The conversation, in brief.
In this episode of the podcast, hosts Dave Pietraszewski and David Pinsof are joined by guest Amy Boddy from UC Santa Barbara to discuss microchimerism, evolutionary medicine, and cancer biology. The conversation explores maternal-offspring conflict during pregnancy, genomic imprinting, and how cells transferred between mother and baby can persist for decades. The speakers examine how cancer represents a breakdown of multicellular cooperation, comparing human vulnerabilities to diverse evolutionary strategies across species, such as the multiple P53 tumor suppressor genes found in elephants. Finally, they discuss academic silos, funding challenges for evolutionary biology, and the importance of integrating comparative approaches into modern medicine.
Through the conversation.
20 sections010:00 – 4:23Introduction to Microchimerism and Evolutionary Biology
Hosts Dave Pietraszewski and David Pinsof introduce guest Amy Boddy from UC Santa Barbara. They discuss the fascinating biological concepts of microchimerism, cancer biology across species, maternal-offspring dynamics, and how individuals are not entirely uniform entities.
And I did not really know what microchimerism chimerism was before going into this.
“I did not really know what microchimerism chimerism was before going into this” 0:30
Amy Boddy explains how cells cross between mother and baby during pregnancy, known as microchimerism. The hosts and guest explore the placenta as a fetal organ and the evolutionary conflict between maternal and paternal genes over resource allocation.
And across species, across mammals, this integration of the tissues is super diverse.
“across species, across mammals, this integration of the tissues is super diverse” 5:11
Humans have one of the most invasive placentas.
“Humans have one of the most invasive placentas” 6:50
0312:02 – 16:59Evolutionary Conflict and Genomic Imprinting in Pregnancy
Host Dave Pietraszewski and guest Amy Boddy discuss the evolutionary conflicts between maternal and paternal genes during pregnancy. They explore genomic imprinting, placental mammals, and the trade-offs of maternal investment, noting that paternal genes tend to extract more resources while maternal bodies face higher survival costs.
genomic imprinting um that arose with the evolution of the placenta
“genomic imprinting um that arose with the evolution of the placenta” 13:18
only placental mammals have imprinting, where the again there's like this allelic expression
“only placental mammals have imprinting, where the again there's like this allelic expression” 13:26
Amy Boddy explains how fetal and maternal cells transfer across the placenta during pregnancy and persist for decades. The speakers discuss microchimerism, where foreign cells or genetic material remain within an individual, potentially serving adaptive functions or representing historical family transmissions such as cells from older siblings.
fetal cells that get transferred into the mother's body, and there's maternal cells that get transferred into the baby's body
“fetal cells that get transferred into the mother's body, and there's maternal cells that get transferred into the baby's body” 17:10
microchimerism is a small amount, small micro of chimeric that's different, different genome within you
“microchimerism is a small amount, small micro of chimeric that's different, different genome within you” 23:00
0524:02 – 26:15Immune Tolerance of Microchimerism and Autoimmune Disease
Host David Pinsof and guest Amy Boddy discuss why the immune system tolerates fetal microchimerism cells from pregnancy, despite similarities to organ transplant rejection. They explore whether paternal genes in these cells trigger autoimmune diseases in women, noting that while autoimmune conditions are complex, specific maternal-paternal genetic matches can indeed provoke such immune reactions.
women, excuse me, are at a higher risk of developing autoimmune diseases. And some of the idea is that it could be these paternal genes expressed through these baby cells that are triggering an immune response.
“women, excuse me, are at a higher risk of developing autoimmune diseases” 24:27
you have to be predisposed to the autoimmune disease, right? And then you have to be exposed to a certain paternal allele.
“you have to be predisposed to the autoimmune disease, right? And then you have to be exposed to a certain paternal allele.” 25:41
0626:16 – 36:03The Evolutionary Puzzle of Cancer and Multicellularity
The speakers transition to discussing the evolution of cancer, contrasting external pathogens like bacteria with internal cancer cells that violate multicellular cooperation. Amy Boddy explains that cancer arises when somatic cells lose cooperative behaviors and revert to selfish proliferation, influenced by aging, tissue fitness, immune system dynamics, and trade-offs linked to placental gestation.
cells had to suppress their own interest to become a multicellular body, right? We used to be single-celled organisms that could just multiply.
