Answering an Evolution Question.

21 04 2011

Alright, so a brief explanation is in order. To answer the question :

“Why are there still apes and why didn’t they all “turn into” humans?”

The quick easy answer is evolution isn’t a large step process taking a species and splitting it into two groups, it all literally starts with 1 individual member of the species, or 2 if you count the mate that helps with making the baby, passing along their genes through a large number of generations until there are either multiple versions/species, or one new version/species that wipes out the population of the previous.

Evolution works through a process called natural selection where a species will change or adapt over long long periods of time. We are talking thousands and millions of years. Some changes are small and some are big. Depends on the factors involved like how it benefits the species and what other potential changes that benefit may cause more rapidly. All animals and life forms eventually trace back to a single life form, meaning that we are all related through some way. Not directly in almost all cases but through common ancestors which have split and split and split etc.

In evolution through natural selection you have 2 types of splits. You have a branching of a single species where two roads or paths will arise therefore giving us 2 distinct species, and there is the alteration split where A and B arise, A has a new feature that provides a better chance of having more offspring which will eventually wipe out B. This is the type of evolution you are referring to, the modification rather than splitting. We are actually the result of both forms in a way, but to answer your question, we split from our ancestor apes, and then had many modifications since which have all gone extinct since due to the pressures of natural selection. There were times where more than one species of homo were around together, and they indeed clashed on many occasions with each other. (and NO I don’t mean homo as in gay for anybody looking to take my words out of context, I’m referring to Homo as in the Genus which is the classification above species)

Take the 2 species Chimp’s and Bonobo’s for example. They are visually almost the same animals with small subtle differences, but major behavior differences. This is the kind of splitting we had with our common ancestor with Chimp’s and in fact this split between Chimp’s and Bonobo’s happened after our split. The common ancestor was an ape that was similar to both humans and chimps.

The history of humans has been a long line of the modification evolution after the split. You can picture a tree branch with twigs and other branches coming from it, each branch and twig representing a new variation of the same species which either is lost or spread amongst the population. An example of such a tree is here:

http://en.wikipedia.org/wiki/File:Age-of-Man-wiki.jpg
This is the easy to visualize version.

http://en.wikipedia.org/wiki/File:ITOL_Tree_of_life.jpg
This one is the more current version.

Our own history has had many stages each providing small new variations to our now current versions. Some examples are Australopithecus afarensis, homo habilis, homo erectus, homo antecessor, homo neanderthalensis, homo sapiens and homo sapiens sapiens. What happens is you have a characteristic such as being tall, and if that benefits you enough to gather more food for your group, you are able to have more children, giving that same gene of height to your kids, they too provide more food, giving them more kids and so on, the shorter members of the group have a harder time providing food giving them less chances to have kids so eventually the shorter gene gets wiped out by disadvantage, this process is the natural selection process. It’s not an overnight thing, it takes hundreds or thousands of generations for these steps to happen, which is why many people just do not comprehend the process. Humans have only really been observing animals closely for the last few hundred years, which in most species you will not see much adaptation especially if you aren’t looking for it.

Darwin’s discovery of the process in 1859 started that very search to provide clues which could be searched for, and have in fact been proven, verified, and even tested in some cases. Though testing may be hard for many species life spans to provide enough generations to see results, it can be observed in much shorter living species such as bacteria which can go through a hundred generations in an afternoon. A newly evolved bacteria for example was found in Asia that eats nylon. Nylon being a man made material and has only been invented in the last 100 years, so a species that survives solely from it is the perfect example of evolution creating new species and not just small adaptation. On a side note, the discovery of DNA was something that could have completely thrown Darwin’s claim out the window, but everything they found through studying DNA and genetics has verified Darwinian evolution even further.

So after our split, the chimps went their way and evolved in different ways eventually arriving at the current 2 species, the human route was a route that allowed for further and further modification to the genes we passed on through spreading to new areas, new animals to hunt, new climates to survive, new ways had to be found to survive and this is what drives natural selection. If you look at birds for example the finch, there are many types of finch ranging quite a bit in size, shape color, beak shape etc. All driven by the area of the world they live in. In one area the larger beaks provide an advantage and so they reproduced at a higher rate passing along the large beak gene, and in other areas where there were more predatory animals, the color of their feathers may deter them and so that gene is passed along at a higher rate.

So current apes are still apes because they are on a different branch, even though we are part of the great ape family or larger branch Hominidae, our particular branch is the road filled with lots of extinct species (such as neanderthals) and gene variations that either didn’t work causing extinction or did work and were advantageous to them at the time allowing them to survive until the next variation arrived. As I mentioned there were times where more than 1 species of “early humans” were both existing and living. Neanderthals as an example were alive at the same time as some homo sapiens and some interbreeding took place between the two, but neanderthals themselves have since gone extinct and only a small percent of the population having an ancestry relating to them.

In closing, evolution is not done, it doesn’t end, and it is always able to continue. It just needs a new genetic variation or mutation that is advantageous and then just has to spread among the population, such as being able to ingest milk as an adult, blond hair, and immunity to certain virus or disease.

Hopefully this answers the question, if not I can explain any piece of detail that might have been overlooked or not explained well. I tried to keep myself focused, but ended up jumping around and repeating things, sorry for that, but the message should still get across somewhat clearly.

Update: I recently came across this video from the Richard Dawkin’s foundation for Reason and Science. It is a brief answer to this very question. Video is only about 2 minutes long. Take a peek. Enjoy.

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