Gorilla Feet

I promise every post in Chicago won't be about the apes at the zoo, but there will probably be a few more after this one too!

This is a gorilla foot:

Gorilla Foot

I was able to get such a great picture because the gorilla was sleeping with his foot up on the glass.  I touched the glass after I took this pictures, and it appeared to be about 1.5 inches thick.  After seeing the adult male gorilla kick the door in his enclosure a few days ago, I'm hoping that glass is thick enough!  That gorilla is massive and extremely strong. 

Gorillas are usually fairly mellow, and they seem to have less intense social interactions than chimpanzees do.  They do engage in grooming behavior, aggression and play, but their interactions are much less constant than the chimpanzees'.  They are vegetarian, mostly forest floor dwelling and less active in general than chimps.

Gorilla's forelimbs are massive and long.  Their arms are about six times stronger than ours.  Their legs are much smaller, though still strong.  Even though they spend lots of time on the forest floor, they are still very good climbers, and they use their arms to amble around the branches and vines with ease. 

Gorilla's feet have opposable thumbs.  They are good at grasping things - branches or food, but they are not good at walking upright.  Our feet have all toes pointing forward, which is great for bipedal locomotion, but have you ever tried to pick up anything with your toes?  Not easy.

Beyond shape, there are many similarities in our feet and gorillas'.  First, scroll back up to the picture and notice the prints.  I can't call them fingerprints, because they are on the sole of the foot, but we have these too.  We have prints all over the bottom sides of our fingers, palms, toes and soles, and so do gorillas.  These prints are due to ridges in the subskin (dermis) where it attaches to the upper skin (epidermis).  The ridges and valleys allow for more contact between the two layers, which reduces separation of the layers from friction.  What that means in everyday English is that it reduces the incidence of blisters.   

Next, notice the nails.  These guys have fingernails and toenails, not claws.  Nails are good for manipulation of plants and small structures, and they protect the fingers from stomping or insect bites, but they're not good for ripping flesh.  Since gorillas are herbivores and big and strong, they don't need claws for food or defense, so they have nails.  We are not entirely herbivores, but we use tools to catch our animal prey, so we don't really need claws either.  We do, however, need to manipulate small items, and nails are useful for that.

Gorilla and human feet are homologous structures, meaning they have the same evolutionary origin, and have developed from the same bone and muscle pattern.  Since gorillas and humans separated on the evolutionary tree a long time ago (well, in evolutionary time, not so long ago) and have adapted to different environments, our feet have evolved in slightly different directions too.  Scientists think the evolutionary ancestral foot to humans and gorillas was more like the gorilla one, though probably smaller and more hand-like.  Primate ancestors were even less bipedal and more tree-dwelling. 

Zoos and Conservation

The Lincoln Park Zoo is on my daily walking route now.  It's free and open to the public, and I can power walk right through or linger and marvel, depending on how I'm feeling and what the animals are up to.  It's a small zoo, but the construction of several of the animals' enclosures allow for jarringly intimate observations of the animals.

The gorillas and chimpanzees, in particular, are housed in such well-designed pens that I find myself moved and astonished by them as has not occurred in other zoo experiences.  The floors are elevated so the monkeys eyes are level with mine and the high-quality non-distorting glass allows a 1" distance between my skin and theirs.  I can see subtle changes in facial expression, lines in the soles of their feet, and individual hairs between the fingers of grooming chimps. 

A chimp comforting another after she was refused food by a male.

The resemblance in anatomy, emotion and behavior to humans makes these animals more interesting to watch than any other in the zoo.  Their enclosure is interesting enough that they seem to feel comfortable exhibiting a variety of the complex behaviors I have read about in Jane Goodall's accounts.  They groom each other, ask for food, diffuse conflicts, climb, play and interact with their surroundings.  It is difficult not to assume one understands their motivations and behaviors, since they look so much like us.

I watched this chimp make a nest of burlap sacks, try it out several times, readjust the burlap then roll over and suck her toes.

After awe and utter fascination, the strongest sentiment I have when watching these creatures is how unfair it is that they are put on display in fancy prison cells.  They clearly have lesser environments than they would in the wild.  Their behaviors and free expression are constricted.  They are aware of the constant stream of eyes looking at them.  The big silverback gorillas protest their enclosure by sitting with their backs always to the glass.  The animals are not happy about being enclosed.  I always imagine some more powerful aliens coming to earth and capturing a few of us for their zoos at home.  We would be outraged.

