Transcript
Evidence of Evolution: Homology
Film: There is the front flipper, a hand built on the same model as my own hand.
Meyer: Biologists define homology as similarity in structure between different
organisms.
Film: and this has the same design exactly as your arm.
Dehart: My textbook would show the forelimb, a hand, a bat’s wing, and a whale’s
flipper. And say because they have a similar structure, a similar bone pattern, they must
share a similar ancestry.
Film: And five very long fingers, just like yours.
Nelson: Homology was something that biologists discovered long before Darwin.
Aristotle taught homology. The real question about homology is how do we explain it?
Berlinski: There are plenty of examples of homological structures in biology, which are
obviously not based on common decent. Take for example the Australian wolf, which
except for the reproductive system features a wide variety organ systems, which are
absolutely homological to the North American timber wolf. But there is no evidence
these homological structures arose because some wolf some time in the past, or some
proto-wolf decided first to migrate to Australia and then to migrate to North America.
The evolutionary lines are completely distinct. And yet we see a profound degree of
homology. We see this throughout the animal kingdom.
Wells: The mirror pattern of the bones doesn’t tell you how it happened. You have to
supply a mechanism to explain how it got that way. Well, Darwin’s mechanism as
understood by Darwinists is genetic. You inherited similar genes, these genes made
bones grow the way they do. The problem is that the evidence doesn’t fit that
explanation.
Narrator: According to modern Darwinism, if 2 structures are similar because of
common ancestry, each structure should be produced by similar genes and go through a
similar pattern of development in the embryo. But, contrary to these predictions,
biologists are learning that homologous structures can be produced by different genes and
follow different patterns of development. For example, biologists consider the body
segments of fruit flies and wasps as homologous. Darwinism predicts that these
similarities should be produced by the same gene. But in fact, different genes account for
the development of body segments in these insects. This contradicts the idea that
homology must point to common ancestry. In the same way many body structures
considered homologous by biologists develop in embryos in fundamentally different
ways. One example is the gut in vertebrates.
Nelson: If Darwinian theory were correct, the process by which the gut is constructed
should itself be homologous. In fact, this is not the case. We know for instance that in
different vertebrates the gut is constructed very different ways during development.
Narrator: In sharks the gut develops from cells in the roof of the embryonic cavity. In
lampreys the gut develops from cells on the floor of the embryonic cavity. And in frogs,
the gut develops from cells in both the roof and the floor.
Nelson: So you have a homologous structure in vertebrates that are built one way in the
shark, one way in the lamprey, another way in frogs. You have got very different
developmental pathways converging to the same structure. This is very hard to reconcile
with Darwinian common decent.
Film: These marine reptiles were built on much the same plan as you are.
Nelson: I would say that the past 23 years of studying this problem that biology is now
entering what can only be described as a revolution, because the evidence is so
overwhelmingly against the conventional neo-Darwinian view.
Film: Now what about those other reptiles that flew in the air.