CARTA: Childrearing in Human Evolution – Sue Carter: Oxytocin Pathways and Human Evolution

Summary

In this engaging talk, Sue Carter explores the multifaceted role of oxytocin in human evolution and behavior. Oxytocin, often dubbed the "love hormone," plays a crucial part in social bonding and behaviors that are essential for human survival and reproduction. Carter delves into how oxytocin's effects on stress, sociality, and physiological healing have been vital across evolutionary timelines. The talk also highlights oxytocin's roles in parental behaviors, its surprising presence and significance in males, and its impact on mental and physical health. Carter's research, alongside studies in animals like prairie voles, underscores oxytocin's profound influence on the evolution of social behaviors critical to human development.

Highlights

• Oxytocin aids in forming social bonds and is essential in parental and social behaviors 🤝.
• It reduces stress, enhances trust, and promotes social connectivity through its effects on the autonomic nervous system 🧠.
• Oxytocin's significance in males has been overlooked but is essential for understanding comprehensive social behaviors 🧔.
• Studies in prairie voles highlight its role in pair bonding and bi-parental care, shedding light on human social evolution 🐹.
• The effects of oxytocin vary across genders, playing different roles in stress and social responses 🎭.

Key Takeaways

• Oxytocin is pivotal in social bonding and behaviors essential for survival and reproduction 🤝.
• This "love hormone" not only influences birth and lactation but also impacts stress and healing through the autonomic nervous system 🍼.
• Oxytocin's presence and significant roles in males were underestimated but are equally crucial 💪.
• Research in prairie voles reveals the complexity of oxytocin's social bonding role in the animal kingdom 🐾.
• Social engagement and stress-response behaviors linked to oxytocin differ between sexes, showing its diverse impacts 🌈.

Overview

Sue Carter takes us on a fascinating journey to explore oxytocin, a hormone with significant roles in human behavior and evolution. Known as the "love hormone," oxytocin helps forge social bonds crucial for survival and reproductive success. Carter emphasizes its impact not only in parental care but also in broader social interactions.

Diving into the science, Carter explains how oxytocin reduces stress and enhances trust by interacting with the autonomic nervous system. This influence spans across different species, with prairie voles offering unique insights into its role in social bonding and parenting care. This research highlights oxytocin's underestimated significance in males and its critical role in evolutionary biology.

As Carter unfolds the complex narratives around oxytocin, she enlightens us about its varying effects on males and females, particularly in social behaviors and stress responses. With its profound influence in stress buffering and social engagement, oxytocin emerges as a key player in the study of human evolution and the advancement of social behavior paradigms.

Chapters

• 00:00 - 01:00: Introduction The chapter titled 'Introduction' opens with a musical theme, setting the tone for the content that follows.
• 01:00 - 03:00: Importance of Social Bonds The chapter titled 'Importance of Social Bonds' elaborates on the necessity of social interactions for survival and reproduction among living organisms. Even simple life forms like bacteria rely on connections with others to thrive.
• 03:00 - 06:00: Oxytocin and Sociality This chapter explores the significant role of the Mia nervous system in fostering social connectivity and the necessity of a supportive social environment. Renowned researcher Hofer introduces the concept of 'hidden regulators,' emphasizing that various physiological and psychological processes unfold differently depending on social contexts. The discussion centers on the consequences of social isolation, highlighting substitutions or coping mechanisms that might develop in the absence of social interactions, such as drug abuse, overeating, and mental health challenges.
• 06:00 - 10:00: Oxytocin in Research and Application The chapter discusses the crucial role of social bonds and support in both human and non-human species. It highlights the impact of social connections on mental health, mentioning issues such as depression, illness, and even death as consequences of social isolation. The discourse underlines the evolutionary and adaptive significance of social behavior, suggesting that these constructs are best understood through their contribution to survival. Researchers are actively exploring these concepts to build a scientific understanding of social behavior.
• 10:00 - 15:00: Oxytocin and Evolutionary Significance The chapter explores the role of oxytocin in the formation of social bonds and its evolutionary significance. It begins with the assertion that survival is fundamental to nature, emphasizing the importance of not being solitary due to the survival benefits of sociality, such as safety in numbers. It questions the origins of human social behavior and suggests that it emerges from mechanisms seen primarily in parent-child interactions. The narrative implies that social bonds also develop through sexual behavior, indicating a broader framework in which human sociality is both biologically and evolutionarily ingrained.
• 15:00 - 20:00: Physiological Roles of Oxytocin This chapter discusses the evolutionary and physiological roles of oxytocin, particularly focusing on the parent-child interaction as its evolutionary prototype for social support. It highlights the significance of mother-infant and father-infant interactions, especially during birth and lactation. The chapter argues that parental and child interactions are fundamental to understanding oxytocin's social functions.
• 20:00 - 21:00: Conclusion This chapter discusses the significance of parental bonding, explaining that it's not limited to mothers. It emphasizes that even animals with typically low social interactions, like AIT tanks, exhibit strong parental behaviors. The chapter humorously references the idea of a 'love child,' implying that parenting roles transcend traditional expectations.