And yet, there is some considerable benefit to animals in zoos from a conservation perspective.  Zoos create opportunities for the development of strong affection of humans for animals, making us care about their continued presence on earth.  We are more likely to push for the conservation of chimpanzee habitat after experiencing reverence for them in a zoo.  In the worst case scenario, zoos have been the last refuge for species that are almost extinct.  The black-footed ferret once existed solely in zoos and has been reintroduced into wild land.  Zoos also provide the means for maintenance of genetic biodiversity, by shipping sperm or arranging for matings, so that a species has a wider variety of genetic combinations, reducing the likelihood of extinction.

If it were up to me to decide to free all the animals in zoos or keep them, I would be strongly conflicted.  Clearly it unethical to keep socially complex animals in tiny, uninteresting enclosures.  As zoos expand and enrich their animals' habitats, the balance shifts more toward the value of zoos, especially since humans will apparently destroy all natural habitats without education and enforcement of the alternative.  Zoos are an imperfect solution, but it seems that at least some zoos are necessary in our current world.  I know I'm going to spend a lot of time in the ape house at our zoo while I'm in Chicago, but my amazement will always be tinged with pity.

A Love Letter to A. P. Environmental Science Students

It's getting close to Halloween, and the scariest thing for most APES students is the nitrogen cycle, so why don't we tackle that today.  The dreaded nitrogen cycle strikes fear into the hearts of Environmental Science students everywhere because it's so difficult and so necessary to know.  But just like vampires, mummies and werewolves, it gets more interesting the more you understand it (though it still might scare the you-know-what out of you!).  Don't fear - you can do this!

Do you know why I put a picture of this Chicago bean tree (actually a honey locust) here?

First of all: what is nitrogen and why do we care so much about it?  Living things on earth are mostly made of the atoms carbon, hydrogen and oxygen, but proteins need a little nitrogen.  No living thing can live without proteins, therefore nitrogen is necessary for life.  Nitrogen, however, is in short supply, at least in a usable form.  If you think of atoms like Legos, each atom would be a different type of Lego.  Atoms can bond together to make larger structures like proteins, carbohydrates, DNA and oils, which then add up to whole organisms, just like Legos can be put together to make bigger things.  Nitrogen atoms are the special Lego pieces that are rare but that you can't build anything without.  Animals get all their nitrogen from eating protein in food.  When you eat food, your body takes apart the food's Legos (atoms) so that it can put them back together again into the molecules you need (or your body burns the Legos for energy, but the analogy kind of breaks down there).

Usable form?  Take a big, deep breath - it will help calm you down, plus it demonstrates the next concept.  What you just inhaled (air, hopefully) is 78% nitrogen.  OK, exhale.  You just exhaled every bit of nitrogen that you had inhaled, absorbing none of it.  Nitrogen in the air is in the form of N2 (I don't have subscript), or two nitrogen atoms double-bonded to each other.  There is actually a triple covalent bond holding two nitrogen atoms together in N2, which makes them nearly impossible to get apart.  Think of identical Lego pieces so hopelessly stuck together that you have to go get a kitchen knife to separate them.  Your lungs don't have the biological equivalent kitchen knives, so they can't break apart the nitrogen atoms to use them, and all the nitrogen you inhale is useless to you (except that it makes our atmosphere very stable).

The Kitchen Knife Monopoly:  Nature runs a tight kitchen, and it won't let you play with knives.  Only specific soil bacteria are allowed to have knives.  By which I mean only bacteria can fix nitrogen from it's stuck form to separate, useful atoms.  The separate atoms are quickly bonded to hydrogens to make ammonia (NH3).  The name of this process is nitrogen fixation.  It is thought that the ability to fix nitrogen evolved once on this planet when bacteria were pretty much the only critters here.  Everyone else after that found that it was easier to trade with bacteria than to evolve their own way of fixing nitrogen.  It is extremely difficult to fix nitrogen because a lot of energy is required to break the triple bond between two nitrogen atoms.  Bacteria expend a lot of ATP to break the nitrogen, but no one else is going to do it for them, so they just get on with it.

