Beyond our naked eyes

Abstract

Transposable elements in bacteria are short segments of DNA – composed of hundreds to thousands of nucleotides, that behave like small fairytale elfins who are always willing to relocate. Those small elements, having evolved for billions of years, are so successful that they occupy an extremely large proportion of genomes of living organisms, for example up to 50% of the human genome. In his recent book, Evolution: A View from the 21st Century, James Shapiro, a well-known expert of transposable elements at the University of Chicago, not only shares stories about transposable elements, but also tells readers about how his new evolutionary theory explains different molecular processes in cells and living organisms. It is a highly traditional subject that Shapiro had to lay out in the book, but what he revealed is so fascinating that I could not stop thinking. He tells us how cells chat with each other, how cells decide when they duplicate themselves, and how bacteria find foods and partners. He also tells us, how living organisms, like humans, make decisions based on their own interests, benefits, costs and risks. The molecular mechanisms behind these complex activities, as well as the structure of genomes of living organisms may have remained secret from the humans. However, thanks to the advances of molecular biology technologies, they have now started to be revealed. After reviewing the progress in molecular genetics and genomics, Shapiro proposes a new concept of natural genetic engineering denoting the ability or capacity of organisms to modify their own genomes, as a basic feature of evolution. Through his novel evolutionary theory, we can understand how genome structure evolves to adapt to a new environment. Notably, Shapiro not only completely abandons the neutral evolution theory, but also demonstrates that Darwin is wrong. This could be a very exciting progress in the development of evolutionary theories, but some of his major conclusions are still controversial. For example, his statement of “selection has never led to formation of a new species” appears to contradict the molecular evidences recently found in humans, Drosophila, plants and other species. In the last decades, scientists accumulated large amounts of evidence about evolution, and coined thousands of scientific terms that may sound cryptic to nonprofessional readers. In the book, Shapiro avoids using opaque and confusing words, so that a layman has no problem following his reasoning and Shapiro’s excellent writing and story-telling skills make the book very entertaining. For readers who want to go further, the book always provides extra links to external materials when they feel necessary to dig into a specific subject. These external materials will be especially handy to help readers to assess Shapiro’s novel insights into biological functions. For example, in population genetics, the (random) alterations of genome structure due to natural genetic engineering are known as mutations. As soon as a mutation emerges from a population, its fate is determined jointly by the environment and a random process called