CARTA: Childrearing in Human Evolution – Sue Carter: Oxytocin Pathways and Human Evolution Transcription

• 00:00 - 00:30 e [Music]
• 00:30 - 01:00 most living organisms even bacteria cannot survive a reproduce alone
• 01:00 - 01:30 the Mia nervous system is a special case of needing other a functionally supportive social environments necessary my and Hofer called this hidden Regulators there's stuff going on when we're around other how do we know mostly we know what happens when we take away other substitutions occur the absence of another may may be associated with abuse of drugs food mental dysfunctions even
• 01:30 - 02:00 depression illness shutdowns and even death the need for social bonds and social support of course is not limited to humans and we've tried as we've built this new science of social behavior we've come up with the problem of what do we mean and where does it come from I know I'm preaching to the choir here when I tell you that the constructs are all best understood in the context of their evolutionary importance their adaptive importance for survival and
• 02:00 - 02:30 reproduction survival is the first law of nature it's important that we are not alone sociality has survival benefits and of course there's safety and numbers where did all this sociality come from in humans how does it sort of Bubble Up well part of it is the mechanisms for relationships can be seen first in the parent child interaction social bonds form when there's sexual behavior they form when there's
• 02:30 - 03:00 adversity when there's need for other and of course they first appear most clearly in the presence of the mother infant interaction or the father infant interaction but especially associated with birth and lactation and this was the logic that led me to study the system that we're going to talk about the evolutionary prototype I would argue for social support then is the parent child interaction and Mion sociality you can see this with your
• 03:00 - 03:30 eyes you don't need to be a scientist to understand how important this is yeah even asocial mammals like AIT tanks will show high levels of social interactions with their own offspring so we've I want I don't want to belabor this point but where we're going from this is to say that parenting is not limited to the mother unless perhaps this is Mr Obama's love child and we pretty pretty pretty sure it's
• 03:30 - 04:00 not um so going after the biology of this has led me personally at least to talk about and think about this really exciting neuropeptide known as oxytocin it plays a role in sex birth parental Behavior lactation and we don't know what it is so I'm going to ask over and over what can we how can we understand it what's oxytocin it's Central to the biology of
• 04:00 - 04:30 social behavior now we know there's social bonds social support and sexual behavior as well as other more obvious things like birth and lactation oxytocin administered in an internasal spray has become sort of the thing to do in science these days there are literally hundreds of these studies starting in Europe and now spreading all over the world they show very exciting I think important findings such as reductions in the so- called stress axis the HPA axis
• 04:30 - 05:00 uh increases in measures of trust increased attention to social stimuli increase social connectiveness brain activity and regions associated with social behavior decreases in fear oxytocin seems to help make you socially bold then we're back to this sort of evolutionary question how did we get this one hormone with so many functions historically of course breastfeeding is a method for communicating between a
• 05:00 - 05:30 baby and the mother but in this iconic picture I think this was I believe only the fifth I'm not sure uh his mistress but she did she wanted herself painted nude she often had this done and in the background is the wet nurse because there was no other way to feed that baby until very modern times really the last century so we have an extremely interesting model an oxytocin model
• 05:30 - 06:00 that we can build upon lactation and that's where I really started my own research on this studying lactating women lactation I believe allows the mother to M to manage stress more effectively she's less reactive or more appropriately reactive to stressors including the stressful stimula that come along with child rearing and also oxytocin and the events of birth and lactation make a physiological shift sort of a buffer between pregn prancy
• 06:00 - 06:30 and the postpartum period And I think that a lot of this is oxytocin based so what happens breastfeeding reduces reactivity to stressors we showed this many years ago with a collaborator Marty altimus especially in this in the face of a stressor in this case it was exercise we found enhanced immune responses in lactating women the breastfeeding women white blood cell proliferation in response to amidogen in blood taken outside the body so the