Wheeling and Dealing:  Anyone else who wants fixed nitrogen has to get it from bacteria.  They can wait for the bacteria's waste and absorb that straight from the soil in the form of ammonia, but bacteria aren't very wasteful, and there isn't much nitrogen available this way.  Some organisms have found a better way to get nitrogen: they can strike a deal with the soil bacteria.  Many plants, especially legume-type plants, have a mutualistic symbiosis with the soil bacteria.  Plants provide the ATP and some oxygen in exchange for lots of ammonia.  Legumes even provide specialized little lumps (nodules) on their roots to house the bacteria. 

What About Us?  As I said earlier, we get all our nitrogen from food.  We need protein in our diet because of the nitrogen in protein.  Think of foods that are high in protein.  Did you say meat and eggs?  You're right, but think of vegetarian foods that are high in protein.  Hopefully you said beans, peanut butter and tofu.  When you think about it, you realize that all these foods are legume-type plants, which makes sense because legumes are able to get more nitrogen from housing nitrogen-fixing bacteria in their roots.

Random picture of black beans!

But that's not all is it?  Sorry, no.  When we learn about Environmental Science, we always learn about the full cycle of things - externalities, life-cycle costs, recycling, etc.  We have to finish the story.

Energy From Nitrogen?  Since it takes so much energy to break N2 apart (a reduction reaction for you chemistry folks), it would follow that energy can be had from getting those two nitrogens back together.  In fact, that's just what TNT and fertilizer bombs do is allow a large quantity of nitrogens to reunite - boom!  Bacteria in the soil can take advantage of single-nitrogen molecules and get some energy from oxidizing them in two different ways.  The first way is called nitrification, in which bacteria take ammonia molecules and make nitrite, then nitrate ions for energy.  Extra nitrate ions left in the soil from this process are very easy for plants to absorb and use.  You can think of this as half-oxidizing the nitrogens (sorry, chemistry teachers), and releasing some of the available energy.  Fully oxidizing two nitrogen compounds results in the production of N2, releasing more energy and returning the nitrogen to that useless gas molecule in the atmosphere.  (We just came full circle!)

Still Not Done:  It helps to know the following trivia about the nitrogen cycle too.  (1) Animal waste and dead organisms contain a lot of nitrogen.  Soil bacteria break down that waste and release the nitrogen into the soil as ammonia (in a process called ammonification), which is available for plants to use.  You may have noticed this if you have a dog that pees in spots around the yard that result in greener grass patches.  If your dog always pees in the same spot, you no doubt notice that too much ammonia is toxic.  (2) Agriculture results in nitrogen being absorbed from the soil into plants, then plants being carted away to markets, along with the soil nitrogen (where did all the good Legos go?).  Soil nitrogen must be replenished with chemical fertilizer, manure, growth of legumes or other fertilizer.  (3) Too much nitrogen in a body of water, say from fertilizer runoff or sewage overflows, can cause the plants to overgrow, choke out the sunlight and cause lower-down organisms to die, decompose and use up all the oxygen.  Then everything else in the water suffocates and dies.  This is called eutrophication and is worth understanding very solidly.  (4) Some single-nitrogen compounds can be made from the energy of lightning separating N2 molecules.  Also, humans use the Haber Process the break the N2 bonds to make ammonia for making bombs and fertilizer.  The Haber process uses lots of energy to split the N2.  It uses N2 from the air but gets hydrogens from natural gas (CH4), so making fertilizer is a very fossil-fuel-intensive process.

Decisions, Decisions

As I was walking on my new daily exercise route in Chicago (up Lake Michigan's shore and down through Lincoln Park and the zoo - tough, I know), I almost stepped on these two mating cicadas.  They made me ponder the behavioral decision-making processes in animals. 

Two-headed cicada!

I'll start with the assumption that behaviors exhibited by animals are generally the result of a long evolutionary history, with a little improvisation and chance thrown in here and there.  This means that behaviors exhibited by animals are ones that caused their ancestors to have more offspring and pass on the traits for exhibiting those behaviors to their offspring (thanks, Charles Darwin).

