Evolutionary Musings

[Johnathan Clayborn]
Based on all of the new information I have learned about the plethora of member species with the genus Homo and the genus Australopithecus I have been wracking my brain with all kinds of questions about evolution and humanity.

Clearly, in my mind, the mountain of data and fossils that they have uncovered seem to soundly refute the notion of intelligent design as even being a possibility. A glance at comparison photos of known hominid skulls speaks more to this than I can ever do with words: http://jisciences.blogspot.com/2010/01/human-evolution-101.html. The resemblance between several of these skulls as compared to modern humans (bottom right) is astounding.

But, of course, having stated that I do not believe that intelligent design is the answer is not the same thing as saying that I believe that scientists have the right answer either. Clearly, they’re still trying to figure it out as well. Much of the evidence that I’ve seen leads me to believe that they are on the right track, however, it also makes me wonder how long it will take before we fully understand and ancient family tree, if that day ever comes to pass.

The first thing that should be pointed out to continue this discussion intelligently is to consider the entire mountain of research that has been completed with regards to the Human Genome Project. The entire human DNA genome was sequenced and decoded. Many hundreds of studies have been done on the DNA of modern humans and we now more about ourselves than ever have before.

In fact, by studying the different genetic mutations of the human hapologroups scientists have been able to recreate the historical migratory pattern of our human ancestors for tens of thousands of years. Maps such as this one: http://www.kerchner.com/images/dna/ydna_migrationmap_(FTDNA2006).jpg and this one: http://www.roperld.com/graphics/MigrationMap.jpg. One interesting thing about these DNA studies is that they seem to loosely confirm some of the biblical concepts found in Genesis; every living person on Earth is descended from one common male ancestor and one common female ancestor. The only scientific hitch is that these individuals did not live at the same time.

All of this type of information, dating back to around 200,000 years ago, is a relatively small amount of time on the time-scale of human evolution. Scientists had believed that they had found a generalized “tree” of evolution that showed that humans descended from Neanderthals, and that if you go far enough back there was a common ancestor that tied everything neatly together. Many, many times this concept has been referenced within popular culture. The Geico commercials featuring the “cavemen” is one such example, as are movies like “iceman” and “homo erectus” and even an episode of Star Trek: The Next Generation entitled Genesis where the crew de-evolves into more primitive species. Commander Riker turns into a Neanderthal.

Now, this is one point where I want to stop and explain one surprising counter-argument that I’ve found against evolution. There was one particular blog post I was reading a few days ago where the gentleman who wrote the blog was essentially saying that evolution is wrong because it’s racist and that it was only intended to prove that Africans and other non-white peoples were primitive and stupid, and then worthy of enslavement and mistreatment. Naturally, I had to set the record straight. In terms of evolutionary biology the word “primitive” does not mean “stupid or unintelligent”, it means “most like the original specimen.  As one example, suppose that you were to look at all of the different models of cell phones that exist today. Some a flip-phones, some are touch-screens, some are smart phones, some so-called “candy bar phones”. But, if you look at all of the different models of phones and their styles and functions there are many traits and characteristics that they have in common. But there is one trait or feature that all cell phones share; a number keypad; thus logically we can deduce that if all phones have a numbered keypad, then that is something that that must have come from the original model of cell phone since it is a trait that is present on its modern day descendants. Scientists refer to this “common denominator trait” as the primitive trait (as opposed to the advanced trait, which is the result of the process of evolution).

Putting that analogy to application in the evolutionary sense, “eyebrow ridges” (aka; supraorbital torus) is a trait that is found in every species of the genus Homo, Australopithecus, Pan, and Gorillini. Based on this, scientists have concluded that eyebrow ridges are a primitive trait, one that our common ancestor had as well. Based on genetic sequencing of fossil remains, scientists also believe that fair skin is a primitive trait and that darker colored skin is a more advanced trait; an evolutionary defense mechanism that people developed to protect themselves against the sun.  This particular topic, and this word in and of itself is one that is misunderstood and has been the cause of many debates over and over. For the record; scientists no longer believe that we are descended from Neanderthals, but instead that they were a sister species. They also do not believe that the Neanderthals were unintelligent. There is evidence to support that Neanderthals made tools, used projectile weapons, had language and some researchers even postulate that they may have developed art and music. In fact scientists now believe that one of the hominid ancestors, Homo Erectus sailed the ocean on rafts more than 700,000 years ago. When a scientist is calling a species primitive it is not in regards to its intelligence. Even modern day Gorillas and Chimpanzees can be taught to speak in sign language and understand human language, even if they are not able to reproduce those sounds. Clearly this is a sign of intelligence as well.

