Science Friday - Brain Donation, Meat And Human Evolution, Bird Song, Space Station Retirement. Feb 4, 2022, Part 1

Episode Date: February 4, 2022

Date Set For International Space Station’s Burial At Sea The International Space Station was never going to last forever. And its expiration date had already been moved from 2024 to 2030. But NASA finally released the plan for what happens after the end of United States support for the orbiting research lab. In a report released this week, NASA announced the station, once decommissioned, would orbit into the ocean in 2031. More specifically, it would end at a place between New Zealand and the southern tip of South America called “Point Nemo”—a final resting place for other spacecraft chosen because it is the place on Earth farthest from land masses. Science journalist Maggie Koerth joins Ira to explain the end of the ISS and other stories, including two black holes that may or may not exist and may or may not collide, the U.S. Geological Survey’s effort to monitor a sleeping volcano, what we’re learning from COVID-19 “challenge” trials and a centuries-old act of resistance against colonial forces.   Why Should You Donate Your Brain To Science? Ever wonder what happens after you donate your brain to science? If you have a disease or disorder like Alzheimer’s, Parkinson’s, autism, traumatic brain injuries, depression, it can be used to help researchers better understand the condition and potentially lead to new treatments. But scientists also need to study the brains of people unaffected by any type of disease. Ira is joined by Dr. Bill Scott, executive director of the University of Miami’s Brain Endowment Bank, based in Miami, Florida, and Tish Hevel, CEO of the Brain Donor Project, based in Naples, Florida, to discuss what scientists can learn from studying human brains and how to donate your brain to science after you’re gone.   Eating Meat May Not Have Spurred Human Evolution Scientists have long theorized that meat is what made us human. The idea was that about two million years ago, an early human ancestor emerged. Homo erectus had a bigger brain, longer legs, and a smaller gut than modern humans, but they were more like us than apes. The cause of these big evolutionary changes, researchers hypothesized, was eating more meat. Now, after re-analyzing fossil records, some are beginning to question the assertion that meat-eating was the primary driver of changes during this pivotal point in human evolution. Ira is joined by the study’s co-author, Briana Pobiner, a paleoanthropologist at the Smithsonian National Museum of Natural History, based in Washington, DC.   The World According To Sound: How Do Songbirds Sing Two Notes At Once? Humans can talk because of their larynx, an organ shared by all mammals. Birds also have a larynx, but they use a different organ to vocalize: a syrinx. The syrinx is a complex and powerful voice-box. Unlike the larynx, it allows birds to do things like sing two different notes at the same time. That’s how some song birds can sing an ascending line and descending line simultaneously. Even with all the possibilities of their syrinx, some birds have adapted other ways to “sing.” The Ruffed Grouse, for instance, uses its wings. The Wilson’s Snipe makes a song with its wings and tail. The Palm Cockatoo holds a stick in its beak and bangs it on a tree. The Magnificent Frigatebird inflates its throat sacs and beats them with its long beak. The Sage Grouse makes its song with special chest sacs.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Iroflato. Later in the hour, we'll talk about how researchers are using donated brains, just like yours, yeah, to understand conditions like Alzheimer's, Parkinson's, and even depression. But first, it's orbited above us for decades. It's a valuable tool for scientific research. And in 2013, it will crash into the sea. I'm talking about the International Space Station. The aging station, NASA reported this week, has a set expiration.

date and will join a sorted spacecraft from history, including the Russian Space Station Mir and Skylab in a watery ocean grave. Here with this and other selected short subjects in science is Maggie Kerth, Senior Science Writer for 538. Welcome back, Maggie. Hi, thanks for having me. You're welcome. So why are we losing the ISS in 2031? Mostly because it is a 20-plus-year-old piece of spacecraft that is not going to be in good working order for a whole lot longer than that. The NASA and the Biden administration have decided that they want to keep it flying until 2030, which would extend its life by an extra six years from where it's currently set. They still need to get some sign-offs from that to make that plan happen, though,

