Scientists at Kyoto University have made a groundbreaking discovery about the way sperm swim, which defies one of the fundamental laws of physics. According to a study published by Leiden University, the sperm’s flagella, or tail, propels the agents forward by changing their shape to interact with the surrounding fluid.
Traditionally, Newton’s law of motion states that there should be an equal and opposite reaction to an object in motion. However, the research team found that sperm do not elicit this reaction from their surroundings. Instead, they whip their tails without releasing much energy into the fluid.
The elasticity of the sperm tails should expend more energy and hinder mobility. The researchers used human sperm cells and algae for their study, as both have flagella that help them move through liquid. The tails are elastic and can deform and return to their original shape, which should not allow them to swim through the obstacle-like liquid.
Under a microscope, the team found that the sperm and algae use wave-like movements of their tails to push and pull themselves through the fluid. This movement method goes against Newton’s law of motion, which would predict that the movements ultimately slow the swimmers down.
The researchers call this ability “odd elasticity.” By bending in tiny ways in response to the liquid’s resistance, the flagella are able to conserve energy by averting an equal and opposite reaction. This “odd elasticity” is not a generic term for activity in solids, but rather a well-defined physical mechanism that generates active forces in solids or other systems.
This groundbreaking discovery sheds light on the complex and intricate movements of sperm and challenges our understanding of basic physics principles. Further research will be needed to fully understand the implications of this finding.
The study provides valuable insights into the mechanics of sperm and may have implications for fertility treatments and understanding how sperm navigate to fertilize an egg. It also raises questions about the potential impact on human reproduction in a world increasingly affected by pollution, as recently highlighted in a separate study pointing to the damaging effects of pollution on sperm.
As scientists continue to unravel the mysteries of sperm motility, this research opens up new avenues for understanding and potentially manipulating reproductive processes.