WEBVTT 00:00:00.000 --> 00:00:01.800 You know, usually when we talk about a medical 00:00:01.800 --> 00:00:04.339 diagnosis, there's this expectation of, like, 00:00:04.719 --> 00:00:06.860 absolute precision. Oh, absolutely. It's very 00:00:06.860 --> 00:00:08.720 cut and dry. Right. You fall off a ladder, you 00:00:08.720 --> 00:00:10.900 go to the hospital, and the x -ray shows that 00:00:10.900 --> 00:00:13.160 jagged white line on your arm. The doctor just 00:00:13.160 --> 00:00:15.300 points to the screen and says, there's the fracture. 00:00:15.720 --> 00:00:18.219 Yeah, broken or not broken. Exactly. It's binary, 00:00:18.579 --> 00:00:21.460 it's clean, and honestly, it's comforting. We 00:00:21.460 --> 00:00:24.480 really like things to be visible and easily categorized. 00:00:24.620 --> 00:00:26.379 But the thing is, when you step into the world 00:00:26.379 --> 00:00:29.199 of forensic anthropology, suddenly that pristine 00:00:29.199 --> 00:00:32.539 hospital x -ray machine is completely useless. 00:00:32.640 --> 00:00:35.899 You aren't looking at a living patient in a sterile 00:00:35.899 --> 00:00:40.039 room. You might be looking at scattered fragments 00:00:40.039 --> 00:00:43.899 in a forest or a complex mass grave. The diagnostic 00:00:43.899 --> 00:00:47.460 landscape shifts from binary to incredibly murky. 00:00:47.719 --> 00:00:49.719 And that murky landscape is exactly why we're 00:00:49.719 --> 00:00:53.479 here. Welcome to today's Deep Dive. Our mission 00:00:53.479 --> 00:00:56.259 today is to explore the fascinating, intricate, 00:00:56.719 --> 00:00:59.759 and honestly sometimes unsettling world of forensic 00:00:59.759 --> 00:01:02.380 anthropology. It really is a massive topic. It 00:01:02.380 --> 00:01:04.920 is. And we're pulling from a highly comprehensive 00:01:04.920 --> 00:01:08.000 encyclopedia entry that details the history, 00:01:08.299 --> 00:01:10.739 the methods, and the real world applications 00:01:10.739 --> 00:01:13.500 of this field. We want to give you, the listener, 00:01:13.939 --> 00:01:17.280 a shortcut to understanding how scientists actually 00:01:17.280 --> 00:01:20.680 read human remains. Right, pushing way past the 00:01:20.680 --> 00:01:23.540 Hollywood CSI effect to uncover the actual science. 00:01:23.819 --> 00:01:25.780 Exactly, because the premise here is kind of 00:01:25.780 --> 00:01:27.359 mind -blowing when you sit back and think about 00:01:27.359 --> 00:01:30.859 it. Your skeleton is this intricate, constantly 00:01:30.859 --> 00:01:33.939 updating diary of your entire life. But what 00:01:33.939 --> 00:01:35.560 happens when you're no longer around to read 00:01:35.560 --> 00:01:37.780 it? Well, reading that diary when the author 00:01:37.780 --> 00:01:39.560 is gone is essentially the core of the profession. 00:01:39.579 --> 00:01:41.480 And if we connect this to the bigger picture, 00:01:42.060 --> 00:01:44.500 the ultimate goal isn't just, you know, solving 00:01:44.500 --> 00:01:46.540 puzzles for the sake of biological science. It's 00:01:46.540 --> 00:01:48.799 a lot heavier than that. It is. It's about giving 00:01:48.799 --> 00:01:51.980 an identity back to the unrecognizable. We are 00:01:51.980 --> 00:01:54.900 talking about situations where traditional identification... 00:01:54.900 --> 00:01:57.819 Like fingerprints or dental records? Exactly. 00:01:58.019 --> 00:02:00.200 Where those might be completely impossible to 00:02:00.200 --> 00:02:03.400 use. This applies to massive catastrophic events 00:02:03.400 --> 00:02:06.159 like the 9 -11 attacks or plane crashes like 00:02:06.159 --> 00:02:09.319 U .S. Air Flight 427, where the physical impacts 00:02:09.319 --> 00:02:11.919 are just devastating. And it goes beyond accidents, 00:02:11.919 --> 00:02:14.419 right? Yeah. It applies to global tragedies, 00:02:14.560 --> 00:02:17.479 too, like the mass graves in Rwanda or the Srebrenica 00:02:17.479 --> 00:02:20.580 genocide. When the flesh is entirely gone, the 00:02:20.580 --> 00:02:22.759 bones are the absolute last witness available 00:02:22.759 --> 00:02:25.240 to speak for the victims. Wow. OK, let's unpack 00:02:25.240 --> 00:02:28.150 this. Because to understand how modern scientists 00:02:28.150 --> 00:02:30.509 actually give victims their names back today, 00:02:30.909 --> 00:02:32.710 we have to look at how we learn to read that 00:02:32.710 --> 00:02:34.750 skeletal diary in the first place. And it's not 00:02:34.750 --> 00:02:37.710 a pretty history. No, it's really not. The source 00:02:37.710 --> 00:02:39.530 material points out that the foundation of this 00:02:39.530 --> 00:02:42.030 science didn't start with solving crimes. It 00:02:42.030 --> 00:02:43.770 started with something far more controversial 00:02:43.770 --> 00:02:46.129 in the early 20th century. Right, the early pioneers. 00:02:46.689 --> 00:02:48.930 Yeah, you had these physical anthropology pioneers 00:02:48.930 --> 00:02:51.250 like Ernest Houghton and Thomas Wingate Todd. 00:02:51.909 --> 00:02:55.349 In 1912, Todd built this massive baseline collection 00:02:55.349 --> 00:02:59.669 of, I think it was 3 ,300 human skulls and skeletons. 