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zumiaq t1_jcjikri wrote

One way would be to simply look at the blood underneath a microscope. If you take a smear of the blood and then stain it with various dyes, blood cells would look different between different species.

The differences would be more extreme the less-related the species. For example, the red blood cells of reptiles and birds still have a nucleus and look like oval eyes. Human red cells, on the other hand, are just red circles-- slightly lighter in the middle than the sides.

Amongst mammals the differences might be a bit more subtle. For example, you might look for a specific type of white blood cell called a eosinophil. They aren't common but if you search the slide you'll probably find one eventually. Eosinophils have a lot of large granules in them that look pretty different from animal to animal.

There are, of course, many many other ways to identify the blood. Some are much more precise than this (genotyping being the obvious one.) But a peripheral smear is low-tech, inexpensive, and I think most fun.

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-Raskyl t1_jckefwj wrote

Replying to [deleted] (#2,251,258)

Ummm.... this isn't true. Iguanas have red blood.

There is a genus of skinks that have green blood. But they are the only lizards I know of that don't bleed red. And technically there blood is red, but has so much biliverdin in it (a byproduct of hemoglobin break down) that it looks green.

Iguanas have been hunted and eaten for hundreds if not thousands of years. They bleed red. You can Google and find pictures of ones with scrapes on their sides, and they are bleeding red. Who told you they bled whatever color they were?

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TheCrafter1205 t1_jckt6ml wrote

The first time forensics was used in a court, a farmer was accused of killing someone, and claimed that the blood on his clothing was pig’s blood. Someone took a sample of the blood, and looked at it under a microscope. Mature human red blood cells do not contain a nucleus, while pig red blood cells do. When he looked under the microscope, there were no nuclei, and this was used to help win the case.

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Chiperoni t1_jckugk7 wrote

You can also pop the cells, collect DNA (from white and red cell precursors and others since mature RBCs don't have it), and sequence it. Then you can compare it to existing databases and chances are you can find a match.

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Impressive_Yam_7717 t1_jcl8y6i wrote

Replying to TheCrafter1205 (#2,254,158)

I feel like this might be inaccurate as pigs are mammals and all mammal RBCs do not contain a nucleus when mature. Maybe it was a chicken as avian RBCs do contain a nucleus. Also, interesting fact camlids (camels, llamas, alpacas, etc) have oval red blood cells.

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WazWaz t1_jclqyke wrote

Easy, inject a little of each into an iguana. The sick/dead iguana got the human blood. Also works in reverse.

Indeed, this is how blood identification works: you inject a little human blood into a chicken, then harvest the antibodies it produces in response. These antibodies can then be used to check if a blood sample is human (eg. only the human blood would react, the antibodies would have no effect on iguana blood).

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TomCollator t1_jclrt75 wrote

Replying to TheCrafter1205 (#2,254,158)

This link suggests a different story.

https://crimereads.com/forensics-on-trial-americas-first-blood-test-expert/

However, young pigs can have a few nucleated blood cells up to age 8 months. As pig are frequently slaughtered around 4-7 months, they can have some nucleated red blood cells.

https://vetclinpathimages.com/2018/03/27/normal-porcine-erythrocytes/#:~:text=Young%20pigs%20(%3C%208%20months%20of,%2C%20and%20Howell%2DJolly%20bodies.

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NOAEL_MABEL t1_jcnk7vi wrote

You could look at its glycosylation. One of the things that makes you unique as a human are your patterns of glycans on your cell surface. For example, only humans and a few other extreme rare out outliers produce sialic acid while all other animals produce hydroxylated sialic acid. The glycome tells you a ton about what species you’re dealing with. You can tell the difference between bacteria vs fungi vs monkey vs fish vs human cells by looking at their sugars alone.

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