ends make their appearance early in our intrauterine development and then disappear – fortunately. How would you like it if you still had, pulsing at the sides of your throat, the gill slits that are found in the human embryonic pharynx? ”
Gideon took advantage of Adrian’s predictable pause for astonishment and appreciative laughter to barge in. “Uh, actually, Adrian, the subject isn’t going to be vestigial structures. Interesting as they are,” he added as Adrian’s face clouded. The great man very much disliked being told he didn’t know what he was talking about, however gently.
“No? What then?” he asked coldly.
“Mostly, the problems that resulted when we evolved from quadrupeds to bipeds,” Gideon said, and then, at Buck’s puzzled frown, added, “from four-legged animals to two-legged. You see, the difficulty is that we didn’t get totally redesigned. Nature – evolution – doesn’t go in for total redesign. Generally, it acts in a kind of piecemeal manner, fixing this or that up, but not taking into consideration how it affects other things. And getting up on our hind legs has affected a lot of other things, which is why we wind up with problems.”
“I don’t get it,” Buck said. “What problems?”
“Do you mean like fallen arches?” Henrietta asked. “Varicose veins in the legs? Oh, Lord, I can tell you all about those.”
“Yes, exactly. When we were on four legs, the blood from the leg veins had to overcome about two feet of gravity to get back to the heart. Now that we’re standing erect, your heart is a good four feet above the ground. Sometimes it’s too much for the venous pumping system. The blood can’t make it back up, it collects in the leg, and the veins bulge – varicose veins.”
“Oh, I get it. That’s pretty cool,” Buck said. “And fallen arches, what about them?”
“Ah, you see, our feet are unique in the animal world. In most four-legged animals, what they have are paws or hooves – nice, compact, simple structures wonderfully suited to running or walking. But primates were tree- dwellers to start, and almost all of them still are. So instead of four feet, they have what you might call four hands – a lot more useful for getting around up there. But ever since we humans started walking upright, our rear hands, so to speak, have been turning into paws to make walking more efficient. The problem is, they’re not really either; useless for holding things, but not built too well, not compact enough, for efficient walking. Not yet, anyway. The result is fallen arches. And bunions. And most of the rest of our foot miseries. ”
“So you mean I got flat feet because I used to be a monkey?” Buck exclaimed with his deep, pleasant laugh.
“Closer to an ape, actually,” Gideon corrected, unable to help himself.
“Ape, monkey, whatever,” Buck said happily.
Adrian seemed on the brink of putting in his own explanatory two cents’ worth, but then remembered he was still miffed and sat silently back without saying anything, pretending to be engrossed by the passing scenery. And looking more like a big, sulky baby than ever.
“But what may be the biggest problem,” Gideon went on, warming to his subject (once he’d gotten well launched, he was almost as hard to stop as Adrian), “is that the human pelvis has changed. See, when we walked on four legs the ribs were underneath our guts and took care of holding them in place, but once we stood up, that didn’t work anymore, and the pelvis constricted to meet the challenge. It went from being a pair of wide, flat, open blades to becoming a sort of bowl with only a tiny opening in the base, that could support the internal organs.”
“So why is that a problem?” Buck asked.
“Because while that’s been going on at the bottom of the spinal cord, the thing on top of it – the brain case – has been expanding. In other words, the birth canal has been getting smaller, while the biggest thing that has to go through it, the infant’s head, has been getting bigger. Giving birth hasn’t been getting any easier.”
“Tell me about it,” muttered Henrietta.
“And yet at the same time that the skull has been expanding,” Adrian said, finally unable to resist chipping in – he wasn’t one to stay irked very long – “the facial skeleton has diminished in size. We no longer have a snout, which means there is less room for our teeth. But our teeth have not gotten any smaller, and as you can surmise, that has meant trouble. The last teeth to come in, the third molars or wisdom teeth, often don’t have a decent space left, so they come in impacted, or crooked, or not at all. Good for the dentists, bad for the rest of us. I wouldn’t be surprised if, in another half-million years, we only have twenty-four teeth or so. Instead of thirty-two. Wouldn’t you agree, Gideon?”
With difficulty, Gideon restrained himself from pointing out that evolutionary change didn’t work that way. It didn’t work toward something. It worked from something, but even people like Adrian Vanderwater seemed to have a hard time getting that straight. It was the conditions of the moment that determined which genes would be favored and thus increase their proportion in the next generation. If the conditions changed, the “direction” of evolution would change. It had happened again and again, and was in fact the reason that most advanced life-forms were such seemingly patchwork products. It was a crucial understanding of the process that he freely badgered his introductory students into comprehending, but in this case he held his tongue. He was happy to have a cheerful, outgoing Adrian back with them and didn’t want to spoil things. He groped for a reply that was truthful and yet wouldn’t tick the archaeologist off again.
“I wouldn’t be surprised,” he said.
TEN
At the visitors’ entry to the cave, Henrietta’s presence once again got them waved through without need of fees or passes. Rowley, accompanied by Audrey and Corbin, was there to greet them in the entrance grotto. “You know, Gideon, you’re not on for half an hour,” he said around the bit of his unlit pipe. “There’s time for a look ’round if you’d like. I was about to give these two the tuppence tour. Can I interest you two in joining us? There’s a lot of history here.”
Only Buck took him up on it. Adrian rather frostily said he preferred to explore it on his own, inasmuch as he was already quite familiar with the history of St. Michael’s Cave, and Gideon said he wanted to have a look at Cathedral Cavern, the natural amphitheater in which he’d be speaking. He found it at the end of a narrow passageway, approaching it from the rear: a breathtaking, echoing, bowl-shaped hollow with a hundred-foot-high concave ceiling from which hung tremendous stalactites made all the more spectacular and mysterious by concealed amber, green, and orange lighting. Over the millennia, many of the stalactites had reached the bottom and congealed, making great, crenellated, floor-to-ceiling columns, also impressively lit.
The audience section consisted of twenty rising rows of red plastic chairs, each row sited on a white-painted concrete tier. Altogether, there was seating for a good four hundred people. The stage was simply a natural rock platform, slightly raised from the rest of the rock floor. The temperature was a comfortable seventy or so, but it smelled cold – cold, and flinty, and a little musty, but not unpleasant. About the way a great stone cavern ought to smell.
The walls, the floor, the stage – everything but the chairs – were slick with moisture, and shallow puddles had formed in the hollows in the stone floor. At either end of the stage was a huge speaker, and in the center a lectern had been set up with a rubber floor mat behind it. Gideon went down the tiers and up to the lectern to get a sense of the place from there, something he liked to do before he spoke. He placed his hands on either side of the lectern and looked out at the empty tiers. “Ladies and gentlemen-”
“Can I ’elp you, mate?” inquired a voice straight out of East London.
He turned to see a man in bib overalls, wearing a leather tool belt from the pockets of which protruded the multicolored, insulated handles of a dozen pliers, wire-strippers, and screwdrivers. Hanging on the outside were a couple of meters or testers of some kind. Even Gideon, whose knowledge of such things was laughable at best, recognized him as an electrician.
“No, just checking things out. I’m the speaker today.”
“Oh, glad to meetcher. M’name’s Derek. Going to be showing any slides, are we?”
“Nope.”
“PowerPoint?”
“Nope.”