00:02:59.710 --> 00:03:02.229 That's right, over 3 ,000. Just to figure out 00:03:02.229 --> 00:03:04.610 what an average bone looked like. But the question 00:03:04.610 --> 00:03:07.069 is, Why were they so obsessed with measuring 00:03:07.069 --> 00:03:09.289 skulls back then? Well, the initial motivation 00:03:09.289 --> 00:03:11.710 for gathering all that data was heavily tied 00:03:11.710 --> 00:03:14.270 to the cultural and political movements of that 00:03:14.270 --> 00:03:17.189 era, specifically the eugenics movement. Which 00:03:17.189 --> 00:03:20.590 is incredibly dark. It is. Hutton was a major 00:03:20.590 --> 00:03:22.789 proponent of what was called criminal anthropology. 00:03:23.210 --> 00:03:25.909 This was driven by pseudosciences like phrenology 00:03:25.909 --> 00:03:27.969 and physiognomy. Go bump reading stuff, right? 00:03:28.030 --> 00:03:32.069 Exactly. The totally unfounded belief that physical 00:03:32.069 --> 00:03:34.310 characteristics like the shape of your jaw or 00:03:34.310 --> 00:03:37.039 the the bumps on your skull, dictated your moral 00:03:37.039 --> 00:03:40.199 character, or your criminal behavior. So they 00:03:40.199 --> 00:03:41.819 thought they could spot a criminal just by looking 00:03:41.819 --> 00:03:44.759 at their bone structure. Right. The earnest measurement 00:03:44.759 --> 00:03:47.580 of skeletal differences, which is the very foundation 00:03:47.580 --> 00:03:50.500 of anthropometry, was initially fueled by the 00:03:50.500 --> 00:03:53.539 desire to prove these deterministic ideas about 00:03:53.539 --> 00:03:56.120 human behavior. That sounds like a really dark 00:03:56.120 --> 00:03:58.900 beta test of a software program, where the original 00:03:58.900 --> 00:04:02.240 code was just completely corrupted by bias. That's 00:04:02.240 --> 00:04:04.280 a great way to put it. I mean, if the foundational 00:04:04.280 --> 00:04:06.500 data was gathered by people looking to prove 00:04:06.500 --> 00:04:09.639 racist or classist pseudosciences, how did the 00:04:09.639 --> 00:04:12.219 field actually shake off that bias to become 00:04:12.219 --> 00:04:14.800 an objective forensic tool? It took a complete 00:04:14.800 --> 00:04:17.259 change in objective. Instead of trying to predict 00:04:17.259 --> 00:04:19.680 a person's behavior, scientists realized they 00:04:19.680 --> 00:04:21.959 should just be trying to establish their biological 00:04:21.959 --> 00:04:24.740 identity. A shift to actual science. Exactly. 00:04:25.259 --> 00:04:28.480 In the 1940s, a student of Todd's named Wilton 00:04:28.480 --> 00:04:31.980 M. Krugman started actively advertising anthropologist 00:04:31.980 --> 00:04:35.740 skills to the FBI, focusing purely on identification. 00:04:36.669 --> 00:04:39.949 Then, a grim but scientifically pivotal shift 00:04:39.949 --> 00:04:42.389 occurred during the Korean War in the 1950s. 00:04:42.629 --> 00:04:44.589 Because there were so many casualties. Yes. The 00:04:44.589 --> 00:04:46.850 U .S. Army employed anthropologists to identify 00:04:46.850 --> 00:04:49.769 war casualties. And because the military eventually 00:04:49.769 --> 00:04:52.009 knew the confirmed identities of these soldiers 00:04:52.009 --> 00:04:54.449 through dog tags and deployment records, scientists 00:04:54.449 --> 00:04:57.829 had this massive verifiable control group. Oh, 00:04:57.870 --> 00:04:59.870 meaning they could look at a skeleton, guess 00:04:59.870 --> 00:05:01.709 the age and height, and then actually check the 00:05:01.709 --> 00:05:03.509 military file to see if their math was right. 00:05:04.259 --> 00:05:06.779 Precisely. Having that confirmed data allowed 00:05:06.779 --> 00:05:10.199 them to reverse engineer highly accurate mathematical 00:05:10.199 --> 00:05:14.699 formulas for age, sex, and stature based solely 00:05:14.699 --> 00:05:18.000 on the bones. It removed the guesswork. Totally. 00:05:18.519 --> 00:05:20.620 The formulas developed and refined by the Korean 00:05:20.620 --> 00:05:23.980 War data brought extreme objective rigor to the 00:05:23.980 --> 00:05:26.939 field. And they're still the bedrock of the science 00:05:26.939 --> 00:05:30.449 today. By the 1950s and 60s, you see this massive 00:05:30.449 --> 00:05:33.110 breakthrough era. Like with Charles Merbs? Yeah, 00:05:33.329 --> 00:05:35.149 anthropologists like Charles Merbs stepped in 00:05:35.149 --> 00:05:37.209 to help identify the victims of the notorious 00:05:37.209 --> 00:05:40.110 killer Ed Gein, proving that forensic anthropology 00:05:40.110 --> 00:05:42.629 had become a legitimate critical sub -discipline 00:05:42.629 --> 00:05:45.290 for law enforcement. Okay, so out of that wartime 00:05:45.290 --> 00:05:47.930 data, scientists developed a concrete language 00:05:47.930 --> 00:05:50.230 to build a biological profile from nothing but 00:05:50.230 --> 00:05:52.829 bone. Let's look at exactly how they decode that 00:05:52.829 --> 00:05:54.810 language. Let's do it. If an