both from Congress and from Russia and from a bunch of other international partners. But it could end up meaning that the old girl is with us just a little bit longer. And they have a place that they're aiming for to bring it down, right? A very famous place. They do. It is called Point Nemo. It's Greek for no man, which is very apt because it is the spot in the Pacific Ocean that's optimized to be the furthest from land that you can get anywhere on Earth. It's more than 1,600 miles from the nearest land. The astronauts who are currently aboard the space station are often, the closest humans to Point Nemo as they pass overhead in orbit. So over the years, like you said, this Point Nemo has turned into a popular retirement home for spacecraft. And the deal is that, like, nobody wants to have to worry about what or who craft might hit as they land. So we land them in this place where there's nothing really at all, like not even that many

fish. That's because the Point Nemo is in the middle of a gyre. So it's this location in the ocean where currents kind of move in a circular pattern. So you don't even get very many new nutrients flowing in. There's not a lot of plants or fish even in this area, which is probably a really good thing because there's a lot of environmental concerns, actually, around dumping space junk into the ocean. These are things that can leak toxic hydrazine rocket fuel and also radioactive chemicals. Wow. Yeah. It's interesting that you can actually pick the spot where you wanted to land. It super is. One other thing that I found about this that maybe you'll enjoy is that the ocean may perhaps someday have its revenge. In 1928, years before anybody started dumping rockets there,

H.P. Lovecraft had identified this general area as the location where Cthulu lies sleeping. Whoa. Think about that for a while. Let's go elsewhere. Let's go elsewhere. Let's go elsewhere. we're in space. There are two black holes that may be about to merge. Maybe. This is such a great story. I love this so much. So at the center of the galaxy, 1.2 million light years from Earth, there are two gigantic black holes that are about to crash into each other. This event could release a huge burst of light, surges of gravitational waves and neutrinos, and it would give scientists a chance to witness something that's previously only been theorized. It could happen in as soon as just a hundred days. Or it might not happen at all.

and also the black holes might not exist. Wait a minute. Wait a minute. That covers all the bases, doesn't it? It sure does. You know, welcome to the wonderful world of interstellar astronomy. You know, there's so many things that we can't see directly. And what scientists do when they can't see things directly is they make assumptions based on kind of all of these things that they can measure. And in this case, what they've spotted is not too.

supermassive black holes, it's this galaxy with a bright shining center that dims and glows. This effect is something that some scientists have theorized would be caused by two black holes orbiting each other very closely, sucking in and heating surrounding matter and this kind of churning oscillation. And the fact that the oscillation periods are getting shorter suggests that the black holes, if they do exist, might be getting closer to each other. there is no way to know in advance what is actually happening. The scientists who think this is going to happen think that it will happen somewhere between 100 to 300 days from now.

So scientists are jockeying for telescope time in that range. You know, people are getting poised to be ready for it in case it does happen. Because if it does, there would be a whole bunch of signals that show up and everyone in science will go wild. Like this will be in a really super amazing thing. Or we'll all just spend the next year sitting around and nothing happens and nothing continues to happen. Wow. Let's turn to something that is really very interesting and a bit more serious.

And this is a story about indigenous sovereignty, resistance to colonization in South America hundreds of years ago. Tell us about this mortuary rebellion, as it's called. Yeah, so some 500 years ago, people living on what's now the southwestern coast of Peru began to take human spinal columns and thread them onto reeds, one vertebra at a time. The collections look a little bit like creepy rhythm instruments, but archaeologists think these spines are actually a way for people to reclaim their ancestors and rebel against Spanish imperialism. There's a lot of good reasons why the scientists think that.

it's kind of this accumulation of evidence over time. So here's some of the evidence. The researchers already knew that people of the ancient Chincha kingdom venerated their dead. They made mummies. They interred them in these stone towers. And these stone towers are where many of these vertebrae on sticks are found. Scientists also knew that when the Spanish arrived, the colonizers tried to wipe out this ancestor veneration because they thought it was idolatry.

so they were desecrating bodies and they were robbing tombs. And there are known cases where the native Jincha people were coming back later in the wake of the Spanish destruction and building themselves new effigies of their loved ones from scraps of hair and fingernails that had been left behind. But the real clincher here is dates. So this new study performed radiocarbon dating on three bones and nine of the reeds. and they found that the bones were coming from people who died between 1520 and 1550, which is a time when there were just massive numbers of chinch of people being killed by starvation, disease, directly by the Spanish. And the reeds, meanwhile, were picked as much as 40 years later. So, like, this just, well, this hit me really hard because you can almost imagine a grown child coming back and piecing together all that remained of a parent they'd lost years before.

