Gene editing technologies (such as CRISPR-Cas9) that give humans the characteristics or abilities of other species are still in the theoretical exploration and early experimental stages. Such attempts involve complex biological challenges, ethical disputes, and technical limitations. The following is an analysis of the possible directions and key issues for achieving similar “underwater breathing capabilities”： --- ### **1. Biological basis of target ability** **Underwater breathing mechanism of fish**： -**The structure of the gills**: The gills efficiently extract dissolved oxygen from the water through a thin layer of epithelial tissue and a network of high-surface blood vessels. -**Hemoglobin optimization**: The hemoglobin of some fish has a very high affinity for oxygen and adapts to a low-oxygen environment. -**Lactic acid metabolism**: Some fish (such as whale sharks) can reduce the accumulation of lactic acid after exercise through special metabolic pathways and support long-term activities. **Human biological limitations**： -The lungs cannot directly extract oxygen from the water. -The oxygen binding ability of human hemoglobin is different from that of aquatic organisms. -The underwater high-pressure environment may cause physical damage to the lungs. --- ### **2. Possible gene editing directions** ####**Direction 1: Simulate the function of the gill** -**Cross-species gene introduction**： -Try to introduce genes that control gill development in fish (such as the Hox gene family and genes related to the FGF signaling pathway), but the mechanism of mammalian embryonic development is very different from that of fish, and direct transplantation may lead to uncontrollable consequences (such as deformities or cancer). -Use bioengineering to build artificial gill devices (such as bionic organs through 3D bioprinting) outside the human body, rather than directly modifying human genes. ####**Direction Two: Enhance the oxygen utilization efficiency of the lungs or blood** -**Optimize hemoglobin**： -Edit human hemoglobin genes (such as HBB) to improve their binding ability to oxygen or acid resistance (refer to the hemoglobin characteristics of deep-sea fish). -Introduce mutations in myoglobin in certain marine mammals (such as cetaceans) to enhance oxygen storage capacity. -**Metabolic adaptation**： -Modify the mitochondrial function of muscle cells to imitate the efficient anaerobic metabolism of fish. -Introduce genes that are resistant to low-oxygen environments (such as stable mutants of HIF-1a) to help cells survive under low-oxygen conditions. ####**Direction Three: Path of symbiosis or synthetic biology** -**Cooperation with symbiotic microorganisms**： -Edit the microflora of the skin or digestive tract so that it can decompose water to produce oxygen (similar to the symbiotic relationship between certain aquatic insects and algae). -**Artificial organelle**： -Design synthetic biological components (such as artificial peroxisomes) to help cells directly use oxygen in water. --- ### **3. Technical challenge** -**Multi-gene regulatory complexity**: Aquatic respiration involves the synergy of dozens of genes, which far exceeds the precise regulatory capabilities of current gene editing technologies. -**Developmental and anatomical disorders**: The formation of gills requires the differentiation of specific tissues during embryonic development, and new organs cannot be naturally generated in adults. -**Immune rejection and side effects**: Cross-species genes may be recognized by the human body as foreign objects, triggering an immune response or causing gene dysfunction (such as carcinogenic risks). -**Ethics and safety**: Non-therapeutic gene enhancement may violate bioethical principles, and irreversible genetic modification may affect future generations. --- ### **4. Alternative (non-gene editing)** -**Exoskeleton and bionic equipment**: Development of wearable artificial gill devices to filter oxygen in water through nanomaterials. -**Synthetic blood substitute**: Synthetic blood carrying fluorocarbon compounds is injected to enhance oxygen carrying capacity (it has been experimented in some medical scenarios). -**Drug induction**: Epigenetic regulatory drugs temporarily activate the body's potential genes for hypoxia resistance (such as genes related to plateau adaptation). --- ### **5. Ethics and Social impact** -**Human identity controversy**: Cross-species genetic fusion may challenge the definition of ”human" and cause social, cultural and philosophical disputes. - **Ecological risks**: If gene editing humans are accidentally released into the environment, it may destroy the ecological balance. -**Fairness issues**: Technology may only be used by the privileged, exacerbating social inequality. --- ###**Conclusion** At present, the underwater breathing ability of human fish through gene editing is still in the category of science fiction. A feasible path in the short term is more likely to be **Gene therapy combined with external technical assistance** (such as artificial gill devices). In the future, if technological breakthroughs occur, it may be prioritized for medical fields (such as the treatment of respiratory diseases) rather than directly for human enhancement. The scientific community needs to establish a strict ethical framework and regulatory mechanism while exploring technology.