Gorillas!

I suppose between the last two posts, first with a post with a comic about having sex with a partially shaved gorilla, and my last post involving bonobos, this was ultimately going to end up here.

Yes, it’s almost two years old, but still fascinating!

The first video was captured of two gorillas mating face to face. Yes, both gorillas AND bonobos are fond of the missionary position. Does this mean it’s considered less holy now?

By the way, speaking of partially shaved gorillas…

Bonobos!

One of the first things I learned in Anthropology is that there are five great apes:
-Orangutans (Pongo pygmaeus)
-Gorillas (Gorilla gorilla — original, I know)
-Humans (Homo sapiens
-Chimpanzees (Pan troglodytes)
-Bonobos (Pan paniscus)

When you tell most people this, they’re good up until the bonobo. “What the hell is a bonobo?!” they often ask. Bonobos are the only other extant members of the Pan genus. In lay terms: they’re closely related to chimpanzees. With chimpanzees, they’re the closest extant species to humans.

Originally called the pygmy chimp, the bonobo, like all other great apes, is endangered. Like all the great apes except the orangutan (who only live on the Indonesian islands of Borneo and Sumatra) come from Africa, and the bonobo’s home region is in the Democratic Republic of the Congo. Unlike the other great apes, however, bonobo society is run by females.

The one thing about bonobos that a lot of people seem to enjoy is the fact that they practice intercourse face to face. Yes, there are great apes who do it missionary style. Bonobos are very sexual creatures–they solve many problems by having sex and have no problem practicing frotteurism with members of the same sex. Strangely enough, this sex-driven, female run society is one of the most peaceful among the great apes.

Bonobos, like the other great apes, have considerable intelligence as well. They tend to be slightly less hyper and distraction prone than chimpanzees, which means working with them can often produce better results. Sue Savage Rumbaugh has spent many years researching intelligence in the great apes, and she’s a leading authority on bonobos.

One of my favorite online videos is about bonobos and their considerable mental capabilities. Because I am an insane nerd, I have watched this video at least five times and have shown it to many people I know. Now I am sharing it with you, internet! It’s a fifteen minute video, but when you have the time or are severely bored at work, sit down and check it out.

TED talk — Sue Savage Rumbaugh

A bonobo community peacefully existing together, possibly due to the fact that their leadership don’t feel it necessary to fight over who has the largest genitals.

Ardipithecus ramidus

Well, let me start this off by saying I haven’t done too much research on the recent Ardipithetcus ramidus announcement… I set the DVR to record the three hour Discovery Channel special and plan to sit down and watch it some time this week, at which point I’ll post about my thoughts. But my main reason for not going ape shit (excuse the pun) over Ardi is because it isn’t news to me.

My first thoughts upon hearing “Ardipithecus” were “Oh wow, they found another hominid in the genus to go along with Ardipithecus ramidus! COOL!”

… but then I looked and saw that the “new find” was Ardipithecus ramidus. This confused me, because I remember having to cram extinct hominid species for my Physical Anthropology final in May, and Ardipithecus ramidus was third on my chart of what species to remember (behind Sahelanthropus tchadensis and Orrorin tugenensis, respectively). I suppose this is one of those cases where the “big discovery” is of a species that the scientific community has generally considered a part of the hominid family tree for a while now.

So what I’ve gathered about our good friend “Ardi” from the New York Times article I linked above is this:
-The dental findings reveal her to have been more closely related to modern humans than the other species of modern apes. I’ll assume this also means she has the basic 2.1.2.3 dental formula of most hominids, but I’m not sure.

-She was a facultative biped, meaning she was capable of bipedalism but relied, for the most part, on a quadrupedal style of locomotion. The position of the foramen magnum seem to be similar to a modern human’s, so it is implied that perhaps bipedalism was possible but not the preferred style of locomotion. The pelvis is positioned so that bipedalism was possible, but she retained the opposable big toe, meaning she probably spent a fair amount of time in the trees. Lucy, who came roughly 1.1 million years later, was known to be a biped.

-She was probably not capable of brachiation, meaning she probably lacked the structure of the collar bone that modern brachiators and semi-brachiators have.

Overall, I’m excited to watch the special, even if I’ve read it tends to drag a bit. I’ll hopefully be able to report back positive reviews sometime later in the week.

Ardipithecus ramidus (“Ardi,” left), alongside Australopithecus afarensis (“Lucy”)

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.