So these vertebrae may have been how colonized people were resisting conquest by continuing to mourn their dead, right? By continuing to honor their dead and have their dead with them in ways that celebrated their dead and made their ancestors a part of their family. Let me just add that the image of these bones are really, really powerful, and we've linked to it, that image on our website if folks are curious to see what we're talking about. Your next story is about a volcano stirring in Oregon. Should folks be worrying, Maggie? No, that's the good news. You're fine. So this is really interesting, though.

Like even though it is not an emergency situation, I think it's worth paying attention to because it's really cool. Because 20 years ago, scientists were watching this mountain, South Sister, an Oregon volcano, kind of changing in ways that suggested there was activity, happening underground in its magma chambers. You were getting bulging on its slopes. There were tiny earthquakes. And then in around 2001, the changes just stopped. And for two decades, South Sister sat there, silent and immobile. And now she's moving again. So just to give you some sense of scale, in the months before Mount St. Helens erupted in 1980, the side of that mountain bulged out

hundreds of feet. And in contrast, over the span of, you know, 1995 to 2001, South Sister bulged five inches. This is a much smaller, much smaller scale of changes. And that's actually what makes it cool because what this represents is how much work has gone into learning how to monitor these kind of volcanoes in minute detail. You know, we are getting data back about changes that nobody maybe even would have noticed. 40 years ago. So now we have this satellite imagery and we have these highly sensitive seismometers that can spot earthquakes that are less than, you know, less than magnitude one. And we are learning about what it looks like when a volcano sort of mumbles in its sleep. And that helps scientists

better understand, you know, what to watch for and what changes actually are concerning. Cool. Cool. Cool story. A last story we have is a bit of COVID-19. news, there's now finally a chance for those of us who have been lucky enough to escape the virus to get deliberately infected. Do it for science, right? Do it for science. Yeah, the world's first COVID challenge trial is seeking a new round of volunteers who would have samples of virus inserted into their noses so that scientists can learn things like how much virus it takes to trigger an infection and what kind of immune responses are necessary to fight one off. Now, these are not anything new as a kind of trial.

Scientists have done this kind of study before, but just with different kinds of pathogens. This is just the first time we're doing it with COVID. And when they do these trials, in this case and in the past, they're often a way of understanding infection on a much more detailed basis than you can do with like a natural infection so that you can make better vaccines. They've done this with cholera, flu, and dengue fever, and a whole bunch of other things. This particular trial has had a couple of studies published already. One of them involved 36, 18 to 29-year-olds who were exposed to droplets of COVID virus.

18 became infected. 16 developed cold-like symptoms. 13. Temporally lost smell and taste. The researchers were working in that case on figuring out the lowest possible amount of COVID you could expose someone to and still infect them. And that knowledge is now going to help them better perform this next round of experiments, which are aimed at figuring out what level of antibodies and T cells are needed to prevent infection. And that information is going to help

scientists design better, more effective vaccines in the future. Thank you, Maggie. Maggie, it was great having you on again. Great stories. Yeah, thank you. Maggie Kerth, senior science writer for 538. She was joining us from Minneapolis. After the break, have you ever wondered what happens if you donate your brain to science? This is Science Friday. I'm I replato. This next interview was recorded in front of a live Zoom audience. To find out more about our Zoom call-in events, you can go to Sciencefriday.com slash live stream. And now, on with the show.

Do you ever wonder what happens if you donate your brain to science? Well, it can be used to help researchers better understand and treat our own. all types of diseases and disorders, like Alzheimer's, Parkinson's, autism, traumatic brain injuries and depression, but researchers also need to study the brains of people unaffected by any type of disease. To help us better understand what scientists can learn from studying human brains and how to donate your brain to science after you're gone are my guest, Dr. Bill Scott, Executive Director of the University of Miami's Brain Endowment Bank based in Miami, and to donate. Tish Hevel, CEO of the Brain Donor Project, based in Naples, Florida.

