In three previous posts (this was the latest), I wrote more or less the following words:
The
scientific theory of evolution is strongly supported by data from other
sciences, such as embryology, comparative anatomy, paleontology, biogeography,
and molecular biology (DNA analysis).
Since, despite everything, there are still those who doubt the scientific nature of this theory, in this post I will expand on the previous paragraph, explaining in a little more detail the scientific data that favor evolution.
1.
Data based on embryology: Shortly after Darwin proposed his theory of
evolution based on natural selection, one of his followers (the German
naturalist and philosopher Ernest Haeckel) formulated the theory of recapitulation, which can be expressed as follows: ontogeny
recapitulates phylogeny.
The word ontogeny means the development of a living being throughout
its life. The word phylogeny means the evolutionary history of its species.
Today, Haeckel’s theory is rejected as overly simplistic, but it is accepted in
a modified form, as Wikipedia
says: Modern biology recognizes numerous connections between ontogeny
and phylogeny, but explains them on the basis of the theory of evolution,
without resorting to Haeckel’s views, and considers those connections as
evidence for [the] theory [of evolution]. Among classic arguments is the fact that mammalian embryos go through a stage in which they have gill
arches like those of fish, which later disappear, and notochords, like those of
the ancestors of vertebrates, which immediately transform into the vertebral
column. Or whales, which during their embryonic development have legs and tooth
germs, which are later reabsorbed. Plus many others.
 |
| Richard Owen |
2.
Data based on comparative anatomy: Richard Owen, a contemporary of Darwin,
distinguished between analogous and homologous organs. Analogous organs are those whose origin is
different, but which, having the same function, have evolved to acquire the
same form (see this
recent post). For example, the fins of fish, those of the swimming reptiles
of the Mesozoic, and those of cetaceans are analogous. Homologous organs are
those that have the same origin, but which evolution has led to have very
different functions, and therefore very different shape. For example, our arms,
the forelimbs of quadrupeds, the paired flippers of cetaceans, the wings of
birds, those of bats, and those of flying reptiles from the Mesozoic are all
homologous. The existence of analogous, homologous and atrophied organs is a strong
argument in favor of the theory of evolution.
3.
Data based on paleontology: Since the 19th century, when this science began
to develop thanks to the discovery of many fossils, several evolutionary chains
have been detected, indicating the existence of fossil lines that evolved over
time in a specific direction. One of these lines followed the evolution of
equine legs during the Tertiary Period, beginning with species with four toes (Eohippus and Orohippus), with three toes (Mesohippus, Miohippus, and Hyohippus), with one main toe and two vestigial toes (Neohipparion), and with a single toe (Pliohippus and Equus, the latter being modern horses). Although today
it is thought that evolution did not occur linearly, because it branched out many
times, in the century and a half since then, the discovery of new fossils has
filled in the gaps and given support to the theory of evolution. Many of these
discoveries can be considered validations of the theory, because they had been
anticipated.
4.
Data based on biogeography: This science, which studies the geographical
distribution of different species of living beings, provides important support,
not just for the theory of evolution, but also for geology, by making it
possible to infer the shapes taken by continents in past times. For example,
the group of lungfish called dipnoans is composed of three families, each of which
exists only in one part of the world: the Ceratodontidae in Australia; the Lepidosirenidae in South America; and the Protopteridae in Africa. The three families have evidently a
common evolutionary origin, and their presence in these three biogeographic
regions is evidence in favor of the theory that Africa, South America, and
Australia (in addition to Antarctica and India) formed a single supercontinent
hundreds of millions of years ago, which has been named Gondwana. The differences between the three families are an
indication that they have evolved from common ancestors after the continents
separated. There are a lot of data of this kind, but this is not the place to
list them all.
5.
Data based on molecular biology: This is the most recent science that has provided
data in support of the theory of evolution. The analysis of the DNA of various
living species and the comparison of their genomes has made it possible to build
a version of the
tree of life based not on visual comparisons of animal groups, but on their
DNA, to determine which species are related to each other and which are not.
The combination of this with the data provided by the aforementioned sciences adds
up to an overwhelming body of evidence in support of the theory of evolution,
which no serious scientist now questions.
Of course, many mysteries remain unsolved in the
current form of the theory of evolution. This is true in all branches of
knowledge. Despite the accumulation of scientific knowledge, each new discovery
opens up new fields and introduces previously unforeseen unknowns, making
scientific research a never-ending process. In a
previous post, I listed some of these mysteries.
In the next post I’ll answer a few arguments usually alleged against the theory of evolution by some people who are not expert biologists.
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