Investigating the ‘cost of complexity’ and the evolution of higher organisms

Amongst people who do not fully understand evolutionary biology, there’s this big misconstrued concept that human evolution has slowed down or even that humans have stopped evolving. If you don’t believe me check out the following links which are in chronological order from 1992 to 2006.

  1. Has Human Evolution Ended?
  2. Is human evolution finally over?
  3. Are we still evolving?

Some think that evolution has stopped because humans, and other higher organisms, are so complex, that the shear number pleiotropic interactions impedes on the rate evolution change. In a new Nature paper, Günter Wagner and crew have studied pleiotropy in mice. They investigated the quantitative trait loci (QTLs) that affect skeletal characters. They conclude that,

“most QTLs affect a relatively small subset of traits and that a substitution at a QTL has an effect on each trait that increases with the total number of traits affected. This suggests that evolution of higher organisms does not suffer a ‘cost of complexity’ because most mutations affect few traits and the size of the effects does not decrease with pleiotropy.”

Here’s the title and link to the paper, “Pleiotropic scaling of gene effects and the ‘cost of complexity’.” This paper is not only significant in clearing up this misunderstanding, but also enlightening in showing us how mutations simultaneously affect multiple phenotypic characters.

    Wagner, G.P., Kenney-Hunt, J.P., Pavlicev, M., Peck, J.R., Waxman, D., Cheverud, J.M. (2008). Pleiotropic scaling of gene effects and the ‘cost of complexity’. Nature, 452(7186), 470-472. DOI: 10.1038/nature06756

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