March 1, 2011 12:14 am
Darwin Days Celebrated with the Evolution of Candy
Schaefer Hall’s lecture room was crowded on Feb. 14 as students, faculty, and community members congregated to see biology professor Bob Paul’s annual lecture on the evolution of candy as part of the Darwin Day celebration.
“For most of us, candy is just an unhealthy snack,” said biology professor Jordan Price, introducing Paul’s lecture. “But for Bob, it’s an obsession.”
Paul began the lecture with a well-received introduction on “lecture safety.”
Following a Vuvuzela horn by senior biology major Mike Studivan to start the event, Paul made sure to indicate the front and rear exits of the lecture room, how to use a barf bag, and even how to properly wear an oxygen mask (tied to a rope on the ceiling that Paul pulled down as needed) in the event of low cabin pressure in the lecture room.
“We’re all concerned about your health,” said Paul.
Paul began the sweet portion of his lecture with a discussion of the basics of evolution, important for those in the room who did not have a strong background in the subject.
The more modern belief is that species evolve by means of natural selection, when organisms with particular traits have an advantage over others in a certain or changing environment that leads to the continuation of that favorable trait in the population’s offspring.
This idea was introduced by Charles Darwin in 1859 with his book The Origin of Species.
“We have lots of ideas about what defines a species, but we don’t know for sure,” said Paul, explaining how science attempts to define a species based on morphological (if animals in question have distinguishable traits), biological (whether those animals can mate), or evolutionary (how different animals evolve over time) traits.
This process was begun by Carl Linnaeus who, in the 18th century, published the first book on binomial nomenclature, classifying species with a two-name system based on observed characteristics.
“Candies’ morphologies are similar to those of organisms,” said Paul. “So, what happened?”
Paul explained that as candy was faced with different environmental pressures and artificial (human) selection over time, new species began to be favored that could withstand those conditions, leading to the wide variety of candy that exists today.
Morphological changes in candy can even be seen on the inside of the candy itself.
After careful dissection experiments, Paul noticed that Jujubes, Dots, and Chiclets all have a primitive structure, an internal matrix of jelly, or cytoplasm.
However, other species (Hershey bars and Snickers) have a more advanced structure.
Members of the Milk Chocolate family, for example, have a wrapper epidermis that (upon careful removal and bilateral sectioning of the species Snickers) reveals a chocolate ectoderm (an outer tissue covering or “outer skin”) and nougat endoderm (inner tissue or “inner skin”).
Others species have even developed a mint endoderm to replace the nougat-filled center.
Paul hypothesized that the “crackle” layer of some candies migrated to the ectodermis over evolutionary time in certain species, while other complex changes generated species with new structures.
As Mounds developed a coconut endoderm and Almond Joys a large almond between the chocolate ectoderm and coconut endoderm, other species further adapted to selection pressures by developing a mesoderm (“middle layer” between ectoderm and endoderm) of caramel.
“These were strongly-favored adaptations,” said Paul, “and extremely valued and favored by natural selection.”
Paul also explained how other phenomena of natural selection, often observed in the organismal domains of Eukarya, Bacteria, and Archaea, can be seen in candies.
Convergent evolution, for example, which states that the same selection pressures on unrelated species can lead to those species developing similar traits, is observed in the Nestle and Mars families, where the former’s Oh Henry! bars are similar in internal morphology to the latter’s Snicker’s in their nougat endoderm and roasted peanut center.
“Is it possible that you get this adaptive radiation in these candies?” said Paul. “How do these candies change?”
Paul also discussed one of Darwin’s major discoveries on his way to publishing The Origin of Species. After noticing 13 finch species on the Galápagos Islands (west of Ecuador in the Pacific Ocean) and the different environments on each of the islands, Darwin proposed that an ancestral finch species, spread over all of the islands, began to diverge into several new species.
This occurred as each ancestral population developed distinctly different traits on each island to adapt to the selection pressures over evolutionary time.
Paul used this phenomenon (known as allopatric speciation) to explain the evolution of Hershey Kisses and Snow Caps, both with a similar shape but the latter with a sugar-covered top.
Beginning as one population of Hershey Kisses in an open plain with a mountain range, the candies were separated after a major environmental change caused the advancement of a glacier southwards that met with the mountain range, separating the population of Hershey Kisses across an impassable line of mountain and ice.
As the northernmost population began to adapt to cooler temperatures by selecting for a trait for “fur” (the sugar coating), the southernmost population maintained their furless structure.
Once the glacier receded, allowing both populations to intermingle again, they were two different species unable to successfully reproduce with one another.
Towards the end of the lecture, Paul discussed reproduction of the candies, and how the process itself has changed over evolutionary time in more advanced species.
While Tic-Tacs seem to reproduce by binary fission (division of one organism to create two identical copies), other candies with sexual dimorphisms (differences in morphology between genders) reproduce sexually.
Paul himself observed that while reproduction of Big Ones is unsuccessful between juvenile (smaller males) and females despite repeated attempts at fertilization, the behavior is successful between mature male and female Big Ones.
Further biochemical research of the 100 Grand genomic sequence (all of the DNA in an organism attributable to genes and composed of nucleotide bases), revealed sets of bases (or codons) that code for chocolate, caramel, nougat, and peanut structures.
These procedures took more than dissection procedures, and included homogenizing (blending) the candy, centrifugation, Polymerase Chain Reaction (PCR) purification, and sequencing to determine the genetic code.
“I’ve been thinking about things,” said Paul, discussing his future research plans at the end of the lecture. He hopes to study candy at the community level, understanding their social behaviors, cooperativity, caste systems, and even specialization.
After discussing his observations of a few of these traits in the field, Paul concluded the lecture with a final anecdote for the audience.
“Candy is fun,” he said, “and so is biology.”
“I can’t remember ever having this much fun on Darwin’s birthday,” said Walter Hatch, Professor of Biology at the College. “People come every year.”
“The ‘lecture safety’ part was hilarious, and the lecture shows that not all science is boring and serious,” said Studivan.
“Hopefully the other students will have walked away with more knowledge about Darwin and his work on evolution.”