A new study confirms Stephen Jay Gould’s theory saying that evolution doesn’t mean just continuously adding features to organisms.
The evolutionary biologist Stephen Jay Gould published in 1996 the book Full House. The author compared evolution with the walk of a drunkard leaving a pub and going to the rails of a train station. Involution also played an essential role.
The metaphor works like this: the drunkard is the live organism, the pub is involution (losing genes and getting to a simpler branch of reduced complexity), and the rails are the evolution (adding genes and getting to a complex level). There is no train in the metaphor so don’t wait for it.
When interpreting the metaphor, one must understand that what we call evolution had a very different way of becoming than what we imagine. And our imagination has been highly influenced by the famous picture of monkeys turning into humans. Highly and wrongfully.
Evolution would have been nothing without involution
Evolution didn’t happen coherently nor progressively. Evolution is the drunkard going back and forth. Losing and achieving complexity according to the environment and the organism’s needs. So, evolution and involution go hand-in-hand.
Recent research took Gould’s theory to the next level. Wanting to study how the animal kingdom has evolved at the genetic level, it compared the complete genomes of over 100 organisms, mostly animals. And the results sustain Gould’s idea that evolution doesn’t always result in increased complexity, but also in the loss of it. Going simpler also helped to evolve.
Evolutionary lineages are linked not to the addition of new genes but to massive gene losses. An evolutionary lineage is a temporal series of populations, organisms, cells, or genes connected by a continuous line of descent from ancestor to descendant. Lineages are subsets of the evolutionary tree of life. Humans, for example, are deuterostomes, which include other vertebrates, as well as sea stars or sea urchins.
The novelty is that by studying the genomes of different organisms, researchers discovered that genes were also lost in the evolution process, not just added.