Welcome to Science Friday. Thank you. Glad to be here. Well, let me go right to the questions. Dr. Scott, so there's a clear need for people who have rare brain disease or neurogenitive disorders or mental health diagnoses. We understand there's a need for them to donate their brains to science. What about if you don't have any specific brain disorder?

Can our brains still help? Absolutely. And in fact, we need people of all kinds to donate their brains for scientific research. Because every time we want to understand what's going on with a particular disease or condition, we have to have brains to compare it to. So if I want to understand why some people with Alzheimer's disease have certain types of symptoms, I can compare them to other people with Alzheimer's disease, and that tells me something. But what I really want to know is what's very, very different between somebody that doesn't have

Alzheimer's disease, what protects them from developing Alzheimer's disease, and what makes somebody else more likely to develop it. And you can use any condition that involves the brain in that example and we always need a comparison group. And so anyone, regardless of what your brain is like, can donate your brain for research and it would be useful. Tish, I understand you actually have brought a human brain with you this evening. I have. And this is an interesting one for a few reasons. I'm being very careful. This is the brain of a man who died when he was 101 years old, and he was said to be very astute right up until the time he died. I'm also told by the scientists that his brain is larger than what is typical for a man his age. So yeah, this is his brain, which is, I feel so

reverent about this because the tissue is so precious. A lot of people, and in some states on driver's licenses will say, you know, this is an organ donor. Is the brain part of the organ donor program? Yeah, it is not part of an organ donor program where people are consented to donate organs to transplant. We don't transplant brains. And it doesn't automatically mean that somebody who's registered with one of those programs will be asked if they want to donate their brains for research purposes. Some states will and other states will not. Now, sometimes what will happen is somebody will be asked at the moment that someone has died and it's noted that they're an organ donor, if they're unable to donate their organs for one reasons or another, they may be asked, well, do you want to

participate in a research project or donate tissue for transplant? And then we will wind up getting a referral from that organ donor agency saying, here's somebody that you might want to talk to. But it doesn't happen as often as we'd like. We would really like for people to be considering this ahead of time so that you can have that conversation with your loved ones and indicate that your desire is to donate your brain in addition to donating your organs for transplant because you can sometimes do that. And sometimes making those wishes known will allow you to donate something if you cannot donate your organs. As Bill said, it's not automatic. In fact, it's very rare. I think your brain bank is one of the exceptions that work so closely with the organ

procurement organization. So the other one is people who've signed up to be an anatomical body donor, usually to a local medical school. Yes, they're getting your brain, but no, they're not using it for neuroscience research. And scientists all agree that the brain is so much more valuable for neuroscience research than it is for anatomic study. People are concerned. People are concerned also that it's disfiguring and it isn't. The brain is removed through the back of the head, so an open casket is so very much an option. And then the final thing is, is there an additional cost? And you'll all be pleased to know that there is not when you donate through one of the NIH's brain banks. The NIH knows this is the most precious tissue for neuroscience research. And so they reimburse people

along the way to be able to acquire it. Well, what do I do if I'm listening to this program now, and you have motivated me to donate my brain? What's the ABC? What are the steps? So we sort of function as the intake arm for the neurobiobobank, which is the structure of the NIH's brain banks. We send everybody to our website, which is at braindonorproject.org.

You can learn more about brain donation, about the process, how badly they're needed. and when you're ready, there's a little brain pre-registration button in the upper right-hand corner. That will take you to a very brief online form. Once you hit submit, we're able then to make a decision about which of those brain banks makes the most sense for that person and connect that person or his or her family to the brain bank. So at that point, we sort of hand off the relationship to the brain bank, and then they proceed with the second set of registration forms,

talking to the family and letting them know what to expect at time of death. Now, Dr. Scott, let's walk through the ABCs of what happens to the brains. I know that the brain bank you run at the University of Miami is part of a network of brain banks across the country, right? Run by the NIH called the Neurobiobank. Tell me about the network, the brain banks. What happens when a brain gets to a bank and makes a deposit, so to speak? So one of the things that I like to say is that, that the Brain Endowment Bank at the University of Miami specifically chose to have that

