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In 1879 Charles Darwin wrote a letter to botanist Joseph Dalton Hooker. Darwin was troubled by an “abominable mystery,” and he hoped that Hooker could help solve it. The mystery that so bothered Darwin related to plants — specifically to flowering plants. He wondered why there are so many flowers.
To understand Darwin's mystery we need a little background. In 1859 Darwin published his famous book On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life. In the book, Darwin presented his theory that all species of living things evolved from a common ancestor by the process of natural selection over very long periods of time. The diversity of life, Darwin suggested, arose by common descent from that ancestor into a branching tree of evolution. One of those branches eventually resulted in human beings. Over the next two decades, Darwin's ideas came to be accepted by many scientists.
Darwin's book became the foundation for evolutionary biology. But there were some things that did not seem to fit with Darwin's theory, and he was troubled by that. He recognized that the oldest plant fossils are of gymnosperms. The name gymnosperm comes from two Greek words meaning “naked seeds.” Plants in that classification include plants that do not flower or produce fruit. The seeds are “naked” compared to angiosperms which are flowering plants that enclose their seeds in a fruit.
Examples of modern gymnosperms are pine, spruce, fir, cedar, ginkgo, and tropical plants called cycads. The seeds of gymnosperms are open to the air where they can be pollinated by wind or sometimes by insects. Angiosperms have seeds which are enclosed in a fruit which develops from the ovary of the plant. Pollination of angiosperms is much more complex requiring assistance from living creatures. Examples of angiosperms are all kinds of flowering plants such as violets, roses, and daisies. It also includes grains such as wheat and flax and trees such as maples and oaks. Plants such as tomatoes, peppers, spices, and, of course, all kinds of fruit trees are angiosperms. The planet is full of angiosperms.
Gymnosperms can reproduce with just airborne pollen. Pollination and therefore reproduction of angiosperms involves insects and animals of various kinds. Angiosperm reproduction requires bees, bats, ants, birds, or other creatures. Many angiosperms require specific insects or animals. Without those pollinators, angiosperms could not survive, and without the angiosperms, their pollinators could not survive.
The fossil record indicates that gymnosperms were doing well until a huge number of angiosperms suddenly appeared on the scene and took over the world. That was what mystified Darwin. According to his theory, new species come into existence very slowly over a long time because of natural selection. To add to the problem, angiosperms also require the existence of the insects and animals that pollinate them. The angiosperms cannot reproduce without them. How could those pollinators have arisen so quickly by natural selection with just the right features to pollinate the angiosperms`? For Darwin, it was an “abominable mystery.”
Science is still searching for the answer to Darwin’s mystery. Recently the journal PLOS Biology published (January 11, 2018) a scientific paper suggesting a possible explanation for the rapid takeover by angiosperms. It was written by the leaders of the study, Kevin Simonin, assistant professor at the University of California, Berkeley, and Adam B. Roddy, a postdoctoral fellow at the Yale School of Forestry and Environmental Studies. What the authors theorize is that angiosperm supremacy can be explained by genome downsizing. They wrote, “Smaller genomes permit the construction of smaller cells that allow for greater CO2 uptake and photosynthetic carbon gain.” Angiosperms, they say, developed smaller cell sizes, so they were more efficient in capturing carbon dioxide and water for photosynthesis.
The popular media published the announcement, “Scientists Finally Solve Charles Darwin's ‘Abominable Mystery’ Where Did All the Flowers Come From?” So the mystery is now solved, and Darwin can rest in peace. Or can he? The authors wrote that “Genome downsizing occurred only among the angiosperms.” The next question to address might be, “Why did downsizing not occur among gymnosperms?”
The report said that smaller cells made it possible for the leaves of the angiosperms to have smaller veins for the movement of xylem, the liquid that flows through the plant carrying water and nutrients. However, making the veins in the plant leaves smaller caused increased restriction to the flow of the fluid. The report says that to overcome the restrictions of the veins “other innovations in xylem anatomy that reduce hydraulic resistance have been hypothesized … .” So there are still mysteries to solve.
It seems to me that, at best, even if we understood all of these changes to the angiosperms we would solve only part of the mystery. Pollinators were needed at the same time the angiosperms came into existence. Also, the pollinators are dependent on the angiosperms for their survival in a symbiotic relationship. In spite of the greater efficiency of the angiosperms, they needed pollinators to allow them to reproduce. The suggestion is that the pollinators “co-evolved” to enable the surge of angiosperms.
Obviously, there are still mysteries surrounding the abundance of flowering plants. As we enjoy the beauty of the flowers and the nourishment of their fruits, we contemplate the meaning of it all. I am not proposing a “God of the gaps” to explain the mysteries that have not yet been solved. I do not believe that they are miracles that cannot be understood. As scientists continue to study plants, they will eventually solve more of the mysteries. Perhaps, someday we will know all of the answers of how God did it.
I am suggesting that the amazing complexity of the whole system shows evidence of wisdom and intelligence. As we look at all of the complex design that is evident in living plants and animals and their mutual dependence on each other, it takes a great leap of faith to believe it all happened by chance. The authors of the study refer to “innovations that reduced minimum cell size.” Innovations require an Innovator.
So two decades after Origin of Species, as Darwin's ideas were becoming widely accepted, Darwin continued to ponder the mystery. “Wh are there so many flowering plants?” Perhaps it was because God knew that we would need them and he had a design in mind. We are still trying to understand the mind of God.
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