VIABLE (22 page)

Next she examined his hearing. That afternoon she had downloaded software to her laptop that produced a series of tones at specific frequencies and volumes that were relayed through a set of headphones to each ear independently. She asked him to click the mouse pad to indicate whether the various tones could be heard. The software then plotted a graph showing the frequency of audible sounds on one axis and their loudness on the other. Alison knew that in humans the audible range of frequencies was usually between 20Hz and 20,000Hz, although a gradual decline with age at higher frequencies was considered normal. Most people over the age of twenty-five struggled to hear sounds above 15,000Hz. Prolonged and repeated exposure to high sound levels, such as he would have experienced from years flying jets and helicopters, was also likely to have caused permanent damage to the nerve endings on the basilar membrane, which should have further compromised his hearing.

It had taken him fifteen minutes to complete the test, the results showing that his range of hearing was in the range 2Hz to almost 60,000Hz, his ability to hear higher frequency sounds well beyond that of an average human. The software was specifically designed to be hard to fool, reducing the level of the tone until the subject indicated it was inaudible and then lowering it further, then raising it until the tone could just be heard once again, the process repeated until a number of consistent levels had been indicated. Alison had tested it on herself while she had been waiting for him to arrive. He couldn’t have been faking it.

Finally she performed a simple memory test, showing him random pages from a medical textbook before taking the book away and asking him to read them back to her. He seemed to have no difficulty memorizing pages of information after being shown them for only a few seconds.

By the time she had finished her initial tests it had been getting late and he left her in the lab to write up her notes while he went in search of food. He returned half an hour later with half a dozen cartons of Chinese takeout and a cheap bottle of white wine. They ate sitting at one of the lab benches, Alison occasionally putting her food down to add to her notes as a new thought occurred to her. When they had finished eating he leaned forward to see what she had written.

‘So, what did you find?’

She suddenly realized that she hadn’t discussed the results of any of her tests with him. All evening he had patiently complied with each of her instructions and she hadn’t once thought to share what she had found. Embarrassed, she immediately started to explain the purpose of each of the tests, and his results, starting with the eye exam. He let her continue for a few minutes before gently interrupting.

‘Alison, I’m pretty used to eye tests. I’ve been getting them regularly, at least when I’ve been flying, since about 1950. I’ve been faking them for almost as long. Most times that just involved remembering not to read too far down the chart. The docs I’ve come across generally wouldn’t bother with an internal exam unless they thought something was wrong, and so as long as you could read from the chart they’d leave the scope’ - he nodded up at the ophthalmoscope she had left on one of the benches - ‘in the desk drawer. Every once in a while one would however, and then they’d be curious about those additional blood vessels, or that reflective tissue that seems to be embedded in my retina. So then I’d have to convince them that I could see just fine, and generally they’d forget all about it and just pass me to keep flying. Seems like the military’s always short of men to fly their planes, particularly in wartime, and no-one’s really interested in grounding an otherwise healthy pilot just because they’ve found something they don’t recognize.’

‘But even though I would play it down it bothered me. Especially the reflective thing. It makes me easier to spot at night, and that’s not always a good thing in my line of work. Besides it can freak people out a bit, like it did with you when we first met, and again last night in the car park. Anyway, I spent a lot of time trying to work out what it was, and where it came from. I haven’t always had it, I’m pretty sure of that. I first noticed it in ’65, a few months into my first tour in Vietnam. I was an 11B, a grunt, back then. I’d known for some time that I wasn’t ageing, and I was starting to notice a few other things as well. Like the fact that I could see much better at night than the other guys in the platoon. Now I think it was those first few months in the jungle, night after night spent peering into the darkness, straining to spot whatever might have been out there trying to kill me, that triggered the improvements in my night vision.’

