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.