At the Zoo

The Lincoln Park Zoo in Chicago has two large primate facilities. One is the Regenstein Center for African Apes, a formidable facility which houses, at a guess, 20 some gorillas and chimpanzi. (I find it an ironic connection that the ape habitat bears the same name as the giant concrete block facility on the University of Chicago campus which houses a lot of books and nearly as many miserable undergraduates similarly ‘trapped’ by their studies. Despite their very bookish and antisocial complaints to the contrary, the undergrads would actually have an easier time leaving their Regenstein, should they ever choose to. Most don’t. They truly are very miserable people, and make me appreciate having gone to a state school.)

The Center provides some of our closest relatives very ample room to live and interact, both indoors and out. Also, they used to have a really young gorilla- not dead, just older now- who at the time did many cute and interesting things, like ‘fishing for ants with a stick’ or ‘messing with his dad.’ They’re just like us!! There are always massive groups of people watching the apes through the glass, even though they don’t put on much of a show. Sometimes they eat lettuce though. Also, sometimes there are rabbits in their habitats, which is sometimes the most exciting thing going on.

The ugly stepsister of the ape habitat is the Helen V. Brach Primate House, which is in itself actually quite nice. However, it has the unfortunate luck to be positioned right next to the very, very cool ape habitat. It’s kind of the Ashlee Simpson Primate House to the Jessica Simpson Center for Apes, if Jessica wasn’t completely vapid and Ashlee was, well, at least attractive. Is that too much to ask?

(The Primate House was funded with generous support from the Helen V. Brach foundation. Yes, Brach as in the candy. Pretty interesting story about what happened to her…)

The primate house holds probably 30 or so primates of various species- probably these could be called ‘monkeys’ but I’m not sure about the technical ramifications of that term. Seems that it may not be p.c. any more. One monkey of note in this facility is a young male with only one arm. He wasn’t born that way. Rather, no one told this poor monkey that the guy in Arrested Development who George used to teach the kids a lesson never ACTUALLY lost his arm. As a result, to teach the lessons “That’s why you reuse reduce recycle,” “That’s why you clean up after yourself you filthy brat,” and “That’s why you don’t leave food wrappers around or you’ll get ants,” he actually went off and lost it. Sounds like something Jessica might do to me.

Anyhow, one warm summer day some time ago the beautiful Brigitte and I were at the zoo in the Primate House. Whilst we were partaking of a baby monkey-of-some-sort romping about on a branch, an uneducated but otherwise perfectly pleasant couple also partook nearby. Now, why in the world would I jump to the conclusion that these pleasant people were uneducated? Well, usually when dealing with masses of humanity that’s my underlying assumption. However, I like being at the zoo, and the little orange monkey was pretty entertaining, so, in conceptual hindsight I’ll give myself the benefit of the doubt and say that I wasn’t being a complete highbrow/arrogant jerkface. What substantiates the assessment then?

They stood beside us for a moment, entertained. Then the fellow said “Just think Dolly, but for one chromosome, that would be you.” Brigitte and I locked eyes and just about split apart laughing. We are scientists. We enjoy the biological-knowledge-based shortcomings of others. However, we contained ourselves because we’re not the “Oh hey everyone did you hear what this idiot just said, what an idiot!” know-it-all jerkfaces. We’re more the reserved, listen to this schmuck who thinks he knows something but he doesn’t jerkfaces.

So why, you ask, is this so preposterous? After all everyone knows humans and chimps are at least 98% the same genetically, but look how different we are, it must come from somewhere, and so why not from an extra chromosome? Well, for one, humans have 23 chromosomes- the molecularly massive frameworks that contain all of our DNA- so if we had a whole SPARE chromosome that right there would be about 4.5% difference. Additionally, chromosome number turns out not to mean much. Humans have 23 and chimps 22, the difference being that the human chromosome 2 exists as two smaller chromosomes in chimps (they’re numbered by size). To illustrate the point better, however, rhesus macaques, a species of monkey, have 21 chromosomes, mice 20, dogs 38, cows 30, chickens 33, fruit flies 6, and yeast 16. Given that this list is in approximate ascending order of divergence time from humans (that is, the last common ancestor that gave rise to humans and mice lived more recently than the last common ancestor of humans and chickens) (well, unless you’re Sarah Palin), you can see that there is no trend over time such as “gain skeleton, add one chromosome, collect $200.” That would clearly be meaningless because jawed fishes clearly wouldn’t have much to do with $200. So, I enter this as my depiction of why a solitary, discrete chromosome is not the reason I did not have orange hair and crawl a branch within 6 months out of the womb. Neither is the reason for me not doing that that I’m not Irish nor was I ever very good at climbing trees. It has to do a bit more with real genetics.

And so, this would allow Mr. Geneball an opportunity to expound on how exactly it is that humans and monkeys come to look and behave considerably differently. There are two factors at play here. One is the aforementioned 98% coding sequence identity. By the mathematical property of subtraction this then means we’re about 2% different. Not much. But when you consider that this is over the span of millions and millions of pieces of information stored in our DNA, this becomes a considerable difference- on the order of tens to hundreds of millions of differences in the code that biology uses to shape its cells, and that cells use to shape tissues, and tissues to organs, and organs to peoples, monkeys, or flies. So, this 2% difference can have a big effect much like a giant retailer like Wal-Mart can make a fat profit while selling things for just over their production value. (At least that’s what I get the impression they do- I read Nature not Fortune)

The second factor is a bit of a trick that lies in the details used above. I referred to our differences specifically as ‘coding sequence identity,’ because that number was determined comparing just the sections of DNA that we know code for a particular something- that is, comparing the genes. Turns out, only a fraction of the 3 billion DNA base genome we tote about in every cell are genes, that is, are used to make a protein, which will do most of the work of the cell. Some of the rest regulate the genes- they interact with various proteins to allow or prevent nearby genes to be made into proteins. Some help regulate getting the giant pieces of DNA into separate cells when a cell divides in two. And some, we don’t really have a damn clue what they do. And all of these sections of DNA vary as well, including not only single-bit changes but also larger scale rearrangements, duplications, and deletions. The net effect of this non-gene, or ‘non-coding,’ material is that the genome becomes a monstrously complicated network of switches and interactions, and alterations in these regions allow very specific differentiation into humans, monkeys, or flies. For instance, splitting human chromosome 2 in two parts, as happens in chimpanzee, likely puts these genes in entirely new non-coding contexts. This change, along with a multitude of others, ultimately adds up to enough subtle developmental differences to keep me on the outside of a thick glass wall, at least as long as I keep the thoughts in my head inside.

The details are as a whole a bit fuzzy still, but those are the concepts by which these things work. It’s a combination of a massive information source which makes a few slight changes cumulatively significant and a synergistic effect where not only gene products but also how they are regulated and what they regulate can produce quite different results with similar starting materials.

But for millions of changes and rearrangements, boy, things would be a lot different.