anthropologist finds 00:05:54.810 --> 00:05:57.149 a skeleton in the woods, how do they figure out 00:05:57.149 --> 00:05:59.250 if they're looking at a male or a female? Well, 00:05:59.350 --> 00:06:01.649 the pelvis is the absolute gold standard for 00:06:01.649 --> 00:06:04.110 determining sex. This comes down to the mechanical 00:06:04.110 --> 00:06:06.750 and biological requirements of childbirth. So 00:06:06.750 --> 00:06:09.540 the shapes are noticeably different. Very noticeably, 00:06:10.000 --> 00:06:13.319 a female pelvis has a much wider pubic arch and 00:06:13.319 --> 00:06:16.779 a shorter pushed back sacrum to allow for a birth 00:06:16.779 --> 00:06:20.040 canal. A male pelvis has a narrow pubic arch 00:06:20.040 --> 00:06:23.379 and a longer curved sacrum. But I imagine you 00:06:23.379 --> 00:06:25.579 don't always get a perfectly preserved pelvis 00:06:25.579 --> 00:06:28.439 at a scene. Scavengers might scatter the remains 00:06:28.439 --> 00:06:31.279 or the bones might be crushed. If the pelvis 00:06:31.279 --> 00:06:33.689 is missing, what's the backup plan? They move 00:06:33.689 --> 00:06:36.389 up to the skull. Male skulls generally tend to 00:06:36.389 --> 00:06:39.430 be larger, heavier, and thicker with more pronounced 00:06:39.430 --> 00:06:41.930 muscle attachment sites. Like the brow ridge. 00:06:42.230 --> 00:06:44.689 Exactly. Anthropologists look at specific markers 00:06:44.689 --> 00:06:47.009 like the supraorbital ridge, which is the brow 00:06:47.009 --> 00:06:49.329 bone, and the mastoid process, which is that 00:06:49.329 --> 00:06:51.629 bony bump just behind your ear. But what's really 00:06:51.629 --> 00:06:54.050 fascinating here is the natural variation in 00:06:54.050 --> 00:06:56.410 human biology. Right, because not everyone looks 00:06:56.410 --> 00:06:58.990 exactly the same. Biology isn't a factory assembly 00:06:58.990 --> 00:07:01.730 line. A female might have a naturally narrower 00:07:01.730 --> 00:07:05.449 than average or a male might have a very smooth, 00:07:05.750 --> 00:07:08.410 delicate skull. So they can't just slap a definitive 00:07:08.410 --> 00:07:10.850 male or female label on a bone and call it a 00:07:10.850 --> 00:07:13.350 day. They absolutely cannot. Because of that 00:07:13.350 --> 00:07:16.670 natural biological overlap, forensic anthropologists 00:07:16.670 --> 00:07:19.490 classify sex along a five -point spectrum. Oh, 00:07:19.490 --> 00:07:22.389 really? Five points? Yeah. It goes male, maybe 00:07:22.389 --> 00:07:25.529 male indeterminate, maybe female or female. It's 00:07:25.529 --> 00:07:27.889 a gradient of probability rather than an absolute 00:07:27.889 --> 00:07:29.829 certainty. That makes total sense for adults, 00:07:30.129 --> 00:07:32.750 but what about kids? If you find the remains 00:07:32.750 --> 00:07:35.149 of a child, their bodies haven't gone through 00:07:35.149 --> 00:07:37.889 puberty yet, so the pelvis wouldn't have widened 00:07:37.889 --> 00:07:40.310 for childbirth and the brow ridges wouldn't have 00:07:40.310 --> 00:07:42.910 thickened with testosterone. Right. This is known 00:07:42.910 --> 00:07:45.839 in the field as the puberty problem. Those sexual 00:07:45.839 --> 00:07:48.240 dimorphisms, the physical differences in the 00:07:48.240 --> 00:07:51.060 skeleton between sexes, they're driven by hormones 00:07:51.060 --> 00:07:53.120 that simply aren't present in childhood. So you 00:07:53.120 --> 00:07:55.519 can't use the bones at all? You cannot reliably 00:07:55.519 --> 00:07:57.800 look at a child's skull or pelvis to determine 00:07:57.800 --> 00:08:00.879 their sex. Instead, anthropologists have to look 00:08:00.879 --> 00:08:03.689 closely at the teeth. The teeth? Wait, really? 00:08:04.029 --> 00:08:06.550 Yeah, both sets of teeth, your baby teeth and 00:08:06.550 --> 00:08:09.189 your adult teeth, form well before puberty kicks 00:08:09.189 --> 00:08:11.730 in. On average, male teeth are slightly larger, 00:08:11.870 --> 00:08:14.910 particularly the canine teeth. And males have 00:08:14.910 --> 00:08:17.209 proportionately greater quantities of dentine 00:08:17.209 --> 00:08:19.670 inside the tooth structure compared to females. 00:08:19.930 --> 00:08:22.709 Wow, that is such an elegant workaround. OK, 00:08:22.709 --> 00:08:25.410 so we have sex. Let's talk about stature or height. 00:08:25.850 --> 00:08:28.329 If you just have a pile of bones, how do you 00:08:28.329 --> 00:08:30.110 know how tall the person was when they were walking 00:08:30.110 --> 00:08:32.279 around? It's all about the long bones. Right. 00:08:32.360 --> 00:08:35.000 The leg bones seem obvious. The femur, tibia, 00:08:35.179 --> 00:08:37.860 and fibula. But you can't just stack them up 00:08:37.860 --> 00:08:39.559 on a table and hold a tape measure next to them, 00:08:39.639 --> 00:08:42.480 right? You're missing cartilage, tissue, joints. 