Cracking a tough case
For hundreds of millions of years, plants thrived in the Earth’s oceans, safe from harsh conditions found on land, such as drought and ultraviolet radiation. Then, roughly 450 million years ago, plants found a way to make the move to land: They evolved spores — small reproductive cells — and eventually pollen grains with tough, protective outer walls that could withstand the harsh conditions in the terrestrial environment until they could germinate and grow into a plant or fertilize an ovule. A key component of the walls is a polymer — a large molecule made up of many small subunits — called sporopollenin. It is durable and remains ubiquitous in all land plants to this day, but is absent in algae. Understanding the molecular composition of polymers found in nature is a fundamental pursuit of biology, with a long history tracing back to the early days of elucidating DNA and protein structures, but the toughness that...