Major transitions in the history of life

Published on March 31, 2016   26 min

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NEIL BLACKSTONE: The title of this lecture is "Major Transitions in the History of Life", and I am Neil Blackstone at Northern Illinois University.
When we think of the vast sweep of geological time and the massive changes that life on Earth and Earth itself have undergone, it seems impossible that anything about the history of life could exhibit a simple repeating pattern. Yet as remarkable as this may seem, it may also be the case.
Indeed, the history of life consists of a series of major transitions in which lower-level biological units cooperatively banded together to form higher-level biological units. First groups of molecules, then molecules within simple cells, then simple cells within complex cells, complex cells within multicellular organisms, and even in some cases, multicellular organisms within societies. In the process of these transitions, life became increasingly complex. While there is the simplicity in the repeating pattern, these major transitions themselves were not necessarily simple. In fact, they were perhaps the greatest achievements of organic evolution. In each case, the major obstacle impeding the transition was evolutionary conflict. As lower-level units band together, conflicts arise. Some units free ride using group resources without contributing their fair share. These conflicts must be mediated if a higher-level unit is to emerge.

Major transitions in the history of life

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