Friday, January 29, 2016

Biologically Superfluous Phenomena

One of the perplexities of modern evolutionary theory is how structures, systems, and abilities evolved that are completely superfluous to an organism's survival. Natural selection, according to the theory, acts upon genetic variations, favoring those that suit the organism for its environment and culling from the population those which don't. But nothing in the theory explains, or at least explains well, biological extravagance, notwithstanding that we see such extravagance all around us.

Evolution News and Views, in observance of a new book that addresses this topic (Evolution: Still a Theory in Crisis) by biologist Michael Denton, has an essay up that discusses three examples of biological phenomena that far exceed anything that would have been necessary for fitness. The three are the Venus Flytrap, the stripes on a zebra, and the prodigious memory capability of the human brain. Here's what ENV says about the Venus Flytrap:
New work by researchers in Germany, published in Current Biology, shows that this plant can count! The team's video, posted on Live Science (see below), shows how the trigger hairs inside the leaves generate action potentials that can be measured by electrical equipment.

Experiments show that the number of action potentials generates different responses. Two action potentials are required to close the trap. When closed, the plant starts producing jasmonic acid. The third spike activates "touch hormones" that flood the trap with digestive juices. The fifth spike triggers uptake of nutrients. The struggling insect will trigger some 50 action potentials. The more they come, the more the trap squeezes tighter and tighter, as if knowing it has a stronger prey. The squeezing presses the animal against the digestive juices, also allowing more efficient uptake of nutrients.

"It's not quite plant arithmetic, but it's impressive nonetheless," says Liz Van Volken­burgh of the University of Washington in Seattle. "The Venus flytrap is hardwired to respond in the way that's now being described," she says.

Wayne Fagerberg at the University of New Hampshire in Durham agrees. "Obviously it doesn't have a brain to go 'one, two, three, four'," he says. "Effectively, it's counting. It's just not thinking about it."

In our experience, "hardwired" things that can count and activate responses are designed. This elaborate mechanism, involving multiple responses that activate machines on cue, seems superfluous for survival. The Venus flytrap has photosynthesis; it can make its own food. The argument that it needs animal food because it lives in nutrient-poor soil is questionable; other plants, including trees, do fine without animal traps.
Here's the video mentioned above. It's better to watch it at the link since the video is larger there:
How did such an astonishing ability, not just the ability to capture prey but also the ability to count, ever evolve through blind, purposeless processes in a plant?

Regarding the capabilities of the brain, a topic also discussed in the ENV article, I'm reminded of a quip by philosopher Alvin Plantinga who was discussing the brain's extraordinary ability to do higher math and reflecting on the implausibility of such an ability being adequately explained by a process that merely shaped human brains for reproductive dominance. Plantinga observed dryly that, after all, it's only the rare graduate student whose prospects for reproductive success are enhanced by his ability to solve differential equations.