From your inner fish to the universe within

by Salman Hameed

Since we are coming fresh from the dialogue on evolution and Islam, I thought I'll stay with the topic of evolution. One of the best popular books on evolution is Your Inner Fish by Neil Shubin. He is also responsible for the discovery of the fossil of Tiktaalik - an example of animal transitioning from water to land (from fish to tertrapods), about 375 million years ago. If you haven't read the book, you should definitely check it out. The discovery of Tiktaalik is a fantastic example of good science: There was a specific prediction that geologic strata 380-365 millions years should contain examples of animals that may provide hints for fish to tertrapod transitions. I will let Neil Shubin explain this in this fantastic lecture:



Now, Shubin has a new book out that looks at the connection between the universe, our solar system, Earth's history and our own body: The Universe Within: Discovering the Common History of Rocks, Planets, and People. Here is an excerpt from the book's review from this week's Nature:

Shubin starts with the formation of the Universe 13.7 billion years ago, segueing into that of the Solar System 4.6 billion years ago. Much later, about 200 million years ago, when the supercontinent Pangaea broke up, the continents and ocean basins we know today began to form. This was accompanied by the rapid evolution of more complex life forms — dinosaurs, mammals and birds. 

Shubin suggests a rather original connection between continental break-up and the evolution of such creatures: mud settling on the vast stretches of coastline created by the break-up of Pangaea buried biological material that would otherwise have decayed in water, using up oxygen. The result, Shubin says, was an increase in atmospheric oxygen, one of the key factors that allowed animals to conquer land. Mammals require a lot of oxygen to maintain their high-energy, warm-blooded lifestyle. Life on the low-oxygen Earth of 200 million years ago would have been like that today at 4,500 metres above sea level. 

Much of the second half of The Universe Within summarizes the history of how our geological view of Earth developed. It incorporates stories such as how the discovery of similar fossil organisms on distant continents led Alfred Wegener and others towards the idea of continental drift. We also meet William Smith, who invented stratigraphy, Louis Agassiz, who discovered ice ages, and geologist Bruce Heezen and oceanographic cartographer Marie Tharp, who were central to developing the theory of plate tectonics. 

Shubin is at his best when he deals with anatomy and biology, as in his discussion of the inventive geologist Michel Siffre. In 1962, Siffre spent two months living in a subterranean cave to gauge whether he could track time without any tools with which to measure it. After two months, he was convinced that only 37 days had passed. This was in line with what we know about the role in 'internal clocks' of the pineal gland, which regulates the production of sleep-inducing melatonin depending on the available light. Shubin's storytelling in such passages is gripping.

Read the full review here (you may need subscription to access that).

Oh - and for your entertainment purposes, here is Titaalik - the song: