Gene editing technologies (such as CRISPR-Cas9) do provide unprecedented possibilities for humans to transform their own biological characteristics, but at present, to achieve the ability of fish-like underwater breathing still faces huge scientific, ethical and safety challenges. The following is the analysis of key points： --- ### **1. Scientific feasibility analysis** ####**Target feature: Underwater breathing** Fish extract dissolved oxygen from water through their gills, while humans rely on their lungs to breathe air. To achieve similar functions, it needs to be solved： -**Oxygen exchange system**: The surface area of the gills is large and rich in blood vessels. It is necessary to transform the human respiratory system or add gill-like organs. -**Oxygen perception and metabolism**: Fish have special hemoglobin (such as antioxidant free radical protein) and hypoxia-resistant metabolic pathways (such as HIF-1a signaling pathway). -**Saline balance**: Fish living in seawater have special ion regulation mechanisms (such as chlorine-secreting cells), and human kidneys need to be modified accordingly. ####**Possible gene editing directions** -**Introduction of gill development genes**: Such as **Foxi3**, **Eya1** and other genes that regulate gill formation in fish, but how to form functional organs in the human body is still a difficult problem. -**Enhance hypoxia resistance**: Edit genes related to the human HIF pathway (such as HIF-1a), or introduce genes for hypoxia resistance of cetaceans and seals. -**Modified hemoglobin**: It mimics the hemoglobin variants of deep-sea fish (such as anti-stress folded globulin). --- ### **2. Technical challenge** -**Multi-gene regulation**: Underwater breathing involves the synergy of hundreds of genes, which far exceeds the current editing capabilities. -**Organogenesis**: Gills or ancillary respiratory organs require complex 3D tissue and blood vessel networks, which cannot be achieved with prior art. -**Off-target risk**: CRISPR may cut key genes by mistake, causing cancer or immune problems. -**Developmental compatibility**: The structure of the adult human body has been stereotyped, and embryo editing has caused ethical controversy. --- ### **3. Ethics and Security issues** -**Human identity dispute**: Cross-species gene mixing may challenge the definition of ”human nature". - **Ecological impact**: If technology is popularized, it may change the relationship between human society and nature (such as ocean colonization). -**Increased inequality**: Technology may only be used by the rich, deepening social divisions. -**Long-term health risks**: Unknown physiological side effects (such as immune rejection or metabolic disorders). --- ### **4. Alternative** The current more realistic path may be： -**Bionic equipment**: Development of artificial gills (such as filtering oxygen in water with nanomaterials). -**Drug-assisted**: Temporarily enhance underwater survivability by activating hypoxia-resistant pathways (such as plateau-adapted drugs). -**Symbiotic biotechnology**: The use of transgenic microorganisms to assist oxygen supply (such as customized algae). --- ### **5. Current situation and future prospects** As of 2023, gene editing is still mainly used for the treatment of single-gene diseases (such as sickle anemia), and complex cross-species transformation is still in the realm of science fiction. May be implemented in stages in the future： 1. **Short-term**: Enhance the body's resistance to hypoxia (used in medical or aerospace). 2. **Mid-term**: Local tissue improvement (such as skin-assisted breathing). 3. **Long-term**: Organ cell transformation (requires breakthroughs in stem cells and synthetic biology). --- ###**Conclusion** Although gene editing provides theoretical possibilities for the expansion of human capabilities, cross-species transformation such as underwater breathing is extremely unrealistic under the current scientific framework. Future breakthroughs need to rely on interdisciplinary cooperation (synthetic biology, developmental programming, ethical governance) and strictly evaluate the risk-benefit ratio. In this process, the discussion of social consensus and ethical boundaries may be more critical than the technology itself.