Evidence for evolution
Here’s some of the evidence available for evolution:
1. Fossil record: The fossil record is the piece of classical evidence that is always given for evolution. Paleontologists digging at various sites across the world have always found the long preserved remains of exotic and mysterious creatures that clearly do not exist today. The important part is not what is so different from today, but the striking similarities they hold to current life. If we track the fossils in order of age, we find an interesting trend. As we get closer and closer to the modern day, the fossils we find become more and more similar to modern creatures and more and more complex. As we go back in ages, the differences between species that appear greatly different become more and more blurred. What does this mean? It suggests that there is some mechanism for a trend of gradual increasing complexity in life and in the beginning, some sort of common ancestor, precisely what is predicted by evolution. We can trace the trend in evolution not just with fossils but also with evidence like stored ice cores way past the birds and fish of creationism to see how they developed. Not only this but we do get some transitional forms, species that appear “half evolved”.
2. Interspecies variation: If we look at life today across the spectrum, we see a combination of difference and unexpected similarities. Humans appear very different from, say, mice, but in fact the latest studies show that over 90% of the genomes are exactly the same. If we look at the parts that are the same and the parts that are different, we find that the same parts are the ones that are successful and fundamental to life, accounting for characteristics that appeared longest ago. Meanwhile, the more different parts code for characteristics that allow each species to adapt to their own niches. What doesn’t need changing doesn’t change across species. This fundamentally same yet different state across life suggests that each was not created separately but developed from a common ancestor. If we factor in geography into this, we can see that certain species are concentrated in certain parts of the world, and there is generally a clear distribution of characteristics from place to place. This suggests evolutionary adaptation at work.
3. Unnecessary features: It is a little known fact that large parts of the human body are surplus to requirements. The appendix, for example, serves no practical use in man, and often causes problems necessitating removal. Body hair is almost completely useless given clothing, and even is a hindrance to cleanliness. A number of major religions have noticed the uselessness of foreskin. This is not just true for humans – horses for example have vestigial side splints on each of their hooves. The best explanation for these useless features is that they are remnants of organs once useful, but no longer, in the process of being reduced away by evolution. For example, if we look at the appendices in herbivores, we can see they serve an important part in digesting difficult, fibrous matter. We can thus deduce that some long ancestor of man was an herbivore, but since then changes in human diet and environment rendered the organ pointless.
4. Current evolution: Today, we do see evolution happening right now. The best example is the case of bacteria gaining resistance. New bacteria like MRSA quickly mutate and gain resistance to antibiotics. This is an example of evolution in action. It follows that if evolution happens now, it is only logical it happens before and in the future. Over millions of years, minor changes inevitably merge as large general trends in evolution. Selective breeding is another example. Dogs are greatly different from wolves, but evolution with man providing the selective pressure accounts for its creation.
5. Logical evolution: One of the great strengths behind the process of evolution is that it MUST happen. If you ever have some opportunity for random chance, some system for hereditary features and some form of selection, evolution will happen. One is a logical consequence of another. It is not surprising that change occurs, but it would be surprising if change does not. Computer programs have been written to simulate this. Indeed, one of the ideas for the next generation of artificial intelligences is not to program them but to allow them to program themselves, in a process of evolution. It is easy to show mutation (just think of cancer), heredity (look at family similarities) and natural selection (bigger animals do better than smaller ones) occurs, so evolution must occur in some shape or form.
I have a BS in Information Sciences from UW-Milwaukee. I’ve helped manage Physics Forums for over 17 years. I enjoy learning and discussing new science developments. STEM communication and policy are big interests as well. I have a lovely wife and a cat named Mason.