“cells had to suppress their own interest to become a multicellular body, right?” 27:20
we see these genes that are important for cancer are sometimes important for implantation and fertilization.
“we see these genes that are important for cancer are sometimes important for implantation and fertilization.” 29:23
0736:03 – 44:26Potential Benefits and Evolutionary Significance of Fetal Microchimerism
Host Dave Pietraszewski and guest Amy Boddy discuss the potential physiological effects of microchimerism, examining whether persistent fetal or maternal cells provide health benefits such as tissue repair or increased longevity, and how technological advances have changed scientific perspectives on cell transfer across generations.
they found women decades later that tested positive for male origin microchimerism lived longer
“women decades later that tested positive for male origin microchimerism lived longer” 40:50
it wasn't until like the early 90s, I believe, was the first paper that showed, oh no, these cells stay around
“it wasn't until like the early 90s, I believe, was the first paper that showed, oh no, these cells stay around.” 42:06
0844:28 – 48:04Placental Invasion Types and Transmissible Cancers in Mammals
David Pinsof, Dave Pietraszewski, and Amy Boddy discuss comparative biology across mammals and marsupials, exploring theories about placental invasiveness, cancer rates, and unusual phenomena such as transmissible cancers found in Tasmanian devils and bivalves.
It's like a really nice theory. It's in evolutionary medicine textbooks. It's much messier than that
“It's like a really nice theory. It's in evolutionary medicine textbooks. It's much messier than that.” 46:00
Host Dave Pietraszewski and guest Amy Boddy discuss contagious cancers like Tasmanian devil facial tumor disease, examining how genetic bottlenecks and reduced immune recognition allow these cells to persist in other hosts, while introducing evolutionary medicine and why humans are vulnerable to diseases.
Seems like the Tasmanian devils went through a genetic bottleneck and they have reduction of their MHC receptors
“went through a genetic bottleneck and they have reduction of their MHC receptors” 50:25
And then evolutionary medicine takes a step back and says, well, why are we vulnerable in the first place?
“evolutionary medicine takes a step back and says, well, why are we vulnerable” 52:45
Amy Boddy and the hosts explore how ecological principles and evolutionary theory can improve cancer and antibiotic treatments, comparing drug resistance management to managing ecosystems and discussing how shifting treatment metaphors from total conquest to disease control changes medical practice.
Same thing with cancer cells, actually. That that mass that's in your body can start evolving
“Same thing with cancer cells, actually. That that mass that's in your body can start evolving” 54:06
Dave Pietraszewski, David Pinsof, and guest Amy Boddy discuss the challenges of integrating evolutionary medicine into traditional medical training and practice. They explore how funding agencies like the NIH often sideline basic evolutionary biology as too risky, whereas natural selection has provided robust roadmaps for addressing human diseases like cancer through comparative biology.
evolutionary medicine falls into this, like really in-between that ends up being left behind
“evolutionary medicine falls into this, like really in-between that ends up being left behind” 1:05:59
natural selection is just an incredible, much much better than any pharmaceutical company
“natural selection is just an incredible, much much better than any pharmaceutical company” 1:07:05
The hosts and guest discuss the slow uptake of evolutionary perspectives in the social sciences, psychiatry, and general education within the United States compared to countries like the UK. They examine how cultural divides, educational gaps, and the occasional misuse of evolutionary concepts hinder mainstream scientific acceptance.
there is just such a a divide in the US about even talking about evolution
“there is just such a a divide in the US about even talking about evolution” 1:10:27
You have these these misguided efforts that use evolution
“You have these these misguided efforts that use evolution” 1:12:01
Hosts Dave Pietraszewski and David Pinsof discuss how evolutionary science faces unique scrutiny and misinformation compared to other scientific fields. Guest Amy Boddy then shares her academic journey from community college and medical school interests to evolutionary biology and anthropology, reflecting on interdisciplinary silos and her current work as a biological anthropologist.
