# Science Behind the photo: Fibonacci Numbers When we look at the bud of a rose, we see a striking example of a mathematical phenomenon found throughout nature, including in humans.

Born in the late 12th century, the mathematician Leonardo Fibonacci discovered the Fibonacci sequence and its surprising presence in nature. The Fibonacci sequence is a sequence of numbers in which the next number is found by adding the two numbers prior to it together. It starts: 0,1,1,2,3,5,8,13,21,34,55 Subsequently, dividing the larger number by the previous smaller number in the Fibonacci sequence always gives a number known as the golden ratio (φ), which is approximately equal to 1.618. The squares of sequential numbers in the Fibonacci sequence also tend to form a spiral shape which is seen throughout nature, for example in sea shells.

The Fibonacci sequence is also seen in rose petals. The average arc of the circle these petals follow during growth is 137.5˚, the golden angle. This arrangement is very efficient for the rose: as the petals grow out it allows the smaller ones to get sunlight, giving the rose even exposure to the sun throughout development.

Our bodies too are a prime example. The Fibonacci spirals can be seen in our ears, cowlicks, the shape of the human embryos and fists. Even the DNA double helix and our facial dimensions are thought to follow the golden ratio.

Interestingly, the section of our index finger from the tip to base of our wrist is larger than the preceding one by about the golden ratio 1.618. We also have two hands, each with five digits, and our eight fingers are each comprised of three sections: all Fibonacci numbers

Yodit Feseha is studying for an MSc in Human Molecular Genetics

Photo and words by Yodit Feseha