It is hard to find a scientific idea more thoroughly proven than the theory of evolution.
Evolution is one of my favorite topics. I love exploring anatomical, physiological, mental, and genetic changes for which we have striking fossil and genetic evidence. We have uncovered much over the past century, not just about the physical and intellectual changes in hominids over the past 7 million years, but also about the climate conditions that helped give rise to these changes.
Following the fossil record leads us to a profound insight about the migration of a species called Heidelbergensis from Africa to Europe about a half million years ago. The gradual physical and intellectual changes European Heidelbergensis experienced led to changes that gave rise to a new species, Neanderthal (and Denisovan). Those Heidelbergensis stragglers who stayed in Africa became Homo Sapien Sapien, or modern humans.
We know, from genetic evidence, that humans got some of their genes from Neanderthal, and that interbreeding happened as late as 35,000 years ago. The encroachment of modern humans into Europe led, for a variety of reasons, to Neanderthal’s extinction.
However, the resulting gene transfer between Neanderthal and Humans probably contributed to better human adaptations to cold weather, and also provided immune system benefits
There’s an old-fashioned argument made by evolution deniers, making reference to the absence of a “missing link“.
I find Heidelbergensis to be the perfect response to this concern…then Neanderthal, Ergaster, Erectus, Habilis, etc. The enormous genetic and fossil evidence we see leaves no doubt about the gradual transitional changes that eventually gave rise to humans.
One of the things I’ve tried to understand is the motivation for the dogged denial, on the part of a pretty hefty percentage of this country. Clearly, the original sin issue is a pretty major deal, because once original sin is gone, so is salvation. Another obvious factor in the general ignorance about evolution is the fact that most people don’t understand or study evolution, and therefore, can dismiss it as science fiction.
The thing that concerns me about evolution denial is that it raises concerns about what other reasonable conclusions people might forego for the sake of their faith; that is, the political, social, and economic decisions they make.
For evolution deniers, I’ve tried to assemble a list of questions that might help them reconsider their point of view. In fact, if you’re reading this, and are an evolution denier, I’d be curious to read your responses to these questions.
1. How do you explain the fact that we saw dogs change, in temperament, skin thickness, the ability to produce amylase in their gut, and overall size, from wolves?
2. Given the difference between, say a Chihuahua and a Wolf, isn’t it even a little bit reasonable that small changes can add up over time to create bigger changes, if not genetically, then at least physically?
3. Considering the fact that we’re able to demonstrate, in the lab, microevolution of various cell types over a small period of time, and considering larger changes we’ve observed (ie wolves to dogs), why is macro evolution so unbelievable?
4. Do you reject the fact that there exists fossils of Neanderthals, Denisovans, and Heidelbergensis? What are your interpretations of what those early hominids were, if we can demonstrate that they were not human?
5. Does it seem to you that the skeletal differences between a Chihuahua and a Wolf might be at least as significant as the difference between a human and one of their forebearers, such as Heidelbergensis or Erectus?
6. Given some genetic mutations we observe today, such as Ectrodactyly (lobster-claw hand), Polydactyly (extra fingers), and Achondroplasia (dwarfism), doesn’t it seem plausible that some genetic condition, if favorable for a species, given the right environment and geographic isolation, might lead to significant changes between different groups of the same species?
7. Given the fact that we can investigate the genetic makeup of plants, animals, and people, combined with the fact that we can investigate the genetic makeup of a skeleton that has been dead for a very long time, how do you explain the fact that, as species look and act similarly, there is usually a genetic correlation between those species? For instance, the genetic difference between humans and chimps is less than 2% [http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html] and that bonobos and humans share about 98.7% of DNA? [http://news.sciencemag.org/plants-animals/2012/06/bonobos-join-chimps-closest-human-relatives]
8. To followup on #7, how do you explain that genetic analysis of Neanderthal reveals a 99.7% similarity with humans?
9. As you might know, living organisms have DNA. DNA gets converted into RNA, and then into protein inside cells with protein structures called ribosomes. DNA is packaged in genes, which make up chromosomes. How do you explain the fact that very different species have remarkably similar genes AND the fact that those genes do virtually the same thing in those very different species?
10. We do see similar genes making similar physical structures across species; we also occassionally see that different species have similar behaviors, but perform those behaviors with different genes. For instance, coffee and tea both make caffeine, but they do so with different genes . Isn’t it reasonable that the reason for this is because there were natural pressures that led both species, in different environments, to develop adaptations to behave in this manner?
11. One of the major genetic differences between humans and bacteria is the fact that human cells are Eukariotic, and bacteria cells are prokariotic. This means that human cells have mitochondria, which helps them produce energy; prokaryotic cells, such as bacteria, are absent of this feature. Recently, a study was released by the University of Virginia that hypothesized that many billions of years ago, some prokaryotes were parasites on other cells, and this relationship eventually became mutually beneficial for both the parasite and the host cell, leading to more complex life forms. What are your thoughts on this, and in particular, the relationship between the complexity of life and the presence or absence of mitochondria and cell membrane?
12. One of the techniques scientists use to determine the age of rocks is called radiometric dating, where the amount of remaining radioactive atoms are compared to the amount of by-product of radioactive decay. There are over a dozen radiometric dating techniques, relying on a variety of radioactive material and known observed decay rates. In radiometric dating, the current state of a rock is analyzed, including its remaining byproduct and the amount of remaining, non-decayed isotopes. These values are then fed into a logarithmic equation, and when coupled with the known half-life of a radioactive element, scientists can determine how old the rock is. Do you believe that all radiometric dating is faulty and unreliable?
13. One of the arguments for why the earth cannot be very young (ie less than 10,000 years old) is because, given the amount of known nuclear material underground, and our current observations about decay rates, along with associated heat that is released as that material decays, the implications would be that, on such a young earth, radioactive decay would need to occur much faster than we observe it today in order to give rise to our current geological profile (the current state of the physical earth). Given that we have been very unsuccessful in increasing radioactive decay rate, despite a large amount of attempts to do so, how do you explain why radioactive decay must have suddenly slowed down?
14. Aside from radiometric dating, scientists can analyze which soil strata fossils are found in to get a rough estimate of the age of the fossil. Why do you think that there is such consistency for particular species always occurring in particular soil strata? In other words, why don’t we find any modern mammal fossils in the Cambrian layers?