They just don’t call it that:
Two surprising analyses that appeared in Nature Ecology & Evolution early this year have hammered home just how inessential genes can be, and how creatively evolution can deal with losing them. By analyzing hundreds of genomes from across the animal kingdom, researchers in Spain and the United Kingdom showed that a startling degree of gene loss pervades the tree of life.
Their results suggest that even early animals had relatively complex genomes because of an unprecedented spurt of gene duplication early in life’s history. Later, as lineages of animals evolved into different phyla with distinct body plans, many of their genes began to disappear, and gene loss continued to be a major factor in evolution thereafter. In fact, the loss of genes seems to have helped many groups of organisms split away from their ancestors and triumph over new environmental challenges.Vivian Callier, “By Losing Genes, Life Often Evolved More Complexity” at Quanta
The thesis of Darwin Devolves is that most adaptation/evolution is due to loss of genes (devolution). The Quanta article seems to agree that loss of genes is a major means of the development of life.
Funny how those early organisms acquired all those genes so quickly, as opposed to the long, slow process of evolution we’ve been led to assume.