.
• Technological Advancement: Showcases advances in genome sequencing, gene editing, and ancient DNA recovery.
  

Current Limitations

• The pups do not possess natural social behaviors, as they were raised without parents or packs.
• They are not allowed to breed, and Colossal plans to create only a few more individuals.
• Thus, a self-sustaining dire wolf population has not yet been achieved.
• It also raises debates about species classification, animal welfare, and the risks of reintroducing engineered species.