• 06:30 - 07:00 blood itself already had the capacity to be different in a breastfeeding woman so this is the magic molecule oxytocin it was one of the molecules of the decade or something recently someone made a list and put it at the top and I think it's more important than we've ever ever begun to understand it's a very simple molecule it has a ring and a tail again it was thought to be a female fale reproductive hormone and I don't
• 07:00 - 07:30 think that helped the research I think that this actually relegated oxytocin to sort of not that important until people realized men have it and they have a lot of it and it really matters and then it took off okay but we thought it was something to do with uteruses and breasts and that just was not that interesting okay however it's been known for a long time that oxytocin was made primarily in the nervous system in the brain in very
• 07:30 - 08:00 large cells known as magnos cellular neurons and as we This research has grown and I wish I had time to tell you the full story we now know that oxytocin affects social behavior and especially probably through the autonomic nervous system it's also a part of the immune system oxytocin is an Adaptive molecule it protects and heals the body in the face of challenge so it has this very interesting set of properties and I'll
• 08:00 - 08:30 argue here today that it also is one of the components that allowed us to be here today that it was necessary for the evolution of the human nervous system this is this should have been a turtle not a crocodile but I borrowed this from the internet so you get the idea it's a reptile and the our ancestor which was back here of course we are not descendant from crocodiles or or any modern reptiles but oxytocin starts to play up very important role as we get
• 08:30 - 09:00 into the primate sort of line that led to primates what it's doing I would suggest you is it allowed the transition from reptile to mammal it permits the birth helps to it doesn't cause birth but it permits it helps to expel the big brained baby from the uterus it permits postbirth nutrition supports the baby helps with lactation maternal behavior and even alop parenting as was discussed in other words others including even
• 09:00 - 09:30 fathers may be able to release or be triggered to release oxytocin in the face of the baby it facilitates the oxygenation of the brain by being part of the melinated vegus that then allows this big cortex to exist and therefore I would suggest to you that it permits human cognition and social behavior to exist of course you've seen a better better versions of this we have all kinds of special problems big sort of bony brains skulls we try
• 09:30 - 10:00 walking upright our our pelvis is designed for that and it's not very good at giving birth there are there's evidence in mice that you don't even have to have oxytocin to give birth but I think humans with all of these problems may be more dependent than rodents so we've got to get that large Ted baby outside we've got to take care of it there's actually a role for oxytocin in pregnancy infant nutrition maternal Behavior paternal Behavior alip
• 10:00 - 10:30 parental Behavior and the extended nurture that's necessary for an immature human to have the time it needs again we've learned today to grow up it doesn't work alone it has a partner Arginine Vasa pressen these evolv these two molecules evolved before at the ancestral point they were present even before the split from vertebrate to invertebrates
• 10:30 - 11:00 uh but our reptilian ancestor which I've said I I believe supposed to have been a turtle uh for mammals has the Capa did not probably have the capacity for social engagement this came along as we became mammals and that's social bonding and social engagement depended upon adaptations that seem to be related to both oxytocin and vasopress we won't have time to go through all the characteristics of these but ox to's
• 11:00 - 11:30 basic profile or Motif is pro-sociality sharing relaxation and allowing recovery or immobility without fear passive behaviors rather than active behaviors possibly chronically it's playing an extremely Ro important role in healing and it's part of the parasympathetic nervous system which then shunts oxygen to the cortex vasopress in a very similar molecule but with a very
• 11:30 - 12:00 different set of properties is associated with territoriality vigilance mobilization more active solutions to problems acutely it's very protective and it's part of the sympathetic nervous system now the sympathetic parasympathetic break is not as simple as I'm making it but working together what we had is a kind of dance between oxytocin and vasopressin with oxytocin facilitating social engagement vasopressin more associated with defense
• 12:00 - 12:30 of self and other and other might be a baby it might be a mate and so forth so this is not quite as simple as we would like and people of course are making whole professions out of studying now oxytocin and empathy oxytocin compassion oxytocin and um mindfulness you name it phas of present a little less popular but associated with extremely important things like vigilance territoriality arousal perhaps overarousal anxiety a