00:08:42.840 --> 00:08:46.059 Stature estimation is intense, population -specific 00:08:46.059 --> 00:08:48.759 mathematics. The formulas require knowing the 00:08:48.759 --> 00:08:51.779 individual sex and ancestry first, because limb 00:08:51.779 --> 00:08:54.440 proportions differ significantly across different 00:08:54.440 --> 00:08:57.200 global populations. Ah, so you can't just use 00:08:57.200 --> 00:09:00.299 one universal formula. Exactly. If you apply 00:09:00.299 --> 00:09:02.919 a formula meant for a European male to an Asian 00:09:02.919 --> 00:09:05.460 female, your height estimate will be drastically 00:09:05.460 --> 00:09:07.899 wrong. Once those factors are established, you 00:09:07.899 --> 00:09:10.159 plug the bone length into an equation. Do we 00:09:10.159 --> 00:09:12.559 have an example of the math? Sure. For example, 00:09:12.720 --> 00:09:16.779 a common formula for a male femur is 2 .32 multiplied 00:09:16.779 --> 00:09:19.559 by the length of the femur in centimeters plus 00:09:19.559 --> 00:09:23.159 65 .53 centimeters. OK. So what does this all 00:09:23.159 --> 00:09:26.000 mean when we factor in the reality of human aging? 00:09:26.759 --> 00:09:29.360 Because our bodies don't just stay static once 00:09:29.360 --> 00:09:31.940 we stop growing. Does a forensic anthropologist 00:09:31.940 --> 00:09:33.840 have to account for someone shrinking as they 00:09:33.840 --> 00:09:36.360 get older? They do. And the mechanism behind 00:09:36.360 --> 00:09:39.799 it is fascinating. After about age 30, the cartilage 00:09:39.799 --> 00:09:42.159 discs between your spinal vertebrae slowly begin 00:09:42.159 --> 00:09:44.539 to compress and dehydrate. Which makes us shorter. 00:09:45.100 --> 00:09:47.340 Precisely. Because of this spinal compression, 00:09:47.600 --> 00:09:49.759 a human loses about one centimeter of height 00:09:49.759 --> 00:09:52.480 every single decade. So if you were trying to 00:09:52.480 --> 00:09:54.820 match a skeleton to a missing person's report 00:09:54.820 --> 00:09:57.379 of a 60 year old, you have to account for the 00:09:57.379 --> 00:09:59.519 fact that their skeleton is physically about 00:09:59.519 --> 00:10:01.399 three centimeters shorter than it was when they 00:10:01.399 --> 00:10:04.340 were 30. Which means establishing a highly accurate 00:10:04.340 --> 00:10:07.419 age is absolutely critical or your height math 00:10:07.419 --> 00:10:09.340 is going to be completely thrown off. So how 00:10:09.340 --> 00:10:11.840 do you actually pin down the age of a bone? For 00:10:11.840 --> 00:10:14.759 children and teenagers, it is incredibly precise 00:10:14.759 --> 00:10:17.340 because the skeleton is actively under construction. 00:10:17.669 --> 00:10:20.649 You can check the growth plates, known as epiphysis. 00:10:20.870 --> 00:10:22.850 Are those the ends of the bones? Yeah, they're 00:10:22.850 --> 00:10:25.309 areas of cartilage at the ends of long bones 00:10:25.309 --> 00:10:28.850 where new bone tissue is created. As you age, 00:10:29.049 --> 00:10:32.129 these plates harden and seal shut at very predictable 00:10:32.129 --> 00:10:35.809 intervals. The tibia, or shin bone, seals its 00:10:35.809 --> 00:10:39.529 growth plate around 16 to 19 years old. The clavicle, 00:10:39.669 --> 00:10:42.529 the collarbone, is the very last to seal, usually 00:10:42.529 --> 00:10:45.570 around age 25. You can also simply count the 00:10:45.570 --> 00:10:48.210 bones. Because kids have more bones. Exactly. 00:10:48.529 --> 00:10:51.590 A fully grown adult has 206 bones, but an infant 00:10:51.590 --> 00:10:54.450 has around 300, because many distinct bone segments 00:10:54.450 --> 00:10:57.629 haven't fused together yet. OK, let me put back 00:10:57.629 --> 00:10:59.929 on the adult side of this though. Once you hit 00:10:59.929 --> 00:11:03.629 25 and that collarbone finally fuses, your skeleton 00:11:03.629 --> 00:11:06.309 is basically done growing. Right. If an adult 00:11:06.309 --> 00:11:08.610 skeleton stops hitting those developmental milestones, 00:11:08.909 --> 00:11:11.129 aren't we just guessing their age based on general 00:11:11.129 --> 00:11:12.970 wear and tear? Sounds like trying to guess a 00:11:12.970 --> 00:11:15.370 used car's mileage just by looking at how bald 00:11:15.370 --> 00:11:17.289 the tires are without ever checking the odometer. 00:11:17.549 --> 00:11:20.179 That's a great analogy. If anthropologists were 00:11:20.179 --> 00:11:22.299 only looking at the macro level of the whole 00:11:22.299 --> 00:11:24.019 bone sitting on a table, it would absolutely 00:11:24.019 --> 00:11:26.220 be like guessing mileage based on bald tires. 00:11:27.039 --> 00:11:29.259 They do look at macroscopic wear and tear, like 00:11:29.259 --> 00:11:32.620 osteoarthritis, which causes a noticeable jagged 00:11:32.620 --> 00:11:35.879 rounding of the joint margins over decades. But 00:11:35.879 --> 00:11:38.299 to get past the guesswork and find the odometer, 00:11:38.620 --> 00:11:41.379 they go microscopic. They look at bone osteons. 00:11:41.480 --> 00:11:43.799 Wait, break that down for us. What exactly is 00:11:43.799 --> 00:11:46.740 an osteon? So imagine your compact bone is made 00:11:46.740 --> 00:11:49.539 up of millions of microscopes. cylindrical tubes 00:11:49.539 --> 00:11:52.019 bundled together carrying blood vessels and nerves. 