Evidence for Evolution!

The reason for focusing on this subject, is because there is much debate on this topic all over the internet all the time. And so, I want to show you guys some of the evidence, irrefutable evidence, of evolution.

What is evolution? 

Evolution is descent with modification from preexisting species: cumulative inherited change in a population of organisms through time leading to the appearance of new forms: the process by which new species or populations of living things develop from preexisting forms through successive generations. Natural selection is a key mechanism of evolution. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success.

--

The fossil record:

You may be familiar with archeology and maybe paleontology which study fossils. We all have seen the bones of a dinosaur or shells and ancient species in a museum or TV. Although these species do not exist, we recognize that they once did, because their remains were found. 

In just the same manner these scientists have discovered fossils that show us who our ancestors were. They show those intermediate fossils that prove that we are all related and that we evolved from a common ancestor. From fossils we can understand ecological relationships also, growth and behavior.

Transitional record:

A transitional fossil is an intermediate of an ancestral species and its descendants. 

One example of such transitional fossils is Pakicetus. Pakecetus is the ancestor of whales. How can we show that such is the case? We if evolution is correct, we would expect to find transitional fossils showing the connection between them. 

And indeed, that is what we find. Aetiocetus, which lived around 25 million years ago is that intermediate species that connects Pakicetus and Eschrichtius robustus (or the grey whale). We see, that Pakecitus has nostrils in the front of their skull, much like sheep, but in Aetiocetus we start to see that transition. Their nostrils are in the middle of the skull. Then in the modern whale we see them in the back of their skull.

Cellular evidence (homology):

If we look into the DNA and RNA of species, we can find similarities between all species. This is called homology. The fact that we all share similarities in our DNA is not surprising. After all, we expect there to be similarities in the cellular level, showing that we are indeed all related. For example, the genome of humans and chimpanzees differ by a small percentage. 

We can also see these homologies in the anatomy of different species. For example, whales and hummingbirds, different externally but with similar bone structures. This is due to them being descended from tetrapods. A tetrapod is a four-limbed vertebrate.

Embryology:

During the stage when embryos are still developing, we can see some show features of their distant ancestors. I find this to be a marvelous fact about nature. One example of this can be seen in baleen whale fetuses. We see that these whales have teeth, but only early in their fetal stage. They lose them before being born. This shows us that they have a common ancestor with toothed whales. 

Chromosomal evidence:

I think that this is one of the most surprising pieces of evidence for evolution. It's undeniable and also very interesting. The reason is because, if we expect there to be "plain" evidence for evolution, then we should look at the genetic code of all living beings. By looking at the genetic codes of humans and chimpanzees we can see such evidence. 

When we compare our chromosomes and those of chimpanzees, gorilla, and orangutans, we see how similar they are. What we also see is our evolution from a common ancestor. Humans have 46 chromosomes, while the chimpanzees, gorilla and orangutans have 48. 

What we see is that chromosome 2, in humans, has merged from two ancestral chromosomes and one of the two original centromeres has been inactivated.

Conclusion:

While this is in no way a complete list of the scientific evidence for evolution, I wanted to show that there is a solid foundation for it. I shared this couple of evidence to encourage you guys to look into it and find how amazing this subject is. Checkout my YouTube channel right here: @PhilosophicalMatter.