Peter Watts was (is?) a researcher, a frighteningly-erudite marine biologist, so these are not your stereotypical vampires of teen-fiction:
"Homo sapiens vampiris was a short-lived human subspecies which diverged from the ancestral line between 800,000 and 500,000 year BP. More gracile than either neandertal or sapiens, gross physical divergence from sapiens included slight elongation of canines, mandibles, and long bones in service of an increasingly predatory lifestyle. Due to the relatively brief lifespan of this lineage, these changes were not extensive and overlapped considerably with conspecific allometries; differences become diagnostically significant only at large sample sizes (N>130).Why does Watts need a highly-intelligent, empathy-free sociopath as a central character? Because his book is an extended examination of consciousness: what is it, what is it good for (or not) and how sure are we that it even widely exists? His alien protagonists are also not overly-burdened with consciousness but it doesn't seem to slow them down any. And bringing back your species' top predator - even on a leash - might not be the smartest option.
However, while virtually identical to modern humans in terms of gross physical morphology, vampiris was radically divergent from sapiens on the biochemical, neurological, and soft-tissue levels. The GI tract was foreshortened and secreted a distinct range of enzymes more suited to a carnivorous diet. Since cannibalism carries with it a high risk of prionic infection, the vampire immune system displayed great resistance to prion diseases, as well as to a variety of helminth and anasakid parasites.
Vampiris hearing and vision were superior to that of sapiens; vampire retinas were quadro-chromatic (containing four types of cones, compared to only three among baseline humans); the fourth cone type, common to nocturnal predators ranging from cats to snakes, was tuned to near-infrared. Vampire grey matter was "under-connected" compared to human norms due to a relative lack of interstitial white matter; this forced isolated cortical modules to become self-contained and hypereffective, leading to omni-savantic pattern-matching and analytical skills.
Virtually all of these adaptations are cascade effects that— while resulting from a variety of proximate causes— can ultimately be traced back to a paracentric inversion mutation on the Xq21.3 block of the X-chromosome. This resulted in functional changes to genes coding for protocadherins (proteins that play a critical role in brain and central nervous system development). While this provoked radical neurological and behavioral changes, significant physical changes were limited to soft tissue and microstructures that do not fossilise. This, coupled with extremely low numbers of vampire even at peak population levels (existing as they did at the tip of the trophic pyramid) explains their virtual absence from the fossil record.
Significant deleterious effects also resulted from this cascade. For example, vampires lost the ability to code for -Protocadherin Y, whose genes are found exclusively on the hominid Y chromosome. Unable to synthesise this vital protein themselves, vampires had to obtain it from their food. Human prey thus comprised an essential component of their diet, but a relatively slow-breeding one (a unique situation, since prey usually outproduce their predators by at least an order of magnitude). Normally this dynamic would be utterly unsustainable: vampires would predate humans to extinction, and then die off themselves for lack of essential nutrients.
Extended periods of lungfish-like dormancy (the so-called "undead" state)—and the consequent drastic reduction in vampire energetic needs— developed as a means of redressing this imbalance. To this end vampires produced elevated levels of endogenous Ala-(D) Leuenkephalin (a mammalian hibernation-inducing peptide) and dobutamine, which strengthens the heart muscle during periods on inactivity.
Another deleterious cascade effect was the so-called "Crucifix Glitch"— a cross-wiring of normally-distinct receptor arrays in the visual cortex, resulting in grand mal-like feedback seizures whenever the arrays processing vertical and horizontal stimuli fired simultaneously across a sufficiently large arc of the visual field. Since intersecting right angles are virtually nonexistent in nature, natural selection did not weed out the Glitch until H. sapiens sapiens developed Euclidean architecture; by then, the trait had become fixed across H. sapiens vampiris via genetic drift, and—suddenly denied access to its prey—the entire subspecies went extinct shortly after the dawn of recorded history."
Watts' authorial persona is super-smart aggressive: he writes like Richard Morgan (Takeshi Kovacs) or Greg Cochran (the non-fictional West Hunter). The aggression seems to reflect the real-life person - a criminal record locks him out of the USA.
The case for the prosecution in "Blindsight" doesn't really work, as I think the author concedes. But what a case! You will understand the sheer depth and ingenuity of his thinking when you truly understand this passage.
"Now you get it," Sascha said."Blindsight" is available for free on the author's website but as he has to eat, it might be better to buy it and the popular sequel Echopraxia on Amazon. Or both together, bound for Kindle as Firefall.
I shook my head, trying to wrap it around that insane, impossible conclusion. "They're not even hostile." Not even capable of hostility. Just so profoundly alien that they couldn't help but treat human language itself as a form of combat.
How do you say We come in peace when the very words are an act of war?
"That's why they won't talk to us," I realized.