The reason dead bodies float while living bodies tend to sink has to do with changes in the body’s composition after death. When a person is alive, their body contains a significant amount of water and air, which are distributed throughout different tissues, helping maintain buoyancy. However, after death, several things happen that affect buoyancy.
First, when the body starts to decompose, the tissues break down and produce gases, such as methane and carbon dioxide.
These gases accumulate in the body’s cavities, particularly in the abdomen, making the body more buoyant. As these gases fill the body, it creates an internal pressure that can cause the body to rise to the surface of water.
Additionally, living bodies have muscle mass and bone density, which are relatively dense compared to water. This density causes living bodies to sink when they fall into water because they are heavier than the volume of water they displace. Over time, as decomposition progresses, the muscles and tissues lose mass, and the body’s overall density decreases, allowing it to float.
It’s important to note that floating or sinking can also be influenced by external factors such as body fat, which is less dense than water. People with higher body fat may float more easily, whether alive or deceased. However, after death, the combination of gases and changes in tissue density generally leads to floating, while living bodies have a tendency to sink due to their higher overall density.