• 12:30 - 13:00 number of disorders may have a phasa pressent story of course we got that big brain but we didn't give up a lot of the underlying core and the problem we have as humans is we would like to tell our nervous system what to do but so much of the information is coming from all parts of the brain and it's coming up there's not that much Downstream information proportionally going through the system so the old parts of the nervous system
• 13:00 - 13:30 are still there and can influence the modern nervous system it is very hard to just say no to certain kinds of things that go on that are part of these adaptive old systems so we really need to understand them it's this is the reason though that cognition is very difficult to use to control emotion so what's oxytocin well it's a metaphor for safety it works through the autonomic nervous system in part it can be regulated by social stimulate and experience and these effects do differ
• 13:30 - 14:00 the actual amount of the hormone may not differ very often between males and females but the functions seem to and the capacity for these experiences and the use of oxytocin we've now seeing is epigenetically regulated so experience in early life especially can alter how that system is working one of the most to me exciting things that's being that's coming out of the literature is that oxytocin which is made primarily in the brain
• 14:00 - 14:30 released into into the brain and into the spinal cord but also into the blood seems to be playing a major role in healing and the capacity of the body to heal itself and this is just a laundry list of things that have recently been shown injured skin burns heart heart disease possibly bones intestines brain stroke mental disorders now oxytocin may have some General properties like
• 14:30 - 15:00 anti-inflammatory and antioxidant properties that help to explain these effects physiologically it's easiest to study these sorts of things in small rodents uh socially monogamous species are particularly helpful I've been working for the last 30 odd years with Prairie bows this species can be studied in nature and in the laboratory and they do form long- lasting pair bonds we found this in field studies in the 198 80s those studies led to kind of a
• 15:00 - 15:30 cottage industry of of uh Prairie Bowl work which I'm really excited about and I I thank all the people who have been working on these now it's it's quite exciting the first thing we saw was that when animals were mating they formed parir bonds more quickly and that was for me the first cue that was how my brain processed oxytocin must be involved because it had already been shown that oxytocin was released by sex now the Prairie has some amazing
• 15:30 - 16:00 qualities in addition to the ability to form pair bonds and be highly social they have biparental care the father helps take care of the baby there's alloparenting they do indeed have about four times more oxytocin according at least using enzyme imuno assays and they have a humanlike autonomic nervous system they have a parasympathetic sort of active active parasympathetic component this may help to explain why they're so social and why social bonds are so important in them for emotion
• 16:00 - 16:30 regulation oxytocin can probably be released that evidence isn't as good as it should be yet by sexual behavior social engagement in general maternal Behavior paternal behavior that we've shown very clearly or alloparental behavior oxytocin can also be released and this complicates my story a little bit it can be released by stressful events in fact that's the easiest way to get an elevation of oxytocin things like
• 16:30 - 17:00 social challenge forced restraint or immobility immune challenges and also chronic social isolation but only in females oxytocin is part of a component of an Adaptive coping strategy in my mind it buffers against stressors and these effects differ in males and females so I try over and over I'm always trying to kind of simplify this down to its Essence um I think it's a physiological metaphor for safety I
• 17:00 - 17:30 think it works through effects on the autonomic nervous system which then affects everything there's just nothing that the autonomic nervous system doesn't affect oxytocin has actions on the melinated vagal Pathways the parasympathetic Pathways which allow social engagement the kind of behavior that Kim saw the Prairie vs show these behaviors and I'm not going to go through all the details except to say that oxytocin is probably mainly is this
• 17:30 - 18:00 familiar you too can get this and show it in your talk what's oxytocin well I think I I filled in the blanks that uh Katie very nicely left for us I think that it's the tip of a physiological Iceberg of interactive systems with effects throughout the body it's only now being recognized I think it is a physiological metaphor for safety I think it permits encourages social behaviors and health
• 18:00 - 18:30 and of course has consequences for survival reproduction and I would argue the evolution of modern humans thank you [Music]