when a few crackpots and the evolutionary sciences have some stupid ideas, then it it somehow tarnishes the entire evolutionary perspective
“when a few crackpots and the evolutionary sciences have some stupid ideas, then it it somehow tarnishes the entire evolutionary perspective” 1:12:25
when you say you're a biological anthropologist, they think you're less of both somehow
“when you say you're a biological anthropologist, they think you're less of both somehow” 1:19:52
Amy Boddy explains the concept of evolutionary mismatch by comparing cancer and pregnancy patterns in humans versus chimpanzees, noting consequences of modern practices like C-sections. The speakers highlight how an evolutionary perspective emphasizes trade-offs, such as balancing the health benefits of breastfeeding for infants against the physiological costs to mothers, before introducing Peto's paradox.
mismatch is very much a part of what we're studying
“mismatch is very much a part of what we're studying.” 1:21:41
Host Dave Pietraszewski and guest Amy Boddy discuss cancer evolution, focusing on Peto's Paradox—the observation that large, multi-cellular animals like elephants have much lower cancer rates than expected given their high cell counts. Boddy explains how evolutionary theory led researchers to discover that elephants possess multiple copies of the tumor suppressor gene P53.
Richard Pito observed that larger species with more cells do not necessarily drop dead of cancer at higher rates.
“Richard Pito observed that elephants have a hundred more cells in humans.” 1:25:05
Elephants evolved multiple copies of the P53 gene, which may protect them against cancer.
“It seems like elephants have um 40 copies, potentially, up to that many.” 1:27:37
The speakers explore alternative cancer defenses across diverse species, such as whales and the remarkably long-lived Greenland shark, linking longevity to life history strategies. Finally, Boddy recommends academic resources and university centers for students interested in the interdisciplinary field of evolutionary medicine.
Different species have evolved distinct cellular mechanisms to suppress cancer across vast biodiversity.
“So elephants have the P53 solution. Whales don't. What's their solution?” 1:30:52
Extremely slow-growing species with minimal predation pressures may develop additional cellular defenses as part of their life history strategy.
“we think these very slow species are like building their cells really carefully.” 1:32:49
Host Dave Pietraszewski, David Pinsof, and guest Amy Boddy discuss recommended books in evolutionary medicine, the historical separation between evolutionary medicine and psychology, intuitive psychology or "folk medicine," and how modern scientific and medical practices share similarities with ritualistic behaviors.
And like within the evolutionary medicine field, there clearly are evolutionary psychiatrists
“evolutionary psychiatrists because that's who Randy Nessie is.” 1:37:57
And you know, it's still there's still some debate about like how much of that is actually effective
“effective and how much of it is is just kind of a a a ritual or superstition.” 1:41:26
The speakers discuss the opacity of the world, academic silos and departmental barriers in universities, and Amy Boddy shares how a transformative community college biology course and an inspiring professor led her into the field of evolutionary biology.
As as Rob Boyd once said, uh, and it always stuck with me, the world is opaque, right?
“As as Rob Boyd once said, uh, and it always stuck with me, the world is opaque” 1:43:09
It was not until a community college class that I took and it was a biology class, and the professor was amazing
“community college class that I took and it was a biology class, and the professor was amazing.” 1:46:23
Dave Pietraszewski, David Pinsof, and guest Amy Boddy discuss the challenges of securing research funding for high-risk evolutionary medicine and comparative biology projects. The hosts express appreciation for Boddy's cancer research and highlight the value of bridging evolutionary psychology with physiological and biological studies.
The hosts and Amy Boddy discuss how funding agencies often define risky research too narrowly, making unconventional scientific approaches difficult to support.
“It's like their idea of risky and my idea of risky are not in the same category.” 1:50:19
Amy Boddy notes that comparative biology remains largely understudied because research focuses primarily on a narrow set of species.
“the whole world of comparative biology is just understudied in so many different ways.” 1:51:15
The hosts conclude the episode by thanking Amy Boddy, reminding listeners to subscribe, support the podcast on Patreon, and send in guest suggestions and topic ideas. The conversation ends with lighthearted banter about merchandise requests, specifically regarding a striped fanny pack filled with french fries.
A passage from this discussion.
“If you're bringing up the phone, the french fries inside the fanny pack.” 1:53:36