‘But then that led me to think, well, if that was true and my body was capable of developing itself, why would it also decide to give me that reflective thing, something that might make it easier for me to get spotted, something that would increase the chance that I might get killed? That puzzled me for a long time. I didn’t make the connection until years later. I was in Somalia at the time with the Nightstalkers and the CSAR guys who were stationed with us were showing us how to deal with bullet wounds. They’d head out at night in one of the Humvees with a flashlight and round up stray animals, goats mostly, and bring them back to the base. Then they’d shoot them and get us to practice fixing them up. And that’s when it occurred to me - a lot of animals have exactly the same thing. So I did some reading, and the answer was right there. The eye shine is caused by something called the
tapetum lucidum
, a layer of tissue that lies immediately behind the retina and reflects light back into the eye, increasing the light available to the photoreceptors. You see it when you shine a torch at an animal at night, or when you take a picture of your cat or your dog with the flash on.’

‘So that got me to thinking that maybe I had been looking in the wrong place all along, that maybe looking at the capabilities certain animals had might provide a better explanation for some of the other things that seemed unusual about me. I did a lot of reading after that, particularly about how certain animals had developed characteristics that allowed them to perform better in their environment. That collection of blood vessels you found at the back of my eye, for instance. In humans and most other mammals the blood vessels in the eye lie in front of the retina, which partially obscures the image the brain is trying to interpret. But birds’ eyes often have a structure called a
pecten
that lifts the blood vessels away from the retina, which solves the problem. It’s part of what gives birds such as hawks their extremely sharp eyesight.’

Alison remained silent while he talked. She hadn’t thought to simply ask him for an explanation of the things she had found. He had been aware of his abilities for decades, had been trying to hide most of them for just as long. Of course he would have tried to understand them, would have theories on where they had come from.

‘I’m sorry, I’ve been stupid. It’s just that I’m used to solving problems by myself. Most of my research involves examining tissue, cells, things that don’t have well-formed opinions on why they’re behaving the way they do. So what else can you tell me?’

He smiled again.

‘Well I have never found a way to prove any of this but I suspect that a higher density of photoreceptors also contributes to my vision, maybe also a better ratio of nerve ganglia to receptors. Again, most species of bird have many times the number of rods and cones per square millimeter that humans have.’

She nodded. His assumption made sense, but she would need to devise a method to test his theory. She scribbled a note to remind herself.

‘Anything else?’

He paused, as if for a moment unsure whether he should continue.

‘Yes, although some of it may sound strange until you understand what is possible when you look outside human anatomy.’

‘For instance?’

‘Well, I don’t like fluorescent lights.’ He nodded at the rows of strip lighting on the ceiling of the lab. ‘Or computer monitors.’ She gave him a quizzical look.

‘I know. This one puzzled me for a long time as well. Then I read that humans can’t distinguish movement at a rate greater than 50 Hertz – 50 cycles a second. Anything faster than that appears as continuous movement, which means that you can’t tell that a fluorescent light bulb oscillating at 60Hz is actually continuously flashing. It’s the same with computer screens. Sometimes you can see the effect when you see a computer being filmed on TV. But birds have flicker thresholds that are much higher, almost twice as high as humans in many cases. It helps them to pursue small agile prey through difficult terrain, something that to most humans would simply appear as a blur.’

‘But not to you.’

He shook his head.

‘When did you first notice that?’

He paused again, considering for a moment. He remembered playing games as a child, and how he would see, perfectly clearly, the ball leaving a friend’s hand, for an instant seemingly suspended in the air as it travelled the short space between them. His reflexes had always been good, but he suspected that at least part of his ability to react so quickly was due to the fact that he had been able to see what was happening around him with much greater clarity.

‘I think that’s one I’ve always had.’

‘So what else?’

‘Look at this.’

He reached behind her to pick up the ultrasound transducer she had used to examine his kidney, pulling up his t-shirt and pressing it to his stomach. He moved it around, watching the screen until he found what he was looking for.

‘Humans have an adaptive immune system, allowing our bodies to deal with a continual stream of new threats.’

Alison nodded. He was now in her area.

‘Yes. Antibodies, T-cells, Major Histocompatability Complexes, RAGs. A complex system of proteins that recognizes and marks foreign bodies for destruction.’

