The concept of a Missing Link is sometimes bandied about by evolution deniers who think they have just upended the entire biology field.
The term has grown antiquated even among Young Earth Creationists since changes in biological populations over time can be observed in a Petri dish or even in nature, such as when a Florida lizard developed a toe pad that enabled the reptile to climb trees and escape predators. With evolution literally being seen in these instances, its authenticity is obvious to all but the most hardened deniers. The ad hoc response of most YECs is to create artificial categories of micro- and macro-evolution. To them, the toe pad addition is acceptable, but they reject evidence showing that the lizard’s deep ancestor was a Carboniferous amphibian and they insist that its descendant millions of generations from now could be something other than a lizard.
But the Missing Link term still makes infrequent appearances, so consider this a guide to delivering a handy retort. When someone uses the phrase, they ostensibly are referring to a supposed gap in the fossil record. Their supposition is that there are a series of transitions observable in the geologic column in which a group of populations become primate-like and continue to evolve. But there is a supposed gap from the likes of a gorilla to, say, Neanderthals. Proponents insist that since the record shows no in-between species that perhaps walks upright and sports opposable digits but has a lower IQ than your xenophobic great uncle dooms the concept of humans having evolved from a lower animal.
This, of course, gets evolution completely wrong. There is no neat, orderly, easily-identifiable path from single-cell organisms to all the members of today’s diverse Animal Kingdom. As populations split from their parent population, they disperse and adapt to their environment. Some die out and genetic drift impacts the process. Some populations continue to evolve because of their surroundings, while others like sharks hold steady since their biologic characteristics are sufficient for their surroundings.
Despite what some excited evangelicals Tweet, evolution does not teach that one species leads directly to another, such as a monkey giving birth to a human. Rather, the process is gradual, sometimes relatively quick and sometimes over 100 million years. Paleontologists do not expect to find a man-ape hybrid. They, were however, expecting that they might find a fossil of a species that lived before amphibians evolved but after fish did. That’s how they unearthed Tiktaalik. Like fish, Tiktaalik possessed fins and scales, but it also had a neck, a flat skull, and strong ribs. Tiktaalik filled the gap between previously known tetrapod-like fish and the earliest tetrapods. It is an in-between animal for fish and land animals.
While the Missing Link is a mistaken concept, an authentic notion is transitional morphologies, a term scientists use to describe discoveries that contain the anatomical features of both older and more recent species. This is the case with Tiktaalik.
Similarly, Live Science noted that humans share a common ancestor with some primates, such as the African ape. Hominids include people, chimps, and gorillas, as well as extinct ancestors, while hominins include those species after the human lineage split from chimpanzees. Much as I would like so support all this with a URL, that link is missing.