endowment in the middle of our name because it's like the endowment of a university where you're making a gift for a resource that will fund or enable work that we do with these brains long into the future. So it's a bequest that we're receiving. And so once we get the notice that somebody wants to donate the brain. We organize the effort to coordinate the recovery of the brain at the time of death. This can take place anywhere in the country where we have a network of pathologists and technicians that work to do this work. The brain then gets put on ice and sent to the closest bank. So that's one of the reasons why we have this network so that we can have something that is a little closer to most donors. And then when it arrives, we will take it and we will

dissect it so that it can be used for many different projects. So we'll divide the brain in half. We'll put one half of it into a fixative, which most of you would know as formaldehyde. We call it formalin most of the time. And that preserves it so that we can look at the structure of the tissue. And then we take the other part of the brain, we will slice the half of the brain so that we then have smaller sections that can be frozen. And that preserves the brain in a way that it can be used in different kinds of experiments from the fixed part. So we can use that to look at proteins and DNA and RNA and the different structures within the brain to see how cells change. and those get stored in different places. The fixed tissue goes into a container that stays in a cool room like a refrigerator.

And the frozen tissue goes into a very low temperature freezer. And every brain bank has a slight variation on this, but we all basically have the same structure, a place where we can receive the brain and dissect it and places where we can store it so that we can then pull it out and share it with investigators when they meet it. How does an investigator make a withdrawal from the bank? Do they come to you with a project and you okay it? I mean, how does that system work? Most brain banks use a similar system and the neurobiobank is no different. There is a web-based portal where investigators can go and make a request. They describe the study they want to do. They tell us what they would do with the tissue and how much they need.

And then it goes through a review process to make sure that, yes, the science actually would benefit from the use of this resource. It's a limited resource. So we make sure that the tissue is being used scientifically appropriately. And then as long as those criteria met, a recipient or requesting scientist can be sent those samples for use in their lab. And the NIH supports that. Other brain banks that exist under other models have other ways of requesting tissue. Sometimes the samples are only made available if you're working on a certain type of project or you're at a certain institution or part of a bigger network. Tish, how did you get involved in this?

My dad had dementia and he was at the point where he was diagnosed with suspected Louis Bodies dementia. We weren't familiar. So in our Googling and trying to research what that was about, about we came across the idea of brain donation online because, you know, researchers thought they were on to something at that point and they needed it. So we made arrangements to donate my dad's brain and it was very, very complicated at the time. In those days, the neurobiobionk was brand new, really, so they just hadn't had a chance to do all this yet. So we made arrangements to donate his brain. We thought it was complicated and then we got in touch with the National Institute of

neurologic disorders and stroke and said, can we help you with this? And Dr. Corrischetz put me in touch with the women who run the brain bank and we got it started. I'll tell you, and this is going to sound corny, but hang with me, there was a palpable sense of comfort that we all felt in my family and other people have told me about this as well, just knowing that there's a really good chance that something positive can come from this horrible loss. You know, maybe another family down the road won't have to suffer watching, you know, their loved one past because we'll learn some stuff from this. But the second thing is even more interesting, especially in neurodegenerative cases like the dementias and Parkinson's. As part of being a brain donor family, the brain bank

will provide, also at no cost, a copy of a really enlightening report, and that is called a summary of neuropathological findings. That told us, and it tells anybody, Here's the diseases that were found in your loved one's brain. Here's the stage of the disease, the regions of the brain that were impacted. So, you know, in many cases, that's the only definitive diagnosis you'll get. So now when we learn more about some of these neurodegenerative diseases, that'll be valuable to the rest of us, his children and family, to know how inheritable that is. Bill, I have to ask this question because we are in an age of very sophisticated technology

to look at the brain. We have MRIs, CT scans. How much usage does an actual tissue have as opposed to getting a scan of someone's brain? Well, it's important to be able to understand those images that we get from MRI and CT in the context of what's going on. in the actual tissue of the brain. So we can see patterns on those images, and we need to compare them to the pathology that exists in those same individuals so that we can understand what those images truly mean. Also, there's no substitute for looking at a protein inside a cell inside a tissue to understand why biologically something might be occurring.