There have been a lot of changes in the concept of human evolution recently. Much of it is the result of new fossils that have been found within the last 10 years. Take, for example, this fossil found only two years ago: http://www.foxnews.com/scitech/2010/03/24/new-ancestor-scientists-ponder-dna-siberia/ or this one found in 2007: http://news.softpedia.com/news/New-African-Fossils-Further-Complicate-Human-Evolution-62257.shtml. Many opponents of evolution will cite these are arguments that these finds disprove evolution. I would disagree with them. Evolution has been proven as a concept as far as I am concerned. You want examples? Look at the donkey, a cross-breed between a mule and a horse. Take modern almonds as another example; the historically ancient version was poisonous to human consumption. And what about modern corn? It’s more than 3 times as large as its ancient ancestors with larger kernels.  The fact that there is so much ambiguity and confusion about the process of human evolution just means that we don’t have all of the answers. Look at the how many times we’ve been wrong before; the world was flat, the sun revolved around the earth, reflex was the result of an internal hydraulic pressure system, etc. Whenever you are trying to piece together a puzzle and old and as complex as this one you are bound to run into instances where the pieces don’t quite fit just right, even though it looks like it belongs there. This process is no different. As evidence that evolution is not only possible, but probable, consider this naturally occurring hybrid shark found off of Australia a few months ago: http://news.discovery.com/animals/hybrid-shark-australia-climate-change-120103.html.

But, even understanding that there are some margins of trial and error there are many questions that I have about humanity and evolution. One such example is the consideration given to the competing theories on human evolution. One of the most popular and widely accepted theories is that Humans (Homo Sapiens Sapiens specifically) migrated out of Africa and colonized the rest of the planet starting at around 150,000 years ago. This is called the Recent African Origin theory (RAO). The biggest evidence supporting this theory as being correct is the many hundreds of thousands of DNA studies conducted during the Human Genome Project (the maps I posted earlier). This is regarded as fact; humans did migrate out of Africa, no one is disputing that claim. But is this the only possible explanation?

The main competing explanation of the Recent African Origin Theory (also called the Recent Single-Origin Hypothesis (RSOH)) is the so-called Multiregional Origin Hypothesis. This model states that the human beings are different all over the world because they are all one species that diversified to fit their environment and that these “ancient bones” are all also human and just other examples of this diversification. Their primary arguments center around the fact that Homo Erectus is found in both Asia and Africa at the same time and that Homo Ergaster is physiologically similar to Homo Erectus to the point that some experts believe them to be the same species.

Pragmatically, there are issues with both of these theories. With regards to the multi-region theory, if all of these fossils are the diversification of a single species, then where did that species come from? This particular theory is most-often posited by those who favor intelligent design. But, on the other hand, if the RSOH is correct, then where did all of the other species of Homo go?  If they are so genetically close to us, why did they die off and we survive?

These questions lead me to profound questions of my own. It has been pointed out numerous times that the overall skeletal morphometry of modern humans is wildly diverse. It’s also been pointed out that some modern humans have physiological characteristics in common with these ancient bones. Therefore, one question that comes up is did the ancient Early Human Ancestors (formerly known as “cave men”) interbreed with the other species of Homo during the last few hundred thousand years and is there evidence of that today? The results seem to indicate that this is likely true. Some studies have shown that some middle eastern DNA sequences have between 4-8% DNA genome in common with Homo Neanderthalensis. This is suggestive of interbreeding.  It’s also been pointed out that the skulls of Malaysians, some Asians, and Aborigine Australians (among others) have many physical traits in common with Homo Erectus, such as the prominent supraorbital torus, and the sloping forehead.  There have been some studies that seem to support this (http://ethesis.nitrkl.ac.in/2406/1/brijeshthesis.pdf, http://unsw.academia.edu/StephenWroe/Papers/1527145/Human_remains_from_the_Pleistocene-Holocene_transition_of_southwest_China_suggest_a_complex_evolutionary_history_for_East_Asians) however, the data and the studies that have been done on non-Africans and non-Europeans have been very limited. Thus, it begs the question; are those humans examples of cross-breeding between Homo Sapiens Sapiens and Homo Erectus, or are those humans modern day living examples of actual Homo Erectus specimens? The studies conclusively show that modern human skull characteristics differ considerably across the globe. This further begs the question; are these morphometric variances within tolerance for a shared taxonomic classification as evidenced by scientific standards, or should the variances be broken down into different taxonomic classifications? And does the entire genus Pan deserve to be moved within the genus Homo based on the close genetic kinship? There is a precedence for such an action based on prior DNA comparisons of other non-human species. And if that happens then would chimps then be considered “human”? Paleoarchelogists have determined that many species of early hominids used fire, tools and had developed language and some of them they theorize had art. Many of them lived in social settings much like we do. Thus, I can’t help but wonder, what does it mean to be “human” and where does one draw the proverbial line in sand between “human” and “nonhuman”? As you reflect on that question go take a look at the reconstructions of the fossils found here; http://www.daynes.com/en/reconstructions.php and really ponder what it means to be human.