‘Right; but this system isn’t unique to humans. In fact we don’t even have the best version of it. There.’

He pointed to the screen. Alison leaned closer, puzzled. The resolution from the ultrasound was poor but she could just make out a pair of elongated structures located beneath each kidney. She hadn’t noticed them when she had examined him earlier.

‘Sharks were the earliest creatures to develop a multi-stage immunological response. It’s remarkably similar to that found in humans, only much older. They have each of the features you mentioned, as well as a spleen and thymus glands. In humans and most other vertebrates it’s bone marrow that’s responsible for producing red blood cells. But in sharks the skeleton is made of cartilage, not bone, which means no marrow. Instead the job of manufacturing red blood cells is performed by the spleen and two organs called the epigonal organ and the Leydig’s organ. The Leydig’s organ is found near the esophagus. I don’t think I have one. But the epigonal…’

‘…is found underneath each kidney.’

Alison had read about this. The two organs he had mentioned were entirely unique to sharks. No one was sure what, exactly, the Leydig’s organ did. But recent studies indicated that the epigonal organ was the site of T-cell differentiation, which meant that it played an important role in the animal’s immune system. As sharks were known to be remarkably resistant to cancers as well as a wide variety of other diseases, researchers had for some time been optimistic about the possibilities for applying what could be learned from studying their immune system to human medicine.

Alison also knew that the way their antibodies functioned was very different. In humans, the genes coding for various structural regions on a given antibody were separated by relatively large gaps of non-coding genes. Making a human antibody required that RAG proteins ‘cut and paste’ together antibody-coding genes, eliminating the intervening DNA. This process was responsible for the tremendous diversity of antibodies capable of being produced by the human immune system. But in sharks, the genes coding for the various functional regions of a given antibody were clustered, lying much closer together than in humans. As a result, some of these genes were fused to begin with, not requiring any cutting or pasting. The end result of all this genetic shuffling and non-shuffling was that sharks enjoyed the best of both immunologic worlds: they could cut and paste genes to enhance antibody diversity, but they also had ‘ready to wear’ antibody genes, allowing a much faster response to certain pathogens.

He pulled his t-shirt down, replacing the transducer.

‘For a while I even considered getting a vet to examine me. But then there was always the danger that I wouldn’t be able to keep a lid on whatever they might find. Besides, who wants to admit, even to themselves, that their physiology might be more suited to veterinary care?’

He smiled again, but this time the smile didn’t reach his eyes and Alison could tell the humor masked an issue about which he was sensitive. What must it be like to be so different and yet not understand why you were that way, or how you had come to be? He had clearly tried to study his genetic make-up, had tried to understand what mixture of genes might have made him possible. And in the process he would no doubt have come across each of the arguments why someone like him shouldn’t even have been allowed to come into existence. The erosion of the moral boundary between human and animal. The violation of some unspecified human right. There were plenty of good reasons why research in this area needed to be controlled, but she had always regarded arguments based on morality or some inherent, undefined quality of humanity as weak. The mixing of animal and human genetic material did not redefine the notion of human dignity. If the concept had meaning, it was only because humans might occasionally behave in a way that conferred that dignity, that their actions might from time to time command that respect. From what little she knew of the life he had led, from what her mother had told her about what her father had thought of him, it seemed that if there was a standard he had probably met it.

While she scribbled notes he talked about other abilities. Some he had always possessed, almost taken for granted, assuming that they were shared by others. And then a chance remark would make him realize that not everyone experienced the world as he did. Others he knew he had developed only later in his life, a response to a need his body must have recognized, although he admitted he was no closer to understanding the process by which this occurred than he ever had been. He told her things he had never considered sharing with another person, of abilities he himself was unsure he possessed, let alone understood. How he thought he could detect the slow orbit of the sun, the almost imperceptible movement of the constellations through the night sky. He explained how sometimes he thought he could see colors outside the spectrum of light normally visible to humans, and how at times when flying he thought he had even been able to detect the earth’s magnetic field.