So in my own work, as a genetic epidemiologist, one of the questions we often struggle to answer is, why is there a particular variant that's associated with a disease responsible for the symptoms of the disease? What's going on biologically? Because you don't necessarily know from just knowing what the change in the DNA is. But if we can then go in to brain tissue from people that carry that same variant, who had the disease and look at what was going on with the proteins inside the cells, did the structure of the brain change, that is something that you can really still best see by looking at brain tissue and not always does it show up on imaging.

And in fact, it's by looking at some of the brain tissue, we can then map it back to images so that we can then in other people look at images and interpret it in the context of what we know from brain pathology. This is Science Friday from WNYC Studios. Let's go out to the audience. Monica has a question about how to talk with her family about brain donation. Welcome, Monica, to Science Friday. Hi, thank you.

So my question is, if I have a family member, she has a neurological condition. and has been asked to donate her brain to the Brain Bank at Northwestern University in Chicago. She's getting to do it, and I want to support her in that. But what are the sort of questions or concerns from family or friends that I can anticipate and how should I respond to those in order to support this idea? That's a good question. A lot of people are concerned that it will interfere somehow with funeral plans or slow down that process. It doesn't, since the brain needs to be removed and hopefully stored safely

back at the brain bank well within 18 to 24 hours. You know, I think people used to be a little, I'll use the scientific word hinkier about brain donation and what happens to our parts after we die than they are now. My experience has been once people have a good understanding of how critical the need is for this tissue of how we're not going to get to the next set of breakthroughs without it, or at least not fast enough, then a lot of the objections they might have seem to just fall away. You know, when they know they're doing something important as heck to advance science, so many people are like, hey, if it can help somebody on my way out the door, I'm fine, I'm finished.

Some of the most cutting edge neuroscience research is a project that is cataloging, if I understand it, every neuron in the brain as part of NIH as a brain initiative. How are researchers using data from brain banks to do this? The brain initiative is touching all parts of NIH research and the neurobiobank is a partner. We are participating in a project that is starting this year that is creating a brain cell atlas. Our mission as the brain bank bank, coordinators is to identify enough people who fit that criteria we talked about before of neurotypical controls from across the age span and from all different kinds of racial, ethnic, and demographic groups. If it fulfills its promise, it will give us a very,

very detailed roadmap to every structure, every cell type, every part of the brain. And it would be an incredibly important resource for decades. We have to take a quick break, and when we come back, more of our conversation about brain donation. Stay with us. This is Science Friday. I'm Ira Plato. In case you're just joining us, you're listening to a conversation about brain donation recorded

in front of a live Zoom audience. I'm talking with Dr. Bill Scott, executive director of the University of Miami's Brain Endowment Bank, and Tish Hevel, CEO. of the Brain Donor Project. Now I understand that you've been leading long-term research studying patients with Parkinson's. So explain to me how using a brain bank's data helps you understand about Parkinson's. So when I got started a long time ago with brain donation as part of our longitudinal study of people with Parkinson's disease.

And it was a genetic study where we wanted to understand why. certain people with particular changes in their DNA develop Parkinson's, and we wanted to see whether it led to different changes in the brain. So one of the first things that we were interested in is looking at the particular part of the brain, the substantia nigra, which is the part of the brain that goes away fastest, if you want to think of it that way, in people with Parkinson's disease. And it creates dopamine that helps you with move. and some of the signs that are well associated with Parkinson's. And we wanted to see whether there were recognizable changes.

And what we found is that there are some changes in DNA that happen after we are born. So they're called epigenetic changes that might be different in people with Parkinson's disease in these parts of the brain. And so that led us to hypothesize different ways that we might explore the bioconial. of Parkinson's disease that we weren't considering before. And so that is the kind of very detailed examination that you can get from brain tissue that you can't necessarily get from other types of samples. Let's go to Peggy. Peggy has a question about what researchers have learned about the brain through brain donations. Hi, Peggy. Welcome to Science Friday. I have something to share and something to ask. I've lived with schizophrenia most of my life. And in 2002, I joined ongoing research in

schizophrenia at the National Institute of Mental Health in Bethesda, Maryland. And several years ago, the NIMH followed up with a detailed interview. And I recently made a personal decision to donate my brain to research. And I believe research is going to end the suffering caused by mental illnesses. And this is what I'd like to know. How close is research coming to understanding the causes of mental illnesses and how to brain donation factor in? Well, I'll highlight a couple of mental health studies that I think are very important to advancing answers in this area. The NIH funds a group of studies under the Common Mind Initiative, which grew out of the genetic studies of a couple of decades ago, and it is a project that is putting together brain resources and other

