August 13, 2021 | David F. Coppedge

Sunflower Science Without Darwinism

Researchers do good work on sunflowers without
descending into Darwinian storytelling

 

Is it possible to do biology without evolution? Can you even talk about fitness and reproductive success without attributing it to blind forces of nature? After all, healthy species do reproduce successfully, or else they would be extinct. Noting that does not require making up a just-so story about how they got that way.

Why Sunflowers Face East (UC Davis). This press release looks ripe for Darwin storytelling, but evolution is nowhere mentioned. Instead, the article starts with amazing facts about sunflowers as they grow.

Amazing FactsWhile sunflowers are growing, their heads turn back and forth to track the sun during the day. Previous work from Harmer’s lab showed that this tracking is controlled by the plant’s internal circadian clock.

But as the flower heads, or capitula, mature and their stems become stiff and woody, this movement decreases until the heads are all facing the morning sun.

The article tells other interesting facts. There may be hundreds or even thousands of individual florets in a single sunflower head. “These individual florets develop first at the outer edge of the flower head, forming characteristic spiral patterns.”

This spiral pattern is beautifully rendered in Cristobal Vila’s stunning animation, Infinite Patterns on YouTube. His earlier animation, Nature by Numbers, demonstrates how it follows the Fibonacci Series known to mathematicians.

The UC Davis team’s approach to understanding why sunflowers face east matches that of a winning high school science project. They turned some mature potted sunflowers to face west in the morning, then counted how many bees visited the flowers. More bees visited the east-facing plants, they observed. To test a hypothesis that warmth was a key factor, they heated the west-facing flowers with a portable heater. Bee visits increased. They studied the quality of east-facing and west-facing seeds. Here’s another test they ran:

Finally, Evan Brown, an undergraduate student supervised by Ben Blackman at the University of Virginia, took sterile male plants, which could produce seeds but not make pollen, and surrounded them with normal plants facing east or west. Using genotyping, they were able to distinguish whether the male-sterile plants were pollinated by east- or west-facing plants. The team found that pollen from the east-facing plants was responsible for more offspring than that from west-facing plants.

Sunflowers facing east in Colorado (DFC)

In conclusion, the plant biologists at the university found some good reasons for sunflower behavior. Why do they face east? Here’s a quick summary of the findings:

  • Morning light warms the flowers, which attracts more bees (see video clip in the article).
  • Direct sunlight increases bees’ visual perception of UV light reflected from the flowers.
  • More bee visits leads to more pollination, which increases the number of seeds produced.
  • Seed quality was better from east-facing plants: the seeds were larger and heavier.

It would have been tempting for this team to launch into just-so stories about how this behavior evolved. But they didn’t. The abstract from the paper in New Phytologist doesn’t mention evolution either. The paper’s introduction whizzes past a couple of statements that “plants have evolved” some traits or adaptations, but there is no mention of natural selection anywhere. Darwinism did not play a functional role in the research. The e-word “evolved” appears tacked on as if by editorial necessity.

They talk about “reproductive success,” which might sound like a Darwinian concept, but that doesn’t require belief in evolution either. They mention fitness, but fitness just means “health” when detached from Darwinism. Cattle ranchers want their cows and bulls to have reproductive success, don’t they? Are they thinking about Darwin when they do what is needed to keep cattle healthy? Clearly not. In this case, it was observed that sunflowers facing east produce healthier seeds, so they face east. Sunflowers reproduce better facing east, so they are found to face east. How they got that way is somebody else’s question to answer. Scientists should leave it at that.

This science project focused on observation and hypothesis testing. It added to science’s understanding of plant behavior, circadian rhythms, mathematical spirals, pollination, symbiosis, and health. As a result, the findings could help farmers plant their crops for more productivity. No evolution required. The researchers may indeed be Darwinians, but their work shows that Darwinism was not essential to their science.

Science used to pride itself on observation and hypothesis testing. Before Darwin, many scientists were averse to engaging in metaphysical speculations about how things came to be. The emphasis in science education was on the data, measurements, repeatability, testability and integrity. When scientists set a good example like this, we like to point that out.

An engineering perspective can bring valuable data to the enterprise of good science. Engineers understand requirements; it’s their bread and butter. What are the requirements for a circadian rhythm that can make a machine track the sun? What are the requirements for having a machine end up facing east when it loses the flexibility to turn? What are the specifications for those requirements? Finally, what are the causes that are necessary and sufficient to bring those requirements to a functioning system? Engineers can try building machines able to do these things.

When engineering requirements are brought to consideration for producing a sunflower mimic, and a sunflower that can make seeds to grow baby sunflowers, evolutionists will most certainly head for the hills screaming.

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