Guest Posting by Kelly Kearse: Distinguishing human blood from that of other species

Distinguishing human blood from that of other species:

Too much monkey business?


The term “human blood” is consistently used in discussions of the bloodstains on the Shroud. Just how is human blood distinguished in the laboratory? And where exactly does the data on the Shroud stand? These questions are briefly discussed below.


Human blood versus animal blood

A scientist cannot just look at a bloodstain with the naked eye and tell that it’s human blood. For fresh blood, microscopic analyses may allow one to distinguish mammalian red blood cells from non-mammalian red blood cells due to the absence and presence of a nucleus, respectively. If sufficient numbers of (white) blood cells are present, chromosomal characterization (karyotyping) may be performed, at significantly higher magnification. Among primates, only humans contain 46 chromosomes; chimpanzees, gorillas, and orangutans contain 48. The chromosome number of other species is quite variable, for example pigs have 38, sheep have 54, dogs have 78, and cows have 60.

In aged bloodstains, such microscopic tests are not practical because blood cells become dehydrated and rupture within hours of drying. Species characterization of dried, aged bloodstains relies on serological (immunology) tests or molecular (DNA) analysis. Chemical tests cannot distinguish human from animal blood. For serological studies, human blood components (usually albumin or immunoglobulin proteins) are detected using antibodies that are generated in another species, for instance, rabbits. When utilized in the laboratory, such antibodies would not react with blood components from other animals, for example chickens or cows, because enough difference exists from their human counterpart proteins that the antibodies fail to recognize them.


A positive reaction in such tests usually results in the conclusion that human blood is present. However, this is where things get somewhat tricky. Even though such reagents are designated as “anti-human”, this only refers to the species in which they were generated. Cross-reactivity (or the lack thereof) must be independently verified. Species that are closely related to humans (i.e. non-human primates) express blood components (albumin and immunoglobulin) that are similar enough to those of humans to also react positively in such tests (see picture above). In forensic settings this is typically disregarded unless special circumstances warrant that such possibilities be considered (at a crime scene within a zoo, for example, or if someone were known to keep apes or monkeys as pets). In most situations, when it is stated that bloodstains tested positive for human blood, this underlying supposition exists. Strictly speaking, such serological tests do not distinguish human blood from the blood of other primates (monkeys or apes). If sufficient DNA is intact for molecular biology analysis, specific regions of certain genes may be targeted that have sequences unique to humans, which allow them to be effectively distinguished from those of closely related species.

Human origin of the blood on the Shroud

In the vast majority of discussions of the human nature of the bloodstains on the Shroud, the studies that are typically referenced are the experiments of Adler and colleagues and Baima Ballone and coworkers, utilizing serological tests for detection of common major blood components: albumin, immunoglobulin, ABO antigens. In fact, such studies do not distinguish human blood from the blood of other primates.

With the Shroud, primate may imply human but this is an extension beyond what the data actually show. Adler was appropriately cautious in concluding that the data only demonstrated that the blood was of primate origin, and even conducted experiments to evaluate the cross-reactivity of such “anti-human” reagents. Adler would also comment, “If you choose to think that the image you see is that of a chimp or an orangutan, you’re perfectly welcome to believe that…

To date, the only study that directly addresses the human nature of the Shroud bloodstains is an often overlooked report by Baima Ballone et al. that evaluated the expression of additional blood components found on red blood cells, specifically the M,N, and S antigens. (Such antigens have also been studied in the blood analysis of King Tut). The conclusion was that the bloodstains on the Shroud are characterized as MNS positive. What is most significant about these studies is that unlike M and N antigens, which are shared between certain primates and humans, the S antigen is exclusive to humans only. No S counterpart exists in other species, including apes or monkeys. This point was not emphasized (or mentioned) in the report, as the significance of this relationship among primates was not fully elucidated until several years later (in non-Shroud related studies). Of the six serological analyses of blood components on the Shroud, this brief study remains the single most definitive piece of serological evidence that directly addresses the human origin of the blood on the Shroud. For a more detailed discussion see: “Empirical evidence that the blood on the Shroud of Turin is of human origin: Is the current data sufficient?” recently published on The full-length manuscript is available at

Concluding Remarks

Taken together, the current serological data indicate the blood on the Shroud is of primate, i.e. human origin. Could more work be done in the laboratory to strengthen the conclusion that the blood is indisputably human? The answer is yes. Should there be sufficient doubt that the blood is in fact, human, and may represent the blood of a monkey or ape? The MNS studies say no. All other data are consistent with this finding. Moreover, Adler has effectively commented on the difficulties a forger would encounter in trying to apply clotting blood [of any species] to various regions on the Shroud. Since the original blood studies were performed some thirty years ago, significant advancements have been made in the development of serological and molecular tools that could prove useful in advancing previous information. For example, within the past few years, monoclonal antibodies have been generated that effectively distinguish human blood from that of closely related species. Similar to blood typing data, additional analyses would cross-check and verify previous findings on the bloodstains of the Shroud.

21 thoughts on “Guest Posting by Kelly Kearse: Distinguishing human blood from that of other species”

  1. A brief comment on this post: I realize that some may find the idea itself a little ludicrous, perhaps even insulting. I, myself, have never seriously thought it might be ape or monkey blood. Then, why go there? Because I think it’s important to critically analyze the data from as many different scientific disciplines as possible. This analysis is from the perspective of immunology, in which specificity is the cornerstone. The issue is isolated to examine “What does the data really tell us about the species origin of the blood?”

