Human sperm has long been studied to find out how they move to reach their target with the first study dating back to nearly 300 years ago. Continually, the long belief of swimming by twirling their tails like propellers isn't as straight forward as we thought. Turns out that human sperm flick their tails lopsidedly and roll to balance out the off-center strokes. This was discovered by 3-D microscopy of human sperm swimming and then mathematically analyzing it for position data. The study done by Hermes Gaelha, a mathematician at the University of Bristol England shows that the movement is broken into two parts. The first part is a wiggle to only one side of the cell which resembles a person swimming with only one side of their body. The second motion is rotation which counteracts the one lopsidedness and allows the sperm to still move straight. These 3-D measurements are a big step forward in understanding the movement of sperm. With further study the research can be used to help diagnose and treat human infertility.