Have you ever wondered about the phrase "missing link"? This is the first
article I've read that does a good job of explaining the misunderstanding regarding
"missing link" fossils ... versus, say, "transitional forms". But even that phrase
causes problems - - because it implies that one population of extinct animal
"transitioned" into this other fossil form! Sometimes that slightly different
fossil comes from a different lineage, but shows perfectly what the common
ancestor or eventual descendant could have looked like!
âNot that âtransitional formâ is without its own problems. The phrase can sometimes inadvertently cast an evolutionary cousin as an ancestor through popular translation. But it at least highlights that the organism in question helps inform what paleontologists have identified as a major shift in lifeâs history.â
Some scientists are moving towards âIntermediate Formâ which has fewer implications that one creature led directly to another. Sometimes it is years before experts know enough to know whether a new fossil is on a direct lineage (ancestor or descendant) - - or actually belongs to a related lineage, but demonstrates what a plausible Intermediate Form would look like between one known fossil and another!
How many times have you read âLife is really a tree, not a chain.â Havenât you ever wondered âwhat difference does it makeâ?!
Well, here it is!:
âTo me, the idea of a âmissing linkâ implies a linear chain of one species evolving into another, evolving into another, and so on,â says Smithsonian Human Origins Program anthropologist Briana Pobiner. That isnât the pattern we see [in the random fossils we find]. Instead. . . :
Evolution âproduces a tree-like branching pattern with multiple descendants of an ancestor species existing at the same time, and sometimes even alongside that ancestor species.â
âPaleontologists often prefer the term . . . âIntermediate Form,â because [it] impl[ies] ⌠these species are parts of an ever-changing continuum. This isnât just a matter of splitting hairs; terminology shapes our ideas and the way dramatic changes in the course of life are interpreted. Before (and even after) Darwin, naturalists sometimes saw species as part of a ranked hierarchy in which newer forms were somehow better than what came before. âSloppy words lead to sloppy thinking,â as Pyenson says.â
âIn some sense, every species i[s] a[n] [Intermediate] Form from its ancestor because it retains many ancestral traits but has enough unique traits to be a separate species,â Pobiner says."
"And given that every species alive today has fossils related to its ancestry, thatâs a lot of [Intermediate] fossils. More often, Pobiner says, âpaleontologists often use this term when talking about larger anatomical or ecological shifts that occurred during the history of life.â
For the sake of avoiding confusion in the public mind - - donât think âmissing linkâ, and try to avoid âtransitional formsâ - - and focus on âIntermediate Fossilsâ. While it is rare to know for sure that one fossilized life form literally represents an earlier or later population of Transition - - all similar fossils are Intermediate!
**[Note on Edits - - to better drive the point home, some sentences quoted from the article were edited to more consistently use the terminology of Intermediate Forms and Fossils.]