The new findings shatter old beliefs about Fibonacci spirals

A 3D model of a 407-million-year-old plant fossil has reshaped our understanding of leaf evolution. This study also provided new perspectives on the fascinating patterns observed in plants.

The leaf arrangements of early plants differ from those of many contemporary plants, challenging popular belief about the beginnings of the famous mathematical pattern observed in nature, according to recent studies. The results suggest that the typical spiral configurations of leaves that we see in nature now were not prevalent in the first land plants that first appeared on our planet.

Instead, ancient plants were found to have another type of snail. This disproves an old theory about the evolution of plant leaf spirals, suggesting that they evolved along two separate evolutionary paths. Whether it is the vast swirl of a tornado or the complex spirals of a tornado DNA Double Helix Spirals are common in nature and most of them can be described by the famous mathematical series Fibonacci sequence.

Named after the Italian mathematician Leonardo Fibonacci, this sequence forms the basis for many of nature’s most efficient and impressive patterns. Spirals are common in plants, with Fibonacci spirals making up more than 90% of spirals. Sunflower heads, pinecones, pineapples, and succulent houseplants all have these distinctive spirals in flower petals, leaves, or seeds.

3D printed fossil stems placed next to live lycophytes. Credit: Dr. Sandy Hetherington

Why Fibonacci spirals, also known as nature’s secret code, are so common in plants has puzzled scientists for centuries, but their evolutionary origin has been largely overlooked.

Based on their wide distribution, it has long been assumed that Fibonacci spirals were an ancient feature that evolved in the first land plants and became largely conserved in plants. However, an international team led by the University of Edinburgh has debunked this theory with the discovery of non-Fibonacci spirals in a 407-million-year-old plant fossil.

Using digital reconstruction techniques, the researchers produced the first 3D models of leafy shoots in a fossil algal plant Astroxylon maki – A member of the oldest group of leafy plants.

The exceptionally well-preserved fossil was found at the famous Rhynie chert excavation site, a Scottish sedimentary deposit near the village of Rhynie in Aberdeenshire. The site contains evidence of some of the planet’s oldest ecosystems – when land plants first evolved and gradually began covering the Earth’s rocky surface, making it habitable.

The results showed that leaves and reproductive structures in Astroxylon makiwere commonly arranged in non-Fibonacci spirals and are rare in plants today.

This changes scientists’ understanding of Fibonacci spirals in land plants. This suggests that non-Fibonacci spirals were common in ancient algae and that the evolution of leaf spirals diverged into two separate pathways. Ancient leaf mosses had an evolutionary history quite distinct from other major groups of plants today such as ferns, conifers, and flowering plants.

Spirally arranged leaves can be recognized at the tip of the fossil shoots Astroxylon maki. Fossil thin section number GLAHM Kid 2554 in The Hunterian Collections, University of Glasgow. Credit: Photo by Sandy Hetherington. Specimen number GLAHM Kid 2554 in The Hunterian Collections, University of Glasgow

The team created a 3D model of Astroxylon makithat became extinct more than 400 million years ago, through work with digital artist Matt Homepage, using digital rendering and 3D printing.

The study also included researchers from University College Cork, Ireland, Münster University, Germany, and Northern Rouge Studios, UK.

Dr Sandy Hetherington, evolutionary paleobiologist and project leader at the University of Edinburgh, said: “Our model of Asteroxylon mackiei allows us to examine leaf arrangement in 3D for the first time. The technology of 3D printing a 407-million-year-old plant fossil and holding it in your hand is incredible. Indeed, our findings give a new perspective on the evolution of Fibonacci spirals in plants.

Holly Ann Turner, who worked on the project as an undergraduate student at the University of Edinburgh and first author of the study, said: Astroxylon maki It is one of the oldest examples of plants with leaves in the fossil record. Using these reconstructions, we were able to trace individual spirals of leaves around the stems of these 407 million-year-old fossil plants. Our analysis of leaf arrangement in Asteroxylon shows that very early algae developed non-Fibonacci spiral patterns.

Reference: “Leaves and sporocysts evolved in rare non-Fibonacci spirals in early leaf plants” by Holly Ann Turner, Matthew Hombag, Hans Kirp, and Alexander J. Hetherington, June 15, 2023, Sciences.
doi: 10.1126/science.adg4014

The study was funded by UK Research and Innovation (UKRI), the Royal Society, and the German Research Foundation.