Devil Bones by Kathy Reichs Read Free Book Online

known males and known females of specific racial or ethnic backgrounds. Since tight-fitting cheekbones and a relatively long skul ruled out Asian and Native American ancestry in this case, I ran comparisons using Caucasoids and Negroids.
    No surprise. No matter black or white, the Greenleaf skul classified with the girls.
    Evaluation of race is a bit more complicated. Just as they are for sex determination, the potential reference groups are composed of both sexes of known blacks, whites, American Indians, and Japanese, as wel as Guatemalan, Hispanic, Chinese, and Vietnamese males. That’s what the Fordisc database holds.
    I ran a two-way comparison between black and white females.
    My unknown classified with the former. Barely.
    I checked the interpretive stats.
    A posterior probability, or PP, gives the probability of group membership for an unknown based on its relative proximity to al groups. Major assumptions are that variation is roughly the same within groups; that means and values differ between groups; and that the unknown actualy belongs to one of the reference groups you’re using. That last isn’t necessarily true. A DFA wil classify any set of measurements, even if your unknown is a chimp or hyena.
    A typicality probability, or TP, is a better indicator of actual group membership. TP’s suggest the likelihood of an unknown belonging to a particular group based on the average variability of al the groups in the analysis. TP’s evaluate absolute distances, not relative distances, as with PP’s.
    Think of it this way. If you have to fit your unknown into one of the program’s reference groups, a PP tels you which is the best choice. A TP tels you if that choice is realistic.
    The PP on my screen said that for my unknown, black ancestry was a greater likelihood than white. The TP suggested her head wasn’t put together like those of the black ladies in the data bank.
    I remeasured and recalculated.
    Same result.
    Numbers go one way, overal deductive judgment goes another? Not uncommon. I stick with experience. And, since genes pay no heed to stats, I knew there was the possibility of mixed ancestry.
    Flipping to the cover sheet, I filed in boxes on my case form.
    Sex: Female.
    Ancestry: Negroid. (Possible Caucasoid admixture.)
    Age: Fourteen to seventeen years.
    Sweet Jesus. Just a kid.
    Staring into the empty orbits, I tried to visualize who this young woman had been. Felt sad at the loss. My mind could conjure up rough images of her appearance based on the black girls I saw around me. Katy’s friends. My students. The kids who hung out in the park across Colege Street. I could envision dark hair and eyes, chocolate skin. But what had she felt? Thought? What expression had molded her features as she fel asleep each night, woke each morning?
    Fourteen to seventeen. Half woman, half child. Had she liked to read? Ride a bike? A Harley? Hang out at the mal? Did she have a steady boyfriend? Who was missing her?
    Had mals existed in her world? When did she die? Where?
    Do what you do, Brennan. Learn who she was. What happened to her.
    Setting sentimental musing aside, I refocused on the science.
    The next boxes on the form asked for PMI and MOD. Postmortem interval. Manner of death.
    With dry bone, leached of flesh and organic components, time since death can be even tougher to nail than race.
    Gently, I hefted the skul in one palm, testing its weight. The bone looked and felt solid, not porous or degraded like old cemetery remains or archaeological materials. Al visible surfaces were stained a uniform tea brown.
    I looked for cultural alterations, such as tooth filing, cranial binding, occipital flattening, or surgical boring. Zip.
    I checked for indications of coffin burial. The skul retained no funerary artifacts such as morticians’ molding wax, trocars, or eye caps. No threads or fabric shreds. There was no embalmed tissue. No flaking of the cortical bone. No head or facial hair.
    I shined a smal flashlight