Tiktaalik is a northern native Canadian name for freshwater fish. This creature supposedly lived 365 million years ago. Its discovery in 2004 created quite a stir, not so much for its fossilized structure, but for the manner in which it was discovered.
More than a decade ago, Edward Daeschler, Neil Shubin, and Jennifer Clack decided that the best place to look for an elusive transitional fossil bridging the divide between fish and tetrapods was in Nunavut in northern Canada. This region, although now in the Arctic Circle, was once thought to be near the equator and to have a warm climate. So in 1999 they sent research teams to Ellesmere Island (77° 3'37.23"N; 88° 5'52.40"W) to look for transitional fossils in an area where an intermediate animal would most likely be found.
After 5 years of digging with little success, the researchers discovered what they had been looking for: a fossilized fish-tetrapod looking animal. The animal had characteristics similar to a fish but with skeletal characteristics akin to a crocodile. Its skeletal structure enabled it to support itself on land and water, and the presence of spiracles (small holes) on its flat head suggests that the animal had primitive lungs, in addition to gills.
Notwithstanding the impressiveness of this discovery, it does not rise to the level of what we might call definitive scientific evidence because it was not a crucial test of macroevolution. What is a crucial test? Let’s consider a brief example from Relativity.
When Einstein introduced his theories of Special Relativity and Relativity in the early 1900s, his ideas created a stir. Back then Newton was still revered as the undisputed champion of science and the thought of anyone challenging Newton’s ideas was considered heretical. However Einstein boldly challenged Newton’s ideas. He argued that space and time are not constant as Newton had supposed; rather space and time differed based on one’s state (hence the name “relativity”).
Searching for ways to test Einstein’s theory, scientists decided to study the light from stars next to a fully eclipsed sun. If Einstein was right then the sun’s gravity well would cause the light from ‘nearby’ stars to bend and thus appear shifted in the dark sky. And so in 1919 a British research team headed by Sir Arthur Eddington went on a distant journey to view a solar eclipse on Principe Island near the coast of Guinea in West Africa.
It was cloudy during the days leading up to the eclipse and a heavy thunderstorm rolled through the team's location on the morning of the much anticipated event (May 29th). The research expedition was in jeopardy of failing, nevertheless Eddington and his team set up their instruments and hoped for a miracle. Minutes before the eclipse when the sky was still overcast, anxieties grew as the moon moved in front of the sun and the sky darkened. Then suddenly, before the eclipse reached totality, the clouds parted revealing the corona of the sun and surrounding stars. The team quickly snapped their photos.
The photos revealed that light from ‘nearby’ stars (in the Hyades star cluster) had indeed shifted, as Einstein predicted. The sun’s gravitational pull shifted the position of the stars an average distance of 1.6 arcseconds. Like Tiktaalik, it was an amazing discovery.
The Crux of the Matter
Tiktaalik’s discovery provides reasonable evidence for accepting macroevolution, and Eddington’s eclipse study provides reasonable evidence for accepting Relativity, but the quality of evidence from these two studies are not on par. The essential difference is that one was a crucial experiment and the other was not.
A crucial experiment is one where a “do or die” scenario is set up that allows us to tentatively decide on the truth or falsity of a theory. Relativity was subjected to a do or die test and it survived. The bending of starlight around the eclipsed sun allowed us to ascertain with a great deal of certainty that Einstein was right. If the light had not bent, we would have had good reason to conclude that Einstein was wrong and we might still be going with Newton’s theory.
Tiktaalik, although an important and impressive discovery, was not a crucial test of macroevolution. By this I mean that Tiktaalik did not create a situation where the theory of macroevolution was subjected to a “do or die” scenario. If the Ellesmere research team had never discovered Tiktaalik then the theory of macroevolution would not have been any worse off. Explanations would have included, “Well, we’re not looking in the right place,” or “We just have to keep looking.”
The quality of scientific evidence hinges, among other things, on the possibility of finding something false. Scientific theories that have been repeatedly subjected to crucial tests and survived have earned the status of being proven beyond a reasonable doubt. Those that have not been subjected to crucial tests, like macroevolution, have not been proven beyond a reasonable doubt. This suggests that people can reasonably reject macroevolutionary explanations for the origins of humanity.