data to allow us to better understand psychiatric and other neurodevelopmental conditions. Another major initiative that we haven't talked about very much here, but we're a part of here in Miami, is a brain bank at the Veterans Administration focused on post-traumatic stress disorder. And what that brain bank would really like to do is to understand in people with service-related PTSD, how their brains are affected, and we need donors with those histories to participate in that initiative as well. A short way of putting it is, if you have an interest, there is likely a brain bank that is also interested in that same thing. And it's just a matter of finding the right place for you to donate. Rebecca has a question about whether her brain

might be useful for researchers. Rebecca, hi, welcome. Hello. I was wondering, my whole life I have suffered with depression and social anxiety. That's been kind of a standard throughout my family. I became a soldier and went to Iraq, and I'm pretty positive I have blast damage for my time there, possibly CTE. So my question is, since I have two major crossover things there, would my brain still be of use? Or is it now like an outlier, you know? I don't think there's anybody who only has one thing. In fact, we sometimes say, is there really such a thing as control anymore?

We've all got stuff and we're not in silos. So, no, I think your brain would be very valuable. You've been through a lot. Thank you for asking. What about athletes and chronic traumatic encephalopathy, as you mentioned, CTE? Are you finding people donating brains? And are they becoming useful for that kind of research? So there are a couple of different places where people with CTE or suspicion that they have CTE have been donating brains.

There is a well-established CTE Brain Bank in Boston. there are CTE donors within the neurobiobank as well. There are multiple places where those donors are being registered and where they're making contributions. I think that an important point that I want to emphasize, some of these things we're talking about, we only know about after we look at the brain. So when somebody registers,

they don't necessarily register because they say I have CTE. They register because they've had concussions or they've had a TBI or they have symptoms that are consistent with it, but they don't know. And so just because you don't know for sure doesn't mean you can't register to be a donor. You describe what your exposures have been, what your history is, and the brain bank can then use that to describe the brain when people request it for research. Well, this has certainly been an enlightening discussion for me. Dr. Bill Scott, Executive Director of University of Miami's Brain Endowment Bank,

in Miami, and Tish Hevel, CEO of the Brain Donor Project based in Naples, Florida. Thank you both for taking time to be with us today. Thank you. Thank you. You can watch a full recording of the Zoom event and learn more about brain donation or pre-registered your brain. Go to ScienceFriiday.com slash brain donation. ScienceFriiday.com slash brain donation.

Scientists have long theorized that meat. Meat is what made us human. This is how the story goes. About two million years ago, Homo erectus, an early human ancestor, emerged. Homo erectus had a bigger brain, longer legs, and a smaller gut, much more human than ape. And the cause of these big evolutionary changes? Eating more meat! Yes, now a group of researchers has reanalyzed the fossil record and is starting to question the assertion

that meat eating was the primary driver of changes during this pivotal point in human evolution. Joining me now to talk more about the significance of these findings is the study's co-author Brianna Pobiner, paleoanthropologist at the renowned Smithsonian National Museum of Natural History in Washington. Welcome back to Science Friday. Thanks for having me. Glad to be here. Nice to have you. Okay, let's start off. What's the reasoning behind the meat makes us human theory? Well, the idea is that we see the evolution of the species you mentioned, Homo erectus, about to million years ago. And a little bit before that, maybe around two and a half million years ago, the archaeological record shows that stone tools are being made and animals are being

butchered, big animals, to eat meat. And so the conventional wisdom has been that since meat eating occurred a little bit before, kind of around the same time as the evolution of Homo erectus, that the physical changes and biological changes we see with the evolution of the species are closely tied to this big shift in diet. It's not that Homo erectus was the first early human to eat meat. It's that the fossil record seems to show that a spike in the amount of meat, right, in their diets. Exactly. We only see occasional meat eating, really, before Homo erectus.