Clearly the mating behavior I observed in the cicadas is necessary for the production of offspring and passing on genes to the next generation.  However, the fact that the cicadas were mating in the middle of a well-traveled concrete pathway would seem to be counterproductive in the Darwinian struggle for progeny.  Cicadas as a species are probably in the middle of a subtle evolutionary shift wherein those cicadas that mate on tree branches and in grass survive more often than those that mate on concrete.  How genes could be involved in that particular behavior, I don't know.  But I do know that fairly complex behaviors have genetic components.  For example, type of tree branch used for nest site choice in birds can be genetic. 

Obviously the cicadas were incapable of the complex thought process needed to see that mating on a sidewalk would get them both squished and that they should just move 6 inches to the left into the grass.  Animals are not thought to behave rationally.  That means they don't weigh the pluses and minuses of behavioral choices - they just act.  This always brings me to the following questions:  If animals don't actually decide what they are going to do, why do they do anything at all?  And how do they know what they should be doing?

For behaviors to evolve, there has to be a way for animals to 'know' that they are choosing a good behavior versus a bad behavior.  There must be something similar to pleasure and pain to reinforce good and bad choices.  In fact, the hormone that causes pleasure and contentment in humans (oxytocin) has been found in animals.  Animals also have adrenaline rushes, which elicit fear, panic and aggression in humans. 

Unfortunately, there is no way to know what an animal actually feels, so we must come to conclusions by analogy.  If oxytocin is released, the animal must feel something positive - perhaps calming or pleasurable, because that's how it works in people; if adrenaline is released, it must be the equivalent of scared, etc.  An animal that feels pleasure when it swallows food, drinks water, mates and finds safe locations to rest will probably survive.  An animal that feels fear when a larger, unfamiliar animal is near will respond by running away or fighting, both of which can extend life span. 

My favorite example of how this might work involves a study of my least favorite organism: roaches.  In a study to mimic roach behavior, scientists programmed tiny, roach-shaped robots to be still when they are in dark places and near other roaches and to run fast when they were in the light.  With this simple behavioral program, the roaches ended up behaving almost identically to real roaches.  I imagine that in real roaches' ganglia (little clusters of nerves throughout their bodies that act like little brains), they feel roach-y contentment in dark, tight spaces with buddies around, and they feel panic when the lights come on.  Oddly enough, in a test to see if roaches have a stronger preference for darkness or being around their roach pals, they chose the social environment over the safe environment.  Who knew roaches were such followers? More. 

There must be at least a few cicadas out there with a mutation that makes them fear stepping on concrete and therefore move away quickly when they find themselves on it.  The concrete-fear gene should confer an advantage to those cicadas, as they would be less likely to be scraped out of the treads of a tennis shoe one day.  Assuming humans keep building and using concrete sidewalks, some day all the genes for sidewalk-mating will have been eliminated, and only the concrete-fearing cicadas will have survived.  Cicadas as a species will be smarter, all without a single cicada having to think an actual thought.

Of course, humans always make their decisions based on cold rationality, because we have the ability to think and separate our emotions from our thoughts.  We have evolved brains capable of weighing our options and choosing the best path, so we don't need instinctual behaviors.  ...Not so fast!  We have plenty of positively- and negatively- reinforced behaviors: pleasure for eating, playing, making a home and mating, and pain from loss, fighting and overwork.  Humans have repeatedly been shown to act irrationally in less obviously evolutionary ways too.  Some of us take unnecessary risks, get pregnant too young or fall in love with the wrong person.  We have even learned that the average of millions of human decisions is not based on rational principles, as it is impossible to explain or predict the stock markets. 

We must be careful not to fall into the trap of assuming humans are so different from other animals.  There are evolutionary payoffs to many irrational behaviors.  Risk-taking can result in big rewards in status and resources, and perhaps more mates to pass on risk-taking behaviors.  Teen pregnancies tend to pass on genes early and often (not that I'm advocating teen pregnancy).  Romantic decisions are made at least sometimes based on evolved chemical signals (pheromones and antibodies) that might signal compatibility and more healthy offspring.  Human social tendencies can lead to careless financial decisions just as roach social tendencies can draw roaches into unsafe locations. 

So how much of our behavior is instinct and how much is logic?