00:11:52.299 --> 00:11:55.440 Like tiny pipes. Exactly. Those tubes are osteons. 00:11:56.019 --> 00:11:58.179 Even after your bones stop growing in length, 00:11:58.279 --> 00:12:00.299 they are constantly remodeling themselves to 00:12:00.299 --> 00:12:03.059 repair microfractures. Specialized cells eat 00:12:03.059 --> 00:12:05.539 away old bone and other cells lay down new bone, 00:12:05.759 --> 00:12:07.480 creating a new osteon. Okay, so how does that 00:12:07.480 --> 00:12:09.740 tell us their age? Under a microscope, you can 00:12:09.740 --> 00:12:12.159 see that younger adults have fewer but much larger 00:12:12.159 --> 00:12:15.539 osteons. As you age, the constant remodeling 00:12:15.539 --> 00:12:18.220 process basically overwrites the old bone again 00:12:18.220 --> 00:12:21.580 and again. So older adults have a chaotic microscopic 00:12:21.580 --> 00:12:24.320 landscape of much smaller, highly fragmented 00:12:24.320 --> 00:12:27.940 osteons. By counting the density and fragmentation 00:12:27.940 --> 00:12:30.659 of these microscopic structures, scientists can 00:12:30.659 --> 00:12:33.440 narrow down an adult's age with incredible accuracy. 00:12:33.539 --> 00:12:35.860 And what's wild is that the sources mention forensic 00:12:35.860 --> 00:12:38.389 anthropology isn't just for the deceased. they 00:12:38.389 --> 00:12:40.990 use this exact same growth plate science on living 00:12:40.990 --> 00:12:43.570 people. They do. Quite often, actually. We see 00:12:43.570 --> 00:12:46.169 this applied to asylum seekers arriving without 00:12:46.169 --> 00:12:48.309 birth certificates or young athletes competing 00:12:48.309 --> 00:12:50.970 in age -restricted tournaments. Medical professionals 00:12:50.970 --> 00:12:54.250 will take hand and wrist x -rays, or use MRIs, 00:12:54.350 --> 00:12:56.610 to look at those specific growth plates and determine 00:12:56.610 --> 00:12:58.590 if the person has crossed a legal biological 00:12:58.590 --> 00:13:00.929 age threshold. It's a very powerful tool. But 00:13:00.929 --> 00:13:03.230 just like reading a used car's history, the bones 00:13:03.230 --> 00:13:05.909 don't give us perfect, flawless answers. The 00:13:05.909 --> 00:13:08.730 diary has missing pages. Every science has its 00:13:08.730 --> 00:13:11.789 limitations, and in forensic anthropology, acknowledging 00:13:11.789 --> 00:13:14.210 those limits is just as important as the discoveries 00:13:14.210 --> 00:13:16.450 themselves. And the most fraught area of the 00:13:16.450 --> 00:13:19.429 biological profile is ancestry estimation. Yeah, 00:13:19.429 --> 00:13:22.250 historically the sources show ancestry was estimated 00:13:22.250 --> 00:13:25.470 by grouping physical traits into three very broad 00:13:25.470 --> 00:13:27.990 categories. Anthropologists would look at the 00:13:27.990 --> 00:13:30.450 shape of the upper jaw, the maxilla. Categorizing 00:13:30.450 --> 00:13:33.830 it as hyperbolic, parabolic, or rounded. Right, 00:13:33.830 --> 00:13:35.870 and they'd try to assign an ancestral origin 00:13:35.870 --> 00:13:38.480 based on that single shape. Today, they measure 00:13:38.480 --> 00:13:41.059 the precise distances between dozens of microscopic 00:13:41.059 --> 00:13:43.460 landmarks on the skull and feed that geometry 00:13:43.460 --> 00:13:46.620 into a computer program called 4DC. Yes, the 00:13:46.620 --> 00:13:49.000 software uses complex algorithms to calculate 00:13:49.000 --> 00:13:51.759 the most likely ancestry based on modern databases. 00:13:52.539 --> 00:13:55.220 But human populations are not static. We are 00:13:55.220 --> 00:13:58.120 a highly mobile, globally intermingling species. 00:13:58.259 --> 00:14:00.539 The genetic lines have blurred. Significantly. 00:14:00.980 --> 00:14:02.879 Which means skeletal morphology has blurred as 00:14:02.879 --> 00:14:05.419 well. And the source material highlights a massive 00:14:05.419 --> 00:14:08.960 red flag regarding that blurring. A major 2009 00:14:08.960 --> 00:14:12.059 study showed that even under favorable circumstances, 00:14:12.460 --> 00:14:15.840 4DC classifications have only a 1 % confidence 00:14:15.840 --> 00:14:19.519 level in some specific cases. One percent? It's 00:14:19.519 --> 00:14:22.220 wild! Imagine if my weather app was only 1 % 00:14:22.220 --> 00:14:24.419 confident it was going to rain. I wouldn't use 00:14:24.419 --> 00:14:27.120 it. I'd throw the phone away. Why do experts 00:14:27.120 --> 00:14:30.360 still rely on a diagnostic tool with such a staggering 00:14:30.360 --> 00:14:32.840 margin for error? Well, this raises an important 00:14:32.840 --> 00:14:35.259 question about how we interpret algorithmic tools 00:14:35.259 --> 00:14:38.100 in forensics. The databases are continually being 00:14:38.100 --> 00:14:40.100 updated with new measurements to reflect modern 00:14:40.100 --> 00:14:43.279 populations, but that 1 % figure demands extreme 00:14:43.279 --> 00:14:45.299 humility from