And then once about two million years comes around, we all of a sudden see some archaeological sites that seem to have a lot of evidence for meat eating. So the interpretation of this increase in volume and absolute volume of butchered bone has always been, well, it's got to be a reflection of behavior of a change in diet, of more meat eating. So what did you discover that led you to believe that this theory may not be as airtight as it originally seemed? So it turns out that if you look at basically how many fossils have been dug up, the fossil record, paleontological sampling, that really increases in the same time periods that we see this big spike in evidence for meat eating. So it looks at,

It looks like it's actually just tracking sampling and that the evidence for meat eating doesn't increase substantially with the evolution of Homo erectus and stay high. There are some spikes, but it really just tracks that sampling. It seems to be really kind of a sampling signal instead of a behavioral signal. Aha. So that's really interesting. I have to ask you, though, what made you decide to look back into the fossil records? I mean, did you have an inkling that maybe there wasn't as much evidence as you thought there might be to suggest that eating more meat, you know, drove major human evolution?

So the first author of the study, Andrew Barr, contacted me and said he was assembling a group of people who were interested in basically testing this conventional wisdom. And I came on as the zoe archaeologist, somebody that studies the butcher animal fossil record. I've excavated sites with butcher animal bones for a couple of decades and I was really familiar with the evidence. So I was able to bring that side of the evidence in. And some of the other co-authors looked at the paleontological sampling and kind of wove the whole story together. And what did you actually think you would find versus what you found? Well, I thought that the conventional wisdom would hold up. I thought that we would see this bigger increase than would be expected just from changes in sampling.

So I was really surprised by our findings, actually. And some anthropologists have questioned the conclusions, correct, that you drew? based on your analysis of the fossil record? And the argument is that maybe there's less evidence of really human butchering animals because it was just less common. And it's not a matter of oversampling those 2 million-year-old records.

Well, and that still could be. I mean, basically our conclusions are that, you know, currently the evidence doesn't support this big behavioral shift at 2 million years ago, a huge increase in volume of meat eating compared to prior time periods. And ironically, it actually makes the meat eating before two million years ago look pretty impressive because there isn't a big jump at two million years ago.

There's kind of the sustained level of meat eating. Okay. So if it wasn't necessarily an uptick in meat eating that caused this major change, what are some other explanations that might be plausible? So there's some alternative hypotheses or explanations. One is that there's plant foods, maybe underground storage organs like tubers, that that was, you know, a major food source that could have led to these changes. Another idea is that it's cooking and fire and being able to extract more nutrients from the same foods or eat foods we wouldn't have otherwise. And another hypothesis maybe is that it's eating insects as kind of an alternative

protein source. The problem is that there isn't really good visible archaeological evidence for any of these alternative hypotheses back in the archaeological record this far. There's a big recent fat in eating, and it's called paleo diets, where people don't eat anything other than veggies and meat, they don't have grains or processed foods or dairy products. And they claim that they're trying to get closer to what our ancient human ancestors might have eaten. And based on this study and your past research and ancient human diets, what are these diets getting wrong? There's a lot of assumptions in the modern paleo diet movement. And I should first say that None of us on this study had any kind of paleo diet agenda that we were looking to find evidence

for or against the idea of eating a lot of meat. But really, the idea of excluding food sources, I can't imagine any early humans looking at potential food sources and going, well, we're not adapted to eating that. I don't think we're going to eat that today. It's not in my diet today. Exactly. It's not on the menu. Early human diets were really about expanding actually diet, breadth and food sources. And interestingly, there are some ideas that our species, modern humans, were so successful and may have even out-competed some other species because we ate a wide variety of food. Can't be too picky. Okay, so what's the next step? What research is needed do you think to better understand the role of meat eating and human evolution? Well, it would be great to have more

fossil samples from before two million years ago, particularly if we could find archaeological sites that had loss of layers where bones were preserved. And we could see if it's not just, you know, a handful of bones from one area on the surface or one layer, are early humans in these earlier time periods going back over and over again to butcher dozens of animals. That would maybe change the story. So as usual, it's let's get out there and find some more evidence. And you'll come back and talk about it, won't you, Brianna? I'd love to. Brianna, thank you for taking time to be with us today. Thanks for having me. Dr. Brianna Pobiner, paleoanthropologist at the Smithsonian National Museum of Natural History in Washington.

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