March 25, 2014 by kittynh
Thank you Claus Larsen for this review of episode 2. Claus will be reviewing each episode for Yankeeskeptic.
The second episode focuses on arguably one of the biggest scientific discoveries of all time, evolution. Despite the overwhelming scientific evidence in favor of evolution, the subject continues to be highly controversial, in particular in the United States, where biblical literalism reigns as the dominant worldview. How to explain this, to a population that predominantly thinks the entire universe is 6-10,000 years old?
Cosmos 2014 sticks to its goal, education: Uncompromising, but not confrontational. There is no ridiculing, no snark, only a powerful compelling presentation of the evidence.
The host, Neil deGrasse Tyson, kicks off by explaining how dogs came to be: Those wolves less afraid of humans gained many advantages, by letting humans domesticate them: A steady supply of food, stronger offspring, a much more secure life. In return, humans got a sanitation squad, trackers for hunting, an effective warning system, a strong line of defense, and, of course, great companionship. Through artificial selection, humans changed wolves to dogs, as well as other domesticated animals and plant produce.
Tyson then moves to natural selection, exemplified by the brown bear, adapting to the colder climate during the Ice Ages. With stunning computer graphics, we see why this can happen: The DNA of the brown bear, mutating by chance, enabling the offspring with an increasingly lighter fur to survive better in an environment covered in snow and ice.
Until now, and I suspect it will continue throughout the series, Tyson has maintained that science does not merely give us an explanation of the Universe, it also instils in us a sense of wonder and awe, even to the point of spirituality:
“If life has a sanctuary, it’s here, in the nucleus, which contains our DNA, the ancient scripture of our genetic code. And it’s written in a language that all life can read.”
The question why evolution has not been widely accepted is addressed in an understanding way: Humans are embarrassed by the looks and behavior of our nearest relative, the chimpanzee. The belief that we are created separately makes us feel special. But Tyson then asks us how we feel about our kinship with the trees. Humans and trees can both metabolize sugar, because we have the same parts of DNA. The most basic parts of life are shared by all living things, because that’s what was sorted out, at a very early time in the history of life. The staggering number of beetles and bacteria reminds us that we have yet to discover most of the species living on our planet. And the viewer is but one tiny branch on the Tree of Life. Talk about wonder and awe!
Tyson then addresses the issue of Intelligent Design. As many has done before him, the human eye is chosen as an example of a highly complex construction, too complex for anyone else but God. The evolution of the eye, or rather, sight, is explained by using split-screen: On the left, we see the organisms, to the right, we see how they would have perceived light. The advantages of telling even minuscule amounts of light accumulated, over a very long time, into the formation of the eye construction that animals have today. Tyson then throws his ace on the table: Humans actually have a pretty poor eyesight, since those animals who made the transition to land, had to stick with eyes that evolved in water. We land animals can’t see things up close, or discern details in the dark, the way fish can. This is because evolution cannot start over, but only change existing structures.
This enables Tyson to state as unequivocally as can be: Evolution is a scientific fact, like gravity. And that is, in the words of our host,”a soaring, spiritual experience.”
The explanation moves from the exemplary to the sublime: Since evolution is blind, and cannot foresee catastrophic events, we are taken to the Halls of Extinction, where the broken branches of the tree of life are exhibited. Most species have died out in the fight for survival, but many perished in the five cataclysms in the past 500 million years. The worst marked the end of the Permian geologic period, where volcanic eruptions caused massive global fires, resulting in destructive climate changes, killing most species. It was now the time of dinosaurs, which reigned for almost 300 million years, before the next cataclysm wiped them out. It must be hard to reconcile a divine intelligent designer with the notion that life was close to being annihilated by natural disasters, not just once, but five times.
If, however, you still cling on to that notion, Tyson has the final counter-argument: Life turns out to be extremely resilient, it is just not humans who are the best “designed” for survival. One species that did survive, not just the five cataclysms, but has been in existence since the Cambrian period, the tardigrade, or the waterbear. These tiny animals form their own phylum, and can survive the most extreme conditions found not just on Earth, but also in space. Yet, we still share the most basic functions with this ultimate survivor.
Speaking of which, what about life outside Earth? Briefly, we journey into space, to travel to Titan, Saturn’s biggest moon, the only moon in our solar system to have an atmosphere. Despite the differences, we do find similarities. Evaporating lakes and seas turn to rain, making it, in theory, possible for some life to start and evolve. However, the liquid is methane and ethane, while the landscape and mountains are largely water, frozen rock solid, so life would be very different from Earth. We can imagine it, but to know, we will have to go there.
We round off episode 2 with our host addressing the limits of science, exemplified in the origin of life:
“Nobody knows how life got started. Most of the evidence from that time was destroyed, by impacts and erosion. Science works on the frontier between knowledge and ignorance, not afraid to admit what we don’t know. There’s no shame in that. The only shame is to pretend that we have all the answers. Maybe someone watching this will be the first to solve the mystery of how life on Earth began.”
Message understood, Mr. Tyson.