the practitioner. So they don't 00:14:45.299 --> 00:14:47.809 treat it as gospel. Right. It means ancestry 00:14:47.809 --> 00:14:50.429 estimation is definitively the most fragile part 00:14:50.429 --> 00:14:53.149 of the biological profile. Experts don't use 00:14:53.149 --> 00:14:55.250 four to see as a magic eight ball that spits 00:14:55.250 --> 00:14:58.330 out an undeniable truth. They use it as one tiny 00:14:58.330 --> 00:15:01.350 flawed data point among dozens of others. If 00:15:01.350 --> 00:15:03.250 the ancestry data conflicts with the rest of 00:15:03.250 --> 00:15:05.110 the profile, they have to know when to discard 00:15:05.110 --> 00:15:07.649 the algorithm. Another major boundary for an 00:15:07.649 --> 00:15:11.169 anthropologist is trauma. A skeleton clearly 00:15:11.169 --> 00:15:14.149 shows trauma, you know, a cracked skull, a shattered 00:15:14.149 --> 00:15:17.230 rib. But the anthropologist cannot legally or 00:15:17.230 --> 00:15:19.330 scientifically declare a cause of death. No, 00:15:19.350 --> 00:15:21.409 that is strictly the medical examiner's job. 00:15:21.590 --> 00:15:24.370 Right. The anthropologist is only there to identify 00:15:24.370 --> 00:15:26.870 the type of trauma, whether it's blunt force 00:15:26.870 --> 00:15:29.690 from a bat, sharp force from a knife, or a high 00:15:29.690 --> 00:15:32.429 -velocity gunshot wound. Furthermore, their primary 00:15:32.429 --> 00:15:35.070 job regarding trauma is establishing the timeline 00:15:35.070 --> 00:15:38.289 of the injury. They categorize trauma into three 00:15:38.289 --> 00:15:41.730 distinct windows. First is anti -mortem, meaning 00:15:41.730 --> 00:15:44.500 before death. So an injury the person survived. 00:15:44.659 --> 00:15:47.000 Exactly. This is an injury that shows clear signs 00:15:47.000 --> 00:15:49.799 of biological healing. The bone edges will be 00:15:49.799 --> 00:15:51.899 smoothed over or a callus of a new bone will 00:15:51.899 --> 00:15:54.620 have formed. Second is perimortum, meaning the 00:15:54.620 --> 00:15:57.200 injury occurred at or around the exact time of 00:15:57.200 --> 00:15:58.779 death. How do you tell the difference between 00:15:58.779 --> 00:16:01.860 a bone breaking when someone dies versus a bone 00:16:01.860 --> 00:16:04.019 breaking 10 years later when a tractor drives 00:16:04.019 --> 00:16:06.679 over the grave? It comes down to the moisture 00:16:06.679 --> 00:16:10.659 and elasticity of the bone. Living bone, or recently 00:16:10.659 --> 00:16:14.639 deceased bone, is fresh and greasy. A perimortem 00:16:14.639 --> 00:16:17.559 break looks like snapping a green twig. OK, so 00:16:17.559 --> 00:16:19.759 it bends a bit. Yeah. The breaks appear clean 00:16:19.759 --> 00:16:22.940 with rounded margins. And crucially, the discoloration 00:16:22.940 --> 00:16:25.580 of the broken edge perfectly matches the surrounding 00:16:25.580 --> 00:16:28.980 bone. And the third category. Post -mortem breaks. 00:16:29.519 --> 00:16:31.720 These happen long after death when the bone is 00:16:31.720 --> 00:16:34.460 completely dry. Snapping it is like breaking 00:16:34.460 --> 00:16:37.740 a dead brittle branch. The edges are jagged and 00:16:37.740 --> 00:16:39.980 the interior of the break will often be a much 00:16:39.980 --> 00:16:42.100 whiter color because that interior bone hasn't 00:16:42.100 --> 00:16:44.340 been exposed to the dirt and environment for 00:16:44.340 --> 00:16:46.720 nearly as long as the exterior. Let's go back 00:16:46.720 --> 00:16:48.820 to that first category, the anti -mortem trauma. 00:16:49.240 --> 00:16:51.019 The injuries that happened while the person was 00:16:51.019 --> 00:16:53.820 still alive. If you break your arm when you're 00:16:53.820 --> 00:16:56.759 12, does your skeleton keep a permanent record 00:16:56.759 --> 00:16:59.039 of that fracture for the rest of your life? It 00:16:59.039 --> 00:17:02.399 actually does not. Really? Yeah. The window for 00:17:02.399 --> 00:17:04.799 seeing that anti -mortem healing is quite limited. 00:17:05.519 --> 00:17:07.859 Because of that microscopic remodeling process 00:17:07.859 --> 00:17:10.700 we discussed earlier, those osteons constantly 00:17:10.700 --> 00:17:13.880 replacing old bone with new bone, the evidence 00:17:13.880 --> 00:17:16.500 of a healed fracture eventually vanishes. The 00:17:16.500 --> 00:17:18.819 skeleton literally paves right over the trauma. 00:17:18.859 --> 00:17:21.480 It does. After about seven years, a standard 00:17:21.480 --> 00:17:23.720 healed fracture will disappear completely from 00:17:23.720 --> 00:17:27.200 the skeletal record. Wow. Knowing all these intricate 00:17:27.200 --> 00:17:29.579 details about trauma interpretation brings up 00:17:29.579 --> 00:17:32.500 a massive ethical and procedural risk in the 00:17:32.500 --> 00:17:35.220 field, confirmation bias. It's a huge problem. 00:17:35.420 --> 00:17:37.880 If a forensic anthropologist is told the context 00:17:37.880 --> 00:17:40.559 of a complex case before they look at the bones, 00:17:41.079 --> 00:17:43.400 say, an eager detective tells them, hey, we are 00:17:43.400 --> 00:17:45.200 absolutely certain the suspect used a hammer. 