  2. What are we to think about the observation reported by Lucotte (“Vérités sur le Saint Suaire”, p.147 ff) on erythrocytes found on the Shroud (microscopic material collected by Giovanni Riggi di Numana) with diameters of 12.5-13 micrometer – much too large a value for human blood, according to this author.

  3. Some might argue that red blood cell membranes may reseal/fuse during the fixation procedure using for microscopic preparation; also, I believe the same author might have also reported that certain mineral particles may mimic the appearance of red blood cells. I think it would important to verify microscopic (visual) identification of red blood cells with some biochemical data, using microscopy together with (gold-conjugaed) antibodies directed against specific membrane markers, for example, to ensure that you are really looking at (reconstituted) red blood cells in the field. Baima Bollone has published a picture of what appear to be red blood cells on Shroud fibers in several of his books, but also includes a photograph of a silica particle in an adjacent panel to illustrate the similarities.

    1. Gérard Lucotte claims to have observed, in the micro debris aspired from the Shroud, 9 smaller erythrocytes that could be of primate/human origin (“Il s’agit sûrement d’hématies humaines” – p.150), and 55 larger ones that are not of primate origin (“elles proviennent probablement d’un grand mammifère domestique” p.179). His book also has some pictures of these red blood cells (p.273-276). Possibly this work is flawed but these claims should be addressed.

  4. Besides, one should be here reminded most if not all the archaeological bloodstains on the Turin Sindon have a colour between carmine brown and carmine red and look as if ‘fresh’. MOST LIKELY they are ‘fresh-looking’ re-dried aged re-moistened dried bloodstains strongly suggesting the burial sheet was first moistened or in-soaked with aqueous alkaline solution (e.g. ashes, Jerusalem limestone dust and/or urea residues mixed with pure living water/collected rainwater). Note: Jerusalem limestone dust mixed with water can gelatinized starch. Then the moistened/in-soaked burial cloth could have been subjected to a low temperature accidental/providential thermal imprinting process (e.g. ritual fumigation and/or corpse hyperthermia).

  5. Re “a silica particle”, reminder: adhesion of water insoluble (e.g. iron oxyde and/or other “opaques” present in the desert of Judea dust) onto the body skin and/or receiving flax surface could have resulted from the Sharaf (the biblical RuHa Qâdim or East Wind), an Israel wind more commonly known as Khamsin or the Dark Breath of the desert of Judea.

  6. Does anyone know of any old bloodstain, of any age, in any artifact, anywhere, that is coloured red, apart from those on the shroud? If so, has any microscopic investigation been done on it? If not, one cannot but wonder if the red colour, at least, is artificial.

  7. Reminder: human blood is red, ranging from bright red when oxygenated to dark red when not.

      1. Yes. See e.g. Brizzi V., Brizzi A., 2012: About Iceman’ Arrowhead: “Blood residue was visible in the area between the surface of the (arrow)point and the inner surface of the hafting wood. A single Hemastix test was made which returned a reaction of 1+. The surface was very hydrophobic and comparisons made before and after the test indicate that very likely residue was actually removed and tested. When removing residue from the basal thick deposits (Sample #24) more liquid was used and a longer soaking time was allowed. The subsequent liquid sample was viscous and reddish brown, consistent with experience removing thick blood residues from other archaeological tools (for example see Loy 1993)”.

  8. Hugh, why don’t you try just to mix fresh human oxygenated/non oxygenated blood with an aqueous alkaline solution, moisten or soak a piece of linen in it and have the moistened/soaked cloth dry out via low temperature fumigation and see what happens?

  9. I believe Ian Wilson mentioned in one of his books that Thomas Loy had told him he had seen a similarly colored blood on prehistoric artifacts-I believe that was in a conversation, don’t recall a specific reference for it. I looked for contact information for Dr. Loy last year on the internet and learned he was deceased.

    Perhaps someone else has run across other examples? Would be interesting to research into older artifacts and see if this ever comes up, and if so, under what conditions

  10. Re “a silica particle” (again), in his resume (Optical and chemical characteristics of the mineral particles found on the face of the Turin Shroud) Gérard Lucotte also wrote: “Some minerals, rounded in shape, can mimic – by aspect and color – true red blood cells (erythrocytes)”.

  11. Max Patrick Hamon :Hugh, why don’t you try just to mix fresh human oxygenated/non oxygenated blood with an aqueous alkaline solution, moisten or soak a piece of linen in it and have the moistened/soaked cloth dry out via low temperature fumigation and see what happens?

    Exactly. plus an addition of blood to other bodily fluid will stain and stay in a different way than whole human blood. The whole human blood staine when washed just with a plain, but hot water, will change the color of remains and actually permanently fix the cloth . If water has any contamination ( which any water except distilled will have) possible reactions between the contaminants and blood and plasma components are endless.

  12. Jos Verhulst :What are we to think about the observation reported by Lucotte (“Vérités sur le Saint Suaire”, p.147 ff) on erythrocytes found on the Shroud (microscopic material collected by Giovanni Riggi di Numana) with diameters of 12.5-13 micrometer – much too large a value for human blood, according to this author.

    could have been reticulocytes and there is also a wide variation in the size of erythrocytes as well – especially when the pt is anemic, which is quite a possibility, given the life style and diet.

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