Paleontology and molecular biology - Essay Example

Biology 09 October Integration of Fossil and Molecular Data Integrating fossil and molecular data is just like opening a door to endless amazing discoveries on how the body of living creatures was formed. It has been established that molecular data along with morphological data played important roles in giving vivid details on the history of evolution. While it is true that molecular data or DNA data results to documented sequence of various events in the evolutionary development of specific specie, it cannot achieve any success in deciphering the evolution of species that lived hundreds or millions of years ago through fossils.

It is in this regard that fossils must be cited in providing the present generation a unique opportunity to know evolutionary history and help scientists or interested groups in preserving some combinations of primitive and discovered characteristics of living things that are non-existence in extant taxa. Fossils, therefore, are very critical in documenting the character transformation sequences over a long period of time that cannot be achieved in modern times by the lone use of molecular data.

The integration of fossil and molecular data has been well established in the book of Neil Shubin “Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body.” It all started with the discovery in 2004 by Shubin, Ted Daeschler, and Dr. Farish A. Jenkins, Jr. in the Arctic of the fossil of a fish, which they named Tiktaalik. The emergence of Tiktaalik fossil from the rock was a beautiful intermediate between fish and land-living animals (Shubin 22). Tiktaalik has a shoulder, elbow, and wrist composed of the same bones as an upper arm, forearm, and wrist in a human (39).

Tiktaalik was just the beginning of the evolution of creatures living in water to land-living animals. It was just the tip of the iceberg, so to speak. With fossils, experiments cannot be done to reach a conclusion. Enter the role of the genes. To understand the difference of each cell in the body, it is imperative to understand the genetic switches that control the activity of genes in each cell and tissue (46). Experiments can be performed wherein the genes can be manipulated to see how bodies actually change in response to different conditions or stimuli (47).

The discovery of the zone of polarizing activity (ZPA) in the 50s and 60s by biologists Edgar Zwilling and John Saunders (49) and the Sonic hedgehog in the 90s by Cliff Tabin, Andy MacMahon and Phil Ingham (52) contributed to the role of genes in the evolutionary development. ZPA was responsible for the development of the limb as found out by Zwilling and Saunders in the process of their experiment with the embryos of chicken egg: remove it early will result to the development of just the upper arm or a piece of an arm; remove it slightly later, the upper arm and forearm are developed; remove it even later will result to the development of almost complete arm but with digits that are short and deformed (49).

The experiments of Tabin, MacMahon and Ingham on the Sonic hedgehog of fruit fly, on the other hand, revealed that Sonic hedgehog is one of dozens of genes that act to sculpt the limbs from shoulder to fingertip by turning on and off at the right time (53). Another experiment done by Randy Dahn with the supervision of Shubin, on the embryos of shark and skates to see whether Sonic hedgehog’s role in limbs is unique to limbed animals showed that: Sonic hedgehog turns on at the same time in the fin development of skate as well as in the development of limbs in chicken; it turned on in the patch of tissue at the back end of the fin which is equivalent to the human pinky; and injecting the skate egg with vitamin A resulting to the hedgehog to turn on the opposite side of the limb much the same way with that of the chicken (54).

The experiments proved that all appendages, be they fins or limbs, are developed by similar types of genes. In the final analysis, Shubin disclosed that great evolutionary transformation did not involve the origin of new DNA. The genetic switches on ancient genes produced the evolutionary development from fins to limbs with fingers and toes (58) in order for the creature to adapt to its environment. Work CitedShubin, Neil. Your Inner Fish: A Journey into The 3.5-Billion-Year History of the Human Body.

New York: Pantheon Books, 2008. Print.