00:17:45.769 --> 00:17:48.329 it can inadvertently warp their scientific analysis. 00:17:48.369 --> 00:17:50.589 So consciously, yeah. The anthropologist might 00:17:50.589 --> 00:17:52.329 start seeing the specific characteristics of 00:17:52.329 --> 00:17:55.029 a hammer strike in the fracture patterns, ignoring 00:17:55.029 --> 00:17:57.490 alternative possibilities. Right. And because 00:17:57.490 --> 00:17:59.990 of those innate biases and the strict limitations 00:17:59.990 --> 00:18:02.869 of the bones themselves, anthropologists cannot 00:18:02.869 --> 00:18:05.869 just look at a body in a sterile vacuum. To get 00:18:05.869 --> 00:18:08.150 the whole truth, they have to leave the laboratory 00:18:08.150 --> 00:18:10.069 and look at the dirt around the bones. Which 00:18:10.069 --> 00:18:12.589 brings us into the subfield of forensic archaeology. 00:18:12.730 --> 00:18:15.630 Yes. And to be clear, forensic archaeology is 00:18:15.630 --> 00:18:18.269 not just using tiny brushes to sweep away dust 00:18:18.269 --> 00:18:20.660 from a perfectly laid out skeleton. like you 00:18:20.660 --> 00:18:23.519 see in museum documentaries. No, it requires 00:18:23.519 --> 00:18:27.640 radical, real -time adaptability. The text details 00:18:27.640 --> 00:18:30.599 a specific case study of a missing girl whose 00:18:30.599 --> 00:18:33.500 remains were ultimately found submerged in an 00:18:33.500 --> 00:18:35.900 underground septic tank. Oh wow, that's incredibly 00:18:35.900 --> 00:18:39.819 grim. It is. And you simply cannot use standard, 00:18:40.059 --> 00:18:42.259 grid -based archaeological trenching methods 00:18:42.259 --> 00:18:44.819 in a confined space filled with liquid sludge. 00:18:45.380 --> 00:18:47.859 The anthropologists had to invent entirely new, 00:18:48.099 --> 00:18:50.519 forensically acceptable ways to pump, filter, 00:18:50.740 --> 00:18:53.119 and preserve the contents of that tank without 00:18:53.119 --> 00:18:55.500 destroying the fragile evidence suspended inside 00:18:55.500 --> 00:18:57.500 it. It's all about reading the context of the 00:18:57.500 --> 00:18:59.740 environment. When investigators are looking for 00:18:59.740 --> 00:19:02.920 a hidden clandestine grave in a forest, they're 00:19:02.920 --> 00:19:05.920 basically reading the soil. When a body decomposes, 00:19:06.480 --> 00:19:08.740 it releases a massive flush of nutrients into 00:19:08.740 --> 00:19:11.930 the earth. The soil in a grave becomes looser, 00:19:12.230 --> 00:19:15.450 darker, and much more organic. It actually causes 00:19:15.450 --> 00:19:17.690 a visible difference in the vegetation on the 00:19:17.690 --> 00:19:20.250 surface. Yeah, certain weeds will explode and 00:19:20.250 --> 00:19:23.029 growth directly over the grave while the surrounding 00:19:23.029 --> 00:19:25.390 plants look completely different. Finding and 00:19:25.390 --> 00:19:27.630 excavating these sites, especially when dealing 00:19:27.630 --> 00:19:30.650 with international mass graves, introduces deep 00:19:30.650 --> 00:19:33.509 ethical complexities into the science. The source 00:19:33.509 --> 00:19:36.230 material notes a profound tension in these operations. 00:19:36.529 --> 00:19:39.089 It's a very difficult balance. On one side, you 00:19:39.089 --> 00:19:41.890 have large international organizations that often 00:19:41.890 --> 00:19:45.069 want to exhume these graves to meticulously gather 00:19:45.069 --> 00:19:47.730 evidence for criminal prosecution and the global 00:19:47.730 --> 00:19:50.269 exposure of war crimes. Right. For justice. But 00:19:50.269 --> 00:19:53.250 on the other side, smaller Local human rights 00:19:53.250 --> 00:19:56.190 groups sometimes strongly oppose exhumation. 00:19:56.670 --> 00:19:58.710 Their concern is that digging up the dead reduces 00:19:58.710 --> 00:20:01.670 the victims to mere forensic evidence, overshadowing 00:20:01.670 --> 00:20:04.230 their identities and their lives with the violent 00:20:04.230 --> 00:20:06.970 clinical nature of their deaths. It is a very 00:20:06.970 --> 00:20:09.829 delicate ethical divide that field archaeologists 00:20:09.829 --> 00:20:12.369 must navigate with immense cultural sensitivity. 00:20:12.769 --> 00:20:14.890 We are just reporting on this tension, but it's 00:20:14.890 --> 00:20:17.250 clearly a massive part of the job. Navigating 00:20:17.250 --> 00:20:19.970 the reality of what happens in that soil leads 00:20:19.970 --> 00:20:23.329 us to our final core concept. Forensic typhonomy. 00:20:24.089 --> 00:20:26.910 This is the intensive study of postmortem environmental 00:20:26.910 --> 00:20:29.690 changes. Basically what happens to the body from 00:20:29.690 --> 00:20:31.650 the moment of death to the moment of discovery. 00:20:31.950 --> 00:20:34.450 And to study this accurately, researchers use 00:20:34.450 --> 00:20:37.529 facilities commonly known as body farms, pioneered 00:20:37.529 --> 00:20:40.599 by anthropologist William M. Bass. These are 00:20:40.599 --> 00:20:43.680 secure outdoor laboratories where donated human 00:20:43.680 --> 00:20:45.839 cadavers are placed in various environmental 00:20:45.839 --> 00:20:49.000 conditions so scientists can precisely monitor 00:20:49.000 --> 00:20:52.039 the stages of decomposition. Tofonomy is conceptually 00:20:52.039 --> 00:20:54.819 divided into two distinct interactive branches. 00:20:55.099 --> 00:20:57.299 First is bio -tofonomy. Which looks at how the 00:20:57.299 --> 00:20:59.220 environment affects the body. Right. Variables 00:20:59.220 --> 00:21:02.200 like how a humid climate accelerates decay, how 00:21:02.200 --> 00:21:04.460 specific local animals or insects scavenge the 00:21:04.460 --> 00:21:07.359 remains, or even how internal factors like embalming 00:21:07.359 --> 00:21:09.950 fluids or chronic diseases alter the decomposition 00:21:09.950 --> 00:21:12.390 timeline. And the second branch is geotaphonomy, 00:21:12.609 --> 00:21:14.769 which flips the perspective entirely. And here's 00:21:14.769 --> 00:21:17.289 where it gets really interesting. We usually 00:21:17.289 --> 00:21:20.250 think of decomposition as a strictly destructive 00:21:20.250 --> 00:21:24.609 process. Flesh decays, identifying markers are 00:21:24.609 --> 00:21:27.569 lost, the elements wash things away. But looking 00:21:27.569 --> 00:21:30.130 at geotaphonomy, it sounds like a decaying body 00:21:30.130 --> 00:21:32.730 isn't just disappearing, it's actively creating 00:21:32.730 --> 00:21:36.089 brand new evidence in the soil. That is precisely 00:21:36.089 --> 00:21:39.400 the paradigm shift. The body acts as an intense 00:21:39.400 --> 00:21:42.700 chemical agent. It dramatically alters the pH 00:21:42.700 --> 00:21:45.599 levels of the soil beneath it. It acts as a dark 00:21:45.599 --> 00:21:48.880 fertilizer that accelerates or decelerates specific 00:21:48.880 --> 00:21:51.079 root growth. That's incredible. As the body breaks 00:21:51.079 --> 00:21:53.440 down, it physically disturbs the microscopic 00:21:53.440 --> 00:21:56.000 geological layers of the earth beneath it. By 00:21:56.000 --> 00:21:58.420 examining those permanent environmental changes, 00:21:58.980 --> 00:22:01.339 scientists can build a definitive chronological 00:22:01.339 --> 00:22:03.400 timeline of events. So they can tell what happened 00:22:03.400 --> 00:22:05.859 and when. Exactly. They can read the dirt to 00:22:05.859 --> 00:22:07.880 determine if scattered remains were moved by 00:22:07.880 --> 00:22:10.480 coyotes weeks after death or if they were deliberately 00:22:10.480 --> 00:22:12.680 relocated by a killer trying to hide their tracks. 00:22:13.140 --> 00:22:15.019 The destruction of the biological body creates 00:22:15.019 --> 00:22:17.420 a permanent readable scar on the earth itself. 00:22:17.900 --> 00:22:19.559 Understanding that our skeletons aren't just 00:22:19.559 --> 00:22:21.819 static scaffolding holding us up, it's completely 00:22:21.819 --> 00:22:24.640 paradigm shifting. They're incredibly dynamic 00:22:24.640 --> 00:22:27.019 records. They interact with our environment while 00:22:27.019 --> 00:22:29.579 we are alive and they continue to alter the earth 00:22:29.579 --> 00:22:32.319 around them. holding onto secrets long after 00:22:32.319 --> 00:22:34.740 the flesh is gone. It really forces you to view 00:22:34.740 --> 00:22:36.640 the human body through a completely different 00:22:36.640 --> 00:22:40.259 lens. And it leaves us with something quite profound 00:22:40.259 --> 00:22:43.240 to consider, branching off from everything we've 00:22:43.240 --> 00:22:45.769 explored today. Let's hear it. We learned that 00:22:45.769 --> 00:22:48.549 through the microscopic remodeling of osteons, 00:22:48.910 --> 00:22:50.950 bones completely lose the evidence of trauma 00:22:50.950 --> 00:22:53.769 and healed fractures after seven years. We learned 00:22:53.769 --> 00:22:56.430 that due to spinal compression, we lose a centimeter 00:22:56.430 --> 00:22:59.890 of height every decade after our 30s. Our skeletons 00:22:59.890 --> 00:23:02.109 are constantly erasing their own past to build 00:23:02.109 --> 00:23:05.349 our present. If the ultimate biological witness 00:23:05.349 --> 00:23:07.970 in a legal setting, our own bones, has a built 00:23:07.970 --> 00:23:10.069 -in biological expiration date for the truth, 00:23:10.289 --> 00:23:12.349 what does that mean for our pursuit of justice 00:23:12.349 --> 00:23:15.019 decades after a crime is committed? A built -in 00:23:15.019 --> 00:23:17.319 expiration date for the truth. If the diary is 00:23:17.319 --> 00:23:19.259 constantly overwriting itself, you have to wonder 00:23:19.259 --> 00:23:22.039 what chapters we've already lost. Something for 00:23:22.039 --> 00:23:24.380 all of you to chew on as you go about your reek. 00:23:24.640 --> 00:23:27.059 Keep questioning the world around you. Keep looking 00:23:27.059 --> 00:23:29.420 beneath the surface. And thanks for joining us 00:23:29.420 --> 00:23:30.180 on this deep dive.