An Evolution Simulation

Originally posted at anthropologist.moonfruit.com

Someone I know directed me toward this nifty application you can download. Gene Pool (Swimbots) is an application where you are given a giant pool (see what they did there?) of these little creatures that have two goals in life:

1. Eat
2. Breed

You essentially get to “play God” and act as natural selection, choosing what type of Swimbots are most attractive to others, how fast the food population regenerates itself, etc. A dominant species becomes apparent pretty quickly. If it gets boring, switch up the factors acting against the Swimbots–make their food supply run low, change who they’re sexually attracted to, and how much food they need. I found this unbelievably entertaining and spent something like an hour playing around with them (yes, I am clearly a nerd). My population’s trends in dominance went something like this:

1. Lime green Swimbots become dominant quite quickly.
2. After about half an hour, red/pink become the dominant species.
3. Soon after, white and pale blue take over.
4. The pale blue begin to die and start mating with the lime green.
5. Lime green start to rise in number after two or three generations.
6. Red/pink take over again.

It’s a pale blue invasion!

You can also control what you’re watching, with filters such as “most prolific,” “mutual love,” and “oldest virgin.” Granted, watching the “mutual love” filter made me feel like I was watching some bizarre fetish porn, but nonetheless they are worth checking out. Some of the Swimbots are quite good at their life goals, and at one point I had a “most prolific” Swimbot who had produced 19 offspring.This is definitely worth a try, and it’s a fantastic time waster. To all of you putting off doing your work at the office (I’m looking at you, Dad), this simulation is for you.

Enjoy!

Evolution Simplified… Hopefully

Originally posted at anthropologist.moonfruit.com

Evolution is a really controversial topic, and a major reason it is so hotly debated is because it’s a very complicated process that people want simple answers to. Unfortunately, there really are no simple answers when it comes to evolution, and thinking about it requires one to open their mind and view the world over extremely vast periods of time. I feel like evolution is skipped over in high school biology classes, and it’s often not well explained. Personally, I didn’t begin to get a real grasp for evolution until I took a detailed physical anthropology course that involved a broad but thorough overview. So here is my gift to the internet: an attempt to explain evolution in a more simplified manner.

If one is to look at any given population, one will notice that there are differences between individuals. This could be a population of humans, or a population of pigeons. These differences are caused by genetic mutations that have occurred over time. The physical manifestation of these traits are phenotypic. Natural selection acts on physical attributes, and therefore works with phenotypic distinctions. (Click here to read about genotype-phenotype distinction)

There is genetic diversity in any given population. These differences between individuals can be beneficial in some circumstances, especially in certain biological niches. For example, say you have one large land area that has a wooded area and a lake, and one species of birds. Some of these birds inherited a mutation that gives them webbed feet. These birds are better equipped to live in the lake area, while the birds without webbed feet are better suited to the wooded area. These birds eventually split into two populations of birds, which each thrive best in the area they are physically adapted for. The birds who have webbed feet are more likely to be successful in the lake area than the birds without webbed feet, and therefore they are more likely to survive and produce offspring. This is more commonly referred to as natural selection–if an animal has qualities that will help it survive better in any given habitat, then nature is favoring it, while weeding out those who cannot survive. It is important to note that natural selection acts on the individual, while evolution acts on a population.

When I say “successful,” I’m referring to what some evolutionary biologists call “fitness,” which is essentially how well an organism reproduces. Those who leave the greatest number of offspring are considered more fit than those who leave behind few or no offspring. An individual is able to reproduce more and leave behind fit offspring if they are better adapted to survive in their environmental niche. An animal that is able to thrive in its environment is more likely to produce offspring.

Let’s go back to the two populations of birds now. These two populations are still technically the same species (a species is defined as a group of organisms who are capable of interbreeding in the wild and producing fertile offspring). However, if one were to wait hundreds of thousands of generations of these two populations of birds, they might eventually change enough as individual populations that they would no longer interbreed freely, or their genetic makeup would become different enough to become taxonomically defined as different species.

Evolution doesn’t happen suddenly, but instead takes millions of years. Because of this, we can’t see evolution happening (except in some microorganisms), but instead have to rely on the fossil record to tell us about our evolutionary past. The fossil record is patchy, however. Because of the vast amount of geological time that has passed, many skeletons and bodies of creatures that lived long ago were destroyed. To help illustrate this point, I’ve created some incredibly professional looking diagrams in Photoshop.

Let’s call this diagram “Figure A”
Figure A is of a phylogenetic tree of the evolutionary background of some creature. The purple rectangles are what the fossil record has uncovered. But that’s not what scientists have to work with.

Let’s call this diagram “Figure B”
Figure B is what happens when you erase the tree connecting all the creatures. Instead you’re left with some fossils, with no way of knowing what goes where, or how to connect certain species. That’s what paleoanthropologists (and anyone studying evolutionary history, really) have to work with. Because of this, there is a bit of guess work that needs to be done as to how to categorize our evolutionary pasts, which are somewhat helped by dating techniques.

Another point I’d like to bring up is the common misconception that humans evolved from chimpanzees. This isn’t the case. Let’s go back to our phylogenetic tree in Figure A. Humans and modern chimpanzees evolved within about 1 million years of each other. At one point in time, we shared a common ancestor (generally considered to be some time around 6 million years ago. Fun fact–background mutations occur at about a rate of 1% of a genome every 3 million years. Humans and chimps have roughly 98% identical DNA), so we were on the same branch. Now let’s refer back to the example of the species of bird that split into two distinct populations. Something somewhere changed along the line, the common ancestor (let’s call it Awesomus examplus for our purposes) split into two populations for whatever reason. Awesomus examplus is now two distinct populations that are adapting to their respective environments. Chimpanzees live in forests, while it is believed that our human ancestors evolved on the savanna. Because of tall grasses on the savanna, it was crucial for our ancestors to be able to stand up to look for predators. Because of this we developed bipedalism and somewhere in the process (unfortunately) lost our opposable big toes to accommodate standing up right. Our pelvises also changed into a more bowl like shape to accommodate the bone structure required for bipedalism. I could go on and on about the changes that happened over time, but the point should be clear–at some point, Awesomus examplus split into two populations who evolved into their current species of Homo sapiens and Pan troglodytes. When people say that our ancestors “branched out,” think of it in terms of a phylogenetic tree, and the literal meaning makes sense.

Hopefully this has helped to simplify evolution to some of you. The key is to think in huge chunks of time, not just our lifetimes.