Why can octopuses regrow limbs but humans cannot do that?

Question

Accepted Answer

The Biological Blueprint of Regeneration

Octopuses possess a remarkable capacity for cellular plasticity, which allows them to reorganize their internal tissues to regenerate lost limbs. This process relies on a unique set of genes and signaling pathways that remain active throughout their adult lives, enabling the creation of blastemas—specialized cell masses that develop into new, fully functional appendages.

Why Humans Struggle With Regeneration

Unlike octopuses, humans utilize a more complex immune system and rapid scar tissue formation known as fibrosis. While fibrosis is excellent for sealing wounds quickly to prevent infection, it unfortunately creates a barrier that prevents the complex cellular regrowth needed to form new limbs. Key biological differences include:

Genetic Silencing: Many regenerative genes that are active in embryos are permanently deactivated in human adults.
   Immune Complexity: The human inflammatory response prioritizes structural stabilization over long-term tissue restoration.
   Developmental Constraints: Humans are complex endotherms with highly specialized organ systems that prioritize efficiency over the slower, energy-intensive process of full-limb regeneration.

In summary, while humans have limited regenerative capabilities in tissues like the liver or skin, full limb regrowth remains a fascinating biological challenge, locked away by the evolutionary trade-offs between rapid healing and precise anatomical preservation.