Radical Pedagogy (2003)
ISSN: 1524-6345
Which Came First, The Chicken or The Egg?
A Foul Metaphor for Teaching
Randy Garner
Sam Houston State University
ICC_RLG@exchange.shsu.edu
Abstract
As educators we should strive to inform our students, challenge their assumptions, and enlighten their minds. Occasionally educators may fall into the trap of overusing certain inaccurate popular phrases or expressions. At a recent conference, a speaker repeatedly peppered his remarks with the phrase “it’s a chicken and egg thing” to the point of exhaustion of the audience and to the detriment of his intended message. The seeming paradox as to whether the chicken (Gallus domesticus) or the egg (Gallus prezygoticos) first emerged in evolutionary history has become a metaphor for a circumstance or a condition in which no clear causal or temporal order can be determined. As a response, the present paper provides a historical, archeological, evolutionary, and humorous treatise to answer this question in order to resolve this dilemma. Using this amusing debate as a foundation, the author discusses the pedagogical uses of humor and metaphor.
Which Came First, The Chicken or The Egg?
A Foul Metaphor For Teaching
The seemingly tautological question of whether the domestic chicken (Gallus domesticus) or the egg (Gallus prezygoticos) first emerged in evolutionary history has often been visited by many speakers. This enduring debate has manifested itself as a metaphor for a circumstance or a condition in which no clear causal or temporal ordering can be determined. In considering the use of this seemingly flawed metaphor, it is astonishing that such a debate could remain contentious, given the shear weight of scientific and historical evidence. In fact, there really is no support for the continued use of this inaccurate metaphor and to do so may demonstrate a lack of logical sophistication.
The conundrum posed by the inquiry as to “which came first the chicken or the egg?” the perceived paradox is as follows. The chicken could not have come first because it must hatch from an egg. Conversely, the egg could not have come first, as it must have been laid by a chicken. While seemingly contradictory, a brief examination of history, archeological records, and evolutionary theory provides the solution.
Chicken Tick’In: Time and History
According to fossil records, the present-day chicken is believed to be a descendent of Archaeopteryx, a creature with sharp teeth and winged claws, found in the Jurassic period and thought to be more than 150 million years old. According to Augusta (1961), Archaeopteryx is “a true bird, occupying the phylogenetically lowest place in the class of birds (Aves) and is the only member of the ancient group of the Archaeornithes (or Saururae); all other birds, whether extinct or extant, belong to the higher group of Neornithes (or Ornithurae)” (p.56). These upper Jurassic birds were not much larger than a pigeon and, like chickens of today, were not good flyers.
More recent evidence (Chatterjee, 1997) suggests that the Protoavis Texenis from the late Triassic period may actually predate Archaeopteryx by some 75 million years. The evidence, however, requires a much more complex understanding of comparative anatomy, as this discovery did not reveal a feather structure found with later fossils of the Archaeopteryx. Fossil records also demonstrate another bird identified as Confuciusornis (so named as a result of its discovery in Northern China) is similar to Archaeopteryx but lacks teeth. Experts believe that Confuciusornis may have occupied this same historic period.
According to Paul (2002) the evidence that birds evolved from small predatory dinosaurs in Mesozoic times is overwhelming. Paleontologists now agree that birds are the direct descendents of dinosaurs. The many inhabitants of the Jurassic era, including the most commonly identified dinosaurs, were egg layers. Even during the Jurassic period there were chicken-sized, egg-laying predators identified as Compsognathus. The similarities in modes of reproduction between avepod dinosaurs and birds extend to the sharing of a distinctive eggshell microstructure not observed in other amniotes (Paul, 2002). Reproduction by means of external egg laying allows the evolving dinosaurs to produce large numbers of offspring without the additional weight (and associated diminishment of mobility) of an internal gestation process. According to archeological theory, birds evolved from dinosaurs, which, in turn, evolved over millions of years from the primordial goo that produced single-cell organisms. Many forms of birds, including the precursor to the modern chicken, continued to develop through the Cenozoic era and by the Oligocene period, over 35 million years ago, most of the relatives of the birds we know today had appeared. In fact, the dinosaur-to-bird lineage can better be divided according to non-avian dinosaurs and avian dinosaurs.
Consistent with evolutionary theory, Dingus and Rowe (1998) have suggested all living birds belong to either the Neognath lineage, which includes the Gallus gallus (chicken) or the Palaeognath. Further, the Neognath lineage split into two distinct lines during the Cretaceous period. One such split includes the anseriforms plus the galliform birds, such as chickens and turkeys.
Scientists have identified that domesticated chickens (Gallus domesticus) were descendants of the Red Jungle Fowl (Gallus gallus) and appeared as early as 4,000 BC in Southeast Asia. The domesticated chickens were initially used for entertainment in the form of cock fighting, rather than food. However, by 1400 BC the domestic chicken was popular throughout Asia and Europe and chicken eggs were hatched in mass incubators.
In sum, birds of today are ancestors of amphibian life that evolved from an aquatic existence to survive on dry land during the warm period of Perm. These predatory creatures, or Reptilia, were generally diminutive and slim with elongated posterior limbs. Reproduction by means of eggs is found in all such reptiles and the trait continued during the evolutionary period in which reptilia variants became warm-blooded, developed feathers, and began to master flying. In short, they became birds; that is, including those that we later identified as chickens.
Chicken Opposition
Chicken Evolution
Consistent with evolutionary change, the genetic mutations resulting in the present-day chicken seems to have occurred over millions of years. On occasion the mistakes, changes, or mutations that occur in the evolutionary process produce a creature that is not the same as the parents and others of its former species. Many times these new creatures may be less well adapted to the environment and not survive. However, with changes in the climate and flora and fauna, the addition of feathers, changes in bone structure, and the ability to take flight allowed the new creatures—avian dinosaurs—to thrive, while the less well-adapted ancestor was lost to extinction
Prior to the arrival of the chicken, a pre-chicken creature that was at least one generation away from our present-day chicken, laid an egg that contained an embryo with DNA consistent with the “new” aviary creature known as chicken. Therefore, the egg that contained the newly evolved chicken preceded its hatching. In other words, prior to the arrival of the first zygotic mix of male and female pre-chicken DNA that combined or mutated to form today’s chicken, there were only non-chickens. The DNA mutations occurred at the cellular level in the zygote developing inside the egg. Therefore, the egg clearly preceded the chicken.
Darwinian Chicken
A further analysis of Darwinian theory finds that all animals were preceded by, and evolved from, ancestors that were not exactly like them. Changes in DNA as a result of the combinations of mutation, mistakes in DNA repair, ecological affects, and other influences allowed for the development of creatures that more harmoniously coexisted with the changing environment. As a result, with each successive evolutionary change, there is necessarily a creature that lacked the characteristics of that which later evolved. In the case of birds, including chickens, the eggs of the pre-evolved creature contained the newly evolved living animal. Specifically, a pre-chicken laid an egg that contained the newly evolved chicken. Thus, from the Darwinian perspective, we clearly find that the egg preceded the newly evolved chicken.
In simplest terms, we may make several assumptions: a) millions of years ago, ancestors of the present day chicken did not contain the exact DNA or other characteristics of today’s chicken—thus, this was not a chicken; b) this pre-chicken was probably the ancestor of several egg-laying avian dinosaurs; c) each successive generation of these ancestral birds resulted in creatures that more closely approximate what we now know as a chicken. In an evolutionary timeline, we can see the result of our assumptions, and the answer to this alleged dilemma becomes clear:
Jurassic Non-Chicken » Egg » Triassic Non-Chicken » Egg » || History Continues || » Great Grandmother of Chicken » Egg à Grandmother